CA2255963A1

CA2255963A1 - Lighting device for signalling on and identification and marking of airport traffic areas

Info

Publication number: CA2255963A1
Application number: CA002255963A
Authority: CA
Inventors: Michel Vanderen; Jean-Claude Vandevoorde
Original assignee: Individual
Current assignee: Siemens AG
Priority date: 1996-05-23
Filing date: 1997-05-23
Publication date: 1997-11-27
Also published as: EP0898682A1; CA2255964C; DE29712281U1; DE59710923D1; ATE253199T1; EP0898683A1; BR9709028A; CA2255974A1; EP0898682B1; EP0898681A1; NO985434D0; PT898681E; EP0898681B1; JP2000511333A; EP0898683B1; EP0898684B1; DK0898684T3; ATE235023T1; CA2255976A1; WO1997044613A1

Abstract

The invention relates to a lighting device for signalling on and identification and marking of airport traffic areas, e.g. take-off runways, landing runways, taxiways and the like. Said device has light sources (1) for direct emission of visible light. To reduce energy consumption and maintenance costs for said lighting devices, it is proposed that the light sources take the form of semiconductor components.

Description

CA 022~963 1998-11-20 Fl~
Description iL l~ , Lighting device for signalling on as well as designating and marking traffic areas in airports The invention relates to a lighting device for signalling on as well as designating and marking traffic areas in airports, for example runways, taxiways and the like, by means of light sources for the direct emission of visible light.
Such lighting devices, which serve as components of airport lighting systems, generally have tungsten-arc lamps or incandescent lamps as light sources. Such light sources usually have a lifetime of approximately 1000 to 1500 hours. Since lighting devices used for airport lighting systems must emit light in different colours, there is a comparatively high consumption of electrical power in the case of the operation of known lighting devices equipped with tungsten-arc lamps and incandescent lamps, since such light sources emit light in a wide range of light waves, of which only a small proportion can be used to generate light of a specific colour.
The object of the invention is to provide a lighting device of the type mentioned at the beginning which, on the one hand, permits a longer service life and, on the other hand, by means of which the outlay on power for operating the airport lighting system can be substantially reduced.
This object is achieved according to the inven-tion by virtue of the fact that the light sources of the lighting device are designed as semiconductor elements.
It is possible by means of such semiconductor elements for light to be emitted in a prescribed colour, CA 022~963 1998-11-20 without there being a need for any sort of optical radiation filtering. Even in the case of controlling such a semiconductor element, the range of wavelengths within which the semiconductor element emits light is very narrow and constant. Accordingly, such a semiconductor element scarcely generates radiation outside the visible range, in particular scarcely generates heat producing infrared radiation or ultraviolet radiation. The outlay on power for operating such a semiconductor element or a lighting device having such semiconductor elements is thus substantially reduced by comparison with conventional lighting devices, and this is to be ascribed, inter alia, to the fact that there is no need to use any sort of colour filter. Moreover, such semiconductor elements can be controlled within microseconds, by comparison with a range of seconds in the case of conventional incandescent lamps or tungsten-arc lamps; as a result, there are substantial practical advantages in traffic control in the field of airports.
The service life of such semiconductor elements is an average of approximately 70,000 hours, compared with 1000 to 1500 hours for the incandescent lamps and tungsten-arc lamps used in the lighting devices which are presently customary. Lighting devices of such a configuration render it possible for the first time for the driving of an aircraft in the area of a runway or a taxiway to be followed in real time. Using the lighting devices configured in accordance with the invention, it is possible given the appropriate selection of the semiconductor elements assembled for the lighting device to meet at once the standards in accordance with ICAO, FAA, DOT, CIE, MIL-C-25050. A further advantage of the lighting device according to the invention consists in that it already provides the luminance required to detect signals at a comparatively great distance from the lighting device, it being the case, moreover, that the risk of a dazzle effect is avoided in the case when an aircraft driver or vehicle CA 022~963 1998-11-20 driver is located at only a short distance from the lighting device.
The semiconductor elements of the lighting device according to the invention can advantageously be designed as light-emitting diodes (LEDs) or as light-emitting polymers.
It is possible for a plurality of semiconductor elements of the lighting device to form a cluster, it being possible for 2 to 200, preferably 2 to 30, semi-conductor elements to belong to a cluster. The failure ofsemiconductor elements can be compensated thereby, since a cluster having a plurality of semiconductor elements remains operable even when one or more semiconductor elements fail.
In an advantageous embodiment, the lighting device according to the invention can be designed as a cluster arrangement of a plurality of individual clus-ters, for example, of 1 to 30, preferably 1 to 16. The spatial light distribution of the lighting device can thereby be optimized in accordance with the abovemen-tioned standard requirements or other requirements. The global photometric properties of the lighting device are determined by the cluster arrangement.
In an advantageous embodiment of the lighting device according to the invention, the semiconductor elements of a cluster, which are preferably designed without a mounting, are arranged on a common substrate.
When the substrate holding the semiconductor elements is provided on its side facing the semiconductor elements with a layer made from a reflecting material, it is ensured that the radiation components of the semicon-ductor elements which are not directed towards the radiation-emitting surface of the CA 022~963 1998-11-20 cluster or of the lighting device are deflected there as far as possible.
In accordance with one embodiment of the lighting device according to the invention, in which there is arranged on the output side of the semiconductor elements a mirror surface by means of which the direction of emission of the semiconductor elements is deflected, the direction of emission of the lighting device can be provided virtually as desired, depending on the posi-tioning of the mirror surface.
When the dimensions of the radiation-emitting surface of the lighting device correspond approximately to the area of the substrate holding the semiconductor elements, the result is an emission of light from the lighting device which is uniform and thus perceived as pleasant.
When the lighting device according to the inven-tion can be assembled in a modular fashion from possibly different clusters and/or cluster arrangements, it is possible to fit such a lighting device together without great outlay for virtually any conceivable use and any conceivable requirements.
Thus, for example, a lighting device, which is of bidirectional design and has two cluster arrangements of which each emits in a direction opposite to that of the other, can be used to indicate the centre line of a straight taxiway, and also as a stop light; if the lighting device has two cluster arrangements which emit light in directions inclined to one another, they can be used on curved sections of taxiways to indicate the centre line thereof, or as a stop light.
When the cluster arrangements of this lighting device have a plurality of, for example three or five, clusters arranged next to one another, mutually juxta-posed clusters respectively enclosing an angle CA 022~963 1998-11-20 GR 97 P 3337 - 5 ~
of less than 180 degrees, it is possible to optimize the spatial distribution of the light emitted from the lighting device.
If the lighting device is intended to be of omnidirectional design, it is advantageous when its cluster arrangements are of curved design and form a circle or the lateral surface of a cylinder.
If the lighting device is to emit light in two directions, it is advantageous when the semiconductor elements are arranged in rows or in columns. If the lighting device is to emit light omnidirectionally, an arrangement of the semiconductor elements in circles or cylinders is advantageous. However, other arrangements of the semiconductor elements are also possible.
Owing to the reflecting configuration of the side of the substrate facing the semiconductor elements, it is possible to provide an elementary optical system in cooperation with the radiation-emitting sections of the semiconductor elements themselves, if the emitting sections of the semiconductor elements have the form of an aspherical lens. The use and the distribution of the generated light can hereby be of optimum configuration.
The semiconductor elements of the lighting device according to the invention can be constructed from an inorganic or organic material, in particular from plas-tic. This yields substantial advantages with regard to weight and to the possibilities of production.
Moreover, the individual clusters can be cast or injected from a plastic, it being possible to use a recyclable plastic as plastic. It is CA 022~963 1998-11-20 possible to select a material which is a good conductor of heat for the individual clusters, it also being possible to use a pressure-resistant plastic.
If the clusters form a compact unit with a housing of the lighting device, this dispenses with any sort of hollow convection space such as was necessary with the conventional tungsten-arc lamps and incandescent lamps, and also with the attendant use of metallic housings. As a result, the loads which are caused by an aircraft or another vehicle can be more effectively passed on to the roadway.
When there is arranged in front of the semicon-ductor elements of the lighting device according to the invention a cover plate by means of which the beams emitted from the semiconductor elements can be influenced optically, it is possible to improve the emission of light from the lighting device, for example by focusing and aligning the beams.
The semiconductor elements can be assigned an optical device for beam refraction and/or total reflec-tion, it being possible to provide a high-performance optical system by means of which the light emission can be optimally formed so that it satisfies in any case the requirements, already mentioned at the beginning, occur-ring in airport operation.
If the outside of the cover plate is easy toclean and is hardened, the outlay on maintenance for the lighting device can be reduced. The outside of the cover plate should expediently be of self-cleaning design, it being possible for the cover plate to be coated in a suitable way.

CA 022~963 1998-11-20 A compact configuration of the lighting device can be achieved when the semiconductor elements are arranged embedded in a filler member.
If the filler member embedding the semiconductor elements has a cutout on the active surface or the light-emitting opening of the semiconductor elements, it is possible to maintain the use of the previously explained elementary optical system, to which the reflecting configuration of the side of the substrate facing the semiconductor elements and the aspherical lens on the emitting section of the semiconductor elements belong.
In accordance with an advantageous embodiment of the lighting device according to the invention, the filler member is constructed from a transparent material, for example a transparent resin, in particular epoxy resin, whose refractive index preferably corresponds to that of the cover plate. Optical losses on the transition surface between the filler body and the cover plate are hereby eliminated.
The individual semiconductor elements are expedi-ently constructed such that they can be manipulated in a fully or partly automatic fashion.
The clusters of the lighting device according to the invention are expediently components of a redundantly operating system, with the result that it is possible in any case reliably to prevent a total failure of the lighting device according to the invention. Since, because of the redundant configuration of the system formed by the clusters, not every failure of an in-dividual semiconductor element need necessarily lead to the exchange of a cluster, the outlay on maintaining the lighting device according to the invention can be further reduced.

CA 022~963 1998-11-20 , In order further to simplify the assembly, the modification or the repair of the lighting device accor-ding to the invention, it is advantageous when one or more clusters of the lighting device is or are designed as an exchangeable subunit, in particular as a cassette.
It is then possible for a cassette belonging to the lighting device to be exchanged in situ.
Such a cassette is advantageously type coded, so that it can be installed in the lighting device exclusively in accordance with its arrangement prescribed in the lighting device; as a result, it is virtually impossible to make errors when replacing such cassettes in situ.
In an advantageous embodiment, it is possible for the purpose of realizing this type coding for there to be constructed on the outside of the cassette projections or depressions which are assigned to depressions or pro-jections, respectively, on the holder of the lighting device which holds the cassette. In the case of the cassette and in the case of the holder on the side of the lighting device, such projections or depressions can contribute to their reinforcement and capacity to resist shear stresses. Loads and stresses introduced onto the cassette can be transferred by means of the holder onto the roadway, it being possible for these to be both mechanical, specifically static and dynamic loads, and thermal loads resulting from the requirement for thermal dissipation. For the purpose of connecting the cassette, a mounting for electrical contacts which is sealed off against the environment is provided on the holder; in order to connect the cassette in the desired way to a power supply, the holder can also have a part for power supply and control.

CA 022~963 1998-11-20 When the basic body or the housing of the cas-sette is filled entirely or partly with an electrically non-conducting material, for example resin or plastic, electrical corrosion can be avoided.
If a non-conducting filler, for example glass, is added to the electrically non-conducting material, the thermal capacity for dissipation and load carrying of the cassette can be increased. The thermal resistance between the clusters present in the cassette is lowered, with the result that the transfer of heat between the clusters and the basic body or the housing of the cassette is based on thermal conduction instead of convection. Since there are no cavities inside the cassette, the cassette is inherently watertight and gastight.
If the walls, in particular a bottom wall of the basic body or of the housing of the cassette, are or is designed as thermal conductors, for example, made from stainless steel or aluminium, the temperature gradient inside the cassette can be reduced.
The outside of the cassette is advantageously provided with a hardening, at least on the main stress regions; as a result, damage owing to abrasion, scratches or point loads can be avoided to a very great extent.
Moreover, such a reinforcement, in particular at the fastening points of the cassette, can have the effect that the load stresses and shear stresses can be better distributed on the holding part of the lighting device.
Externally exposed surfaces of the cassette or of the entire lighting device can be hardened by means of sapphire or appropriate glass, so as to avoid a degra-dation of the efficiency of the lighting device owing to abrasion, or physical or chemical damage.

CA 022~963 1998-11-20 In one configuration of the lighting device as a flush-marker light, the absence of cavities ensures that the lighting device or the cassettes forming it are not exposed to bending stresses, but exclusively to compressive stresses. Since in the case of a lighting device configured in this way as a flush-marker light the rise in temperature owing to the operation of the light sources is less than 20~ of the rise in temperature in the case of conventional lighting devices, the stresses from the aircraft tyres crossing the flush-marker light can be substantially reduced. Moreover, the risk of burns can be substantially excluded for operating personnel.
In accordance with an advantageous configuration of the invention, the basic body or the housing of the lighting device is constructed from a metallic and electrically non-conducting material. The use of such materials for lighting devices in airports has not so far been practicable, since the tungsten-arc lamps and incandescent lamps used as light sources have generated excessively high temperatures. Since the non-metallic and electrically non-conducting materials which can be used in the case of the invention are electrically isolating, no electrical corrosion occurs in the case of the light-ing device according to the invention. By comparison with the materials which can be used for conventional lighting devices, the material provided in the case of the light-ing device according to the invention can be formed into virtually any shape with a low outlay. The material which can be used in the case of a lighting device according to the invention can, moreover, serve as a thermal conduc-tor, in order to dissipate the heat generated by the lighting device to the mounting part holding the lighting device, or to the roadway. Since the entire basic body or the entire housing of the lighting device according to the invention can be designed as an insulator by select-ing the material which can now be used, no costly sepa-rate insulator is required. A recyclable plastic can be used for the CA 022~963 1998-11-20 basic body or the housing of the lighting device, the outcome being the ecological advantages resulting therefrom. Since the materials which can now be used to configure the lighting device according to the invention have a substantially longer lifetime by comparison with the prior art, the use cycles of the lighting device according to the invention are correspondingly lengthened.
The semiconductor elements of the lighting device according to the invention can be controlled electrically between very low and very high potentials, the range of wavelengths of the emitted radiation being very narrow over the entire control range and entirely constant with regard to position and width, with the result that light of one and the same colour can be emitted over the entire control range.
If the lighting device according to the invention has different semiconductor elements for emitting light in different colours, it being possible for the emitted light of different semiconductor elements to be mixed arbitrarily, the light emitted from the lighting device can be set arbitrarily with regard to colour and/or intensity. It is therefore possible to use one and the same lighting device to emit light of different colour.
For this purpose, it can be advantageous for the clusters forming the lighting device to comprise semiconductor elements of different types. The efficiency of such a lighting device can be increased by virtue of the fact that the semiconductor elements emit their light with a very narrow colour bandwidth and at a very high satura-tion. Since the colour of the emitted light does not change perceptibly with control of the intensity, the colour setting can be selected with respect to the efficiency. Using a lighting device according to the invention configured in such a way, light can be emitted virtually in the entire CA 022~963 1998-11-20 visible colour range, all colours which can be used sensibly in a technical way being possible. This does not require any mechanical movement of lamps, filters or other parts to be moved physically; the corresponding properties of the lighting device according to the invention follow from static, controlled components. The addition of colours which are generated by individual semiconductor elements means that the light visible to the human eye can be of any colour, since resolution of the light of different semiconductor elements after two arc minutes corresponding to a distance of 0.5 m from the lighting device can no longer be resolved.
The lighting device expediently has a control device for controlling the power supply, by means of which the lighting device can be dimmed and/or switched.
When this control device has an electronic light controller, the sensitivity of the semiconductor elements can be adapted to the customary sensitivity of incan-descent lamps and tungsten-arc lamps, so that the light-ing device according to the invention can be combined inthe same system with conventional lighting devices having tungsten-arc lamps and incandescent lamps.
The control device can be connected for sig-nalling purposes to a central unit by a power supply line and/or a separate electric or optical data line. The control device can serve to control the intensity of emission of the semiconductor elements. Moreover, it can be prescribed by means of the control device in which of several possible directions light is emitted, if the lighting device is designed as a bidirectional or omni-directional lighting device.

CA 022~963 1998-11-20 By means of this control device the intensity of emission and the number of the semiconductor elements emitting light of different colour can be set so that the lighting device can be used to emit light of any desired colour at any desired intensity.
Moreover, the control device can set a specific succession of OFF and, if appropriate different, ON
operating states.
Of course, it is possible in accordance with an advantageous embodiment of the lighting device according to the invention to use the control device to monitor the operating state and the operability of the semiconductor elements functioning as light source.
When one or more clusters of the lighting device according to the invention has or have semiconductor elements which emit red, green or blue light and are arranged alternately, it is possible for the variable white light which is particularly important in operating an airport to be emitted in any desired form. As a result, the lighting device can be adapted in an optimum way to different climatic conditions, it naturally being possible, in addition, to take account of different lighting conditions as well. Since red, blue and green are arranged at the outer corners of a colour triangle, and the lighting device can have a desired number of corresponding semiconductor elements, this lighting device can be used to generate all the colours provided according to the standards already named at the begin-ning. Moreover, the lighting device according to the invention can be used immediately to fulfil the require-ments with regard to light propagation.

CA 022~963 1998-11-20 If the aim is to use the lighting device accor-ding to the invention to emit only red, yellow, orange and green light, it is sufficient if one or more clusters has or have semiconductor elements which emit red or green light and are arranged alternately. Semiconductor elements emitting blue light are not required in this case, since they are not important for the emission of light in the abovementioned colours. If light is to be generated only in the said four colours, specifically red, yellow, orange and green, the result of dispensing with semiconductor elements emitting blue light is that the lighting device according to the invention can be configured with smaller dimensions in conjunction with the same possible light intensity.
It is possible to arrange mutually juxtaposed rows of semiconductor elements of a cluster offset relative to one another, resulting in some circumstances in a denser population of a substrate with semiconductor elements.
If the control device of the lighting device according to the invention has a pulse-width modulation device by means of which the electrical power fed to the semiconductor elements can be controlled, the result is a high efficiency for operating the lighting device according to the invention, it being possible for the power rendered available to be adapted in an optimum way to the requirements of the lighting device or the requirements of the semiconductor elements by means of the pulse-width modulation device. There is no need for a thyristor-controlled power supply which, in its turn, would typically cause harmonization and reactive losses in the main source. Moreover, the operation of the lighting device according to the invention produces no stroboscopic effect which could impair the correct perception of the lighting device.

CA 022~963 1998-11-20 The invention is explained in more detail below with the aid of exemplary embodiments and with reference to the drawing, the application of the invention in the field of airports, in particular, being described.
Figure 1 shows a representation of the principle of a semiconductor element designed as a light-emitting diode;
Figures 2 to 4 show, in front, side and top views, the principle of a first embodiment of a cluster of a lighting device according to the invention;
Figures 5 to 7 show, in front, side and top views, the principle of a second embodiment of a cluster of the lighting device according to the invention;
Figure 8 shows a top view of a first exemplary embodiment of the lighting device according to the nvent lon;
Figure 9 shows a top view of a second exemplary embodiment of the lighting device according to the invention;
Figure 10 shows a top view of a third exemplary embodiment of the lighting device according to the invention;
Figure 11 shows a sectional representation of the exemplary embodiment, represented in Figure 8 for example, of the lighting device according to the inven-tion;
Figure 12 shows a representation corresponding to Figure 11, the lighting device being constructed from clusters in accordance with Figures 5 to 7;
Figure 13 shows a further embodiment of the lighting device according to the invention;
Figures 14 to 17 show representations of the principle of clusters having different semiconductor elements;
Figure 18 shows a representation of the fixed colours provided for airport lighting systems;
Figure 19 shows a representation of the principle of the control, regulation and monitoring of airport lighting systemsi .

CA 022~963 1998-11-20 Figure 20 shows a representation of the principle of the output side of a pulse-width modulation device of the lighting device according to the invention;
Figure 21 shows a control device of the lighting device according to the invention; and Figure 22 shows a modified control device of the lighting device according to the invention.
A lighting device according to the invention has a multiplicity of semiconductor elements which are designed in the case of the embodiments described below as light-emitting diodes 1. The light-emitting diode 1 represented in principle in Figure 1 has, in that region in which the light generated emerges from the diode 1, a configuration as an aspherical lens 2, as is represented, in particular, in Figure 1.
Owing to the aspherical configuration of the light-refracting lens 2, the distribution of the light emitted by the diode 1 can be optimized.
The light-emitting diode 1 is, in particular, a bright or superbright LED.
The lighting device according to the invention is assembled from a multiplicity of previously described light-emitting diodes 1. A plurality of such light-emitting diodes 1 can be combined to form a cluster 3 represented in Figures 2 to 4. In the exemplary embodi-ment represented in Figures 2 to 4, the cluster 3 has ten light-emitting diodes 1, which are arranged in two rows, of five light-emitting diodes 1 each, arranged one above another.

CA 022~963 1998-11-20 It is possible for the centre lines of the diodes 1 of a row to be arranged inclined with respect to the centre lines of the diodes 1 of a neighbouring row.
A11 the light-emitting diodes 1 of this cluster 3 are arranged without a mounting on a substrate 4 which serves as a holder for the light-emitting diodes 1. The cluster 3 has an elementary optical system, to which there belongs a reflecting layer 5 which is applied to the side of the substrate 4 facing the light-emitting diodes 1. The aspherical lenses 2 of the light-emitting diodes 1, which optimize the use and distribution of the light generated by the light-emitting diodes 1, belong to this elementary optical system. The aspherical lens 2 respectively forms the actual active surface or the light-emitting opening of the light-emitting diodes 1.
The cluster 3 represented in Figures 2 to 4 is configured as a module part which can be assembled with other identical or similar clusters 3. On the light-emitting surface 6, the cluster 3 is closed by means of a cover plate 7 which, in the case of the cluster 3 represented in Figures 2 to 4, is arranged parallel to the substrate 4. With regard to its dimensions, the radiation-emitting surface 6 of the cluster 3 corresponds essentially to the surface of the substrate 4, which is virtually completely covered by the light-emitting diodes .

The light-emitting diodes 1 of the cluster 3 are surrounded by a filler member 8 which fills up the space between the substrate 4 and the cover plate 7 and is produced from a transparent material, for example from a resin. The filler member 8 has a cutout 9 which is assigned directly to the emitting section of the cluster 3 formed by the aspherical lenses 2 of the light-emitting diodes 1 of the cluster 3;

. . .

CA 022~963 1998-11-20 the cutout 9 is constructed between the active surface of the light-emitting diodes 1 of the cluster 3 and the filler member 8, in order not to lose use of the elementary optical system formed by the reflecting layer 5 of the substrate 4 and the aspherical lenses 2 of the light-emitting diodes 1.
The refractive index of the material forming the filler member 8 expediently corresponds to that of the material forming the cover plate 7. As a result, optical losses at the contact surface between the filler member 8 and the cover plate 7 can be prevented.
The outside of the cover plate 7 of the cluster 3 is of hardened and smooth configuration; it can, moreover, be self-cleaning.
In the embodiment of the cluster 3, as it is represented in Figures 2 to 4, the direction of emission, represented by the arrow in Figure 3, of the cluster 3 is arranged perpendicular to the plane of the substrate 4.
In the embodiment, represented by Figures 5 to 7, of the cluster 3, the direction of emission, represented by the arrow in Figure 6, of the cluster 3 is deflected by 90 degrees, for which purpose a mirror surface 10 is provided which is arranged between the light-emitting diodes 1 and the radiation-emitting surface 6 of the cluster 3. The mirror surface 10 resets the light beams by 90 degrees in the exemplary embodiment represented, with the result that they emerge parallel to the plane of the substrate 4 from the cluster 3 through the light-emitting surface 6 thereof or through the cover plate 7 thereof.
A taxiway centre and stop light for a straight section of a taxiway is represented in Figure 8. What is involved in this case CA 022~963 1998-11-20 is a so-called bidirectional lighting device, having a first cluster arrangement 11, which emits in the direction marked by the arrow 13, and a second cluster arrangement 12, which emits in the direction opposite to that of the cluster arrangement 11 and marked by the arrow 14.
The lighting device represented in Figure 8 is a compact device, the two cluster arrangements 11, 12 being arranged in a common housing 15. That region of the interior of the housing 15 which is arranged between the two cluster arrangements 11, 12 as well as, in Figure 8, to the side of the two cluster arrangements 11, 12 is filled with a suitable material. The housing 15 can be of metal construction.
Apart from the fact that they emit in different directions, the cluster arrangements 11, 12 corresponding to one another, and so only the cluster arrangement 11 on the right in Figure 8 is described in detail below.
The cluster arrangement 11 has three clusters 3, which are arranged in a row next to one another, it being possible for each of these clusters 3 to have, for example, the embodiment represented by Figures 2 to 4.
The middle cluster 3 is arranged at right angles to the centre line 16 of the taxiway, intersecting this centre line 16 in its middle region. The two outer clusters 3 respectively enclose with the middle cluster 3 an angle which is slightly less than 180 degrees. An efficient horizontal light distribution is achieved hereby. The cover of the lighting device represented in Figure 8 has a hardened, smooth outer surface which is thereby configured such that it can be cleaned in a simple way.

. _ CA 022~963 l998-ll-20 The lighting device represented in Figure 9 likewise serves for marking the centre line of a taxiway, but on a curved section thereof, and as a stop light which can be used there. It differs from the lighting device represented in Figure 8 by virtue of the fact that the directions of emission of the two cluster arrange-ments 11, 12 are inclined to one another, and that there are provided per cluster arrangement 11, 12 five indi-vidual clusters 3, which can likewise be such as the embodiments represented in Figures 2 to 4. Since a curved section of the taxiway is involved, the middle cluster 3 of the two cluster arrangements 11, 12 is offset and inclined to the centre line CL of the lighting device.
The clusters 3 of the two cluster arrangements 11, 12 likewise enclose with the respectively adjacent cluster 3 an angle alpha which is less than 180 degrees.
Figure 10 shows a lighting device which acts in all directions and can likewise be provided for marking a taxiway. Six curved clusters 17, which form a closed circle with one another and are separated from one another by structural ribs 18, are provided in the embodiment represented. Light can be emitted virtually in all directions by means of the six curved clusters 17.
In the lighting devices described above with the aid of Figures 8 to 10, the outer optical surface can be of transparent and hard configuration, for example made from sapphire or glass with a hardened surface, so that a degradation of the efficiency of the lighting devices because of abrasion and physical or chemical damage is avoided. The outer optical surface can be hardened or coated in such a way that any possible Fresnel losses are reduced.

CA 022~963 1998-11-20 Represented in Figures 11 and 12 are cross-sections through lighting devices, which correspond, for example, to the lighting devices represented in Figures 8 to 10, and are designed as flush-marker lights. They differ from one another essentially in that, in Figure 11, the clusters 3 of the embodiment described with the aid of Figures 2 to 4 are used, whereas in the case of the flush-marker light in accordance with Figure 12 use is made of clusters of the embodiment explained with the aid of Figures 5 to 7.
The lighting device in accordance with Figures 11 and 12 is arranged with substantial parts below ground level 19. The arrows represented in Figures 11 and 12 mark the directions of emission of the flush-marker lights. As follows, in particular, from Figure 11, the part of the flush-marker light having the cluster or clusters 3 is configured in the form of a cassette 20 which, as such, forms a unit which can be exchanged without a high outlay. Such a flush-marker light can have one or more such cassettes 20. Depending on the configu-ration of the lighting device, a plurality of identical or, possibly, also different cassettes can be assembled to form the lighting device.
In an advantageous embodiment, such a cassette 20 is type coded, the type coding corresponding to its arrangement inside the lighting device. As a result of this, errors are rendered virtually impossible during an in situ replacement of the cassette 20. The type coding can be implemented by projections or cutouts on the cassette side, corresponding cutouts or projections then being provided in a holding part 21 of the lighting device. Such relief-type configurations of the cassette 20 and of the holding part 21, or configurations provided with indentations can, moreover, contribute to the capacity to withstand shear stresses.

CA 022~963 1998-11-20 The basic body or the housing of the cassette 20 is filled entirely or partially with an electrically non-conducting material, for example a resin or plastic;
electrical corrosion is avoided hereby. A thermally conducting material, for example glass, can be added to the non-conducting material, in order thus to increase the capacity of the cassette 20 for thermal dissipation and its capacity for accepting loads.
The thermal transmission between the clusters 3 and the basic body or the housing of the cassette 20 is then based on thermal conduction instead of air/gas convection, with the result that the thermal resistance of the cassette 20 is substantially reduced.
Since no convection gas is present, any possible aircraft or vehicle loads which act on the cassette 20 do not lead to bending stresses, but exclusively to compressive stresses, which can be absorbed or dissipated more easily.
The cassette 20 is inherently watertight and gastight, because there are no cavities, and thus no convection gas, inside the cassette 20.
The rise in temperature occurring in the cassette 20 is only less than 20~ of the rise in temperature in the case of a lighting device with a conventional tungsten-arc light source, with the result that aircraft or vehicle tyres are by far less stressed, and burning of operating and maintenance staff can be excluded.
The bottom wall of the cassette 20 can be con-structed by a thermal conductor, for example stainless steel or coated aluminium; the temperature gradient inside the cassette 20 is reduced hereby.

CA 022~963 1998-11-20 The outside of the cassette 20 can be constructed in a hardened fashion, for example from a stainless steel, thus avoiding damage owing to abrasion, scratches or point loads.
Fastening points of the cassette 20 can be of reinforced design, so that load and shear stresses on the structure supporting the cassette 20 or on the holding part 20 can be distributed more effectively.
The introduction of power or the transmission of signals into the cassette 20 is accomplished by self-cleaning and self-sealing contacts. Watertight and vapourtight protection against the environment is provided.
Because of the design of the lighting device with light-emitting diodes 1, the transmission of electrical power between the cassette 20 and the remaining parts of the lighting device is performed at a very low voltage level, with the result that it is possible to carry out a "hot" cassette replacement without the danger of damaging the electrical contacts and without the risk of electric shock to the staff; in this case, the voltage level is below a peak voltage of approximately 25 V.
The cassette 20 is arranged above a power supply and control device 22 of the lighting device.
Since the cassette 20 is constructed as far as possible without cavities, it resists mechanical stresses of 100 G and vibrational stresses of up to 30 G, it being unimportant whether the lighting device is energized or not energized.

CA 022~963 1998-11-20 Loads and stresses introduced onto the cassette 20 are transferred onto the roadway by means of the holding part 21. These stresses are static and dynamic mechanical loads as well as thermal loads which arise from the need to dissipate the heat produced.
Figure 13 shows an embodiment of the lighting device which is arranged in a conventional way above a roadway. There, too, a cassette 20 configured to be capable of exchange in a modular fashion is arranged above a power supply and control device 22, the power supply and control device 22 being arranged above the ground level 19 with the aid of a detachable coupling 23.
Figure 14 shows a representation of the principle of a cluster 3 which is assembled from red, yreen and blue light-emitting diodes 1. In a way still to be described, the intensity with which the light-emitting diodes 1 emit light of each colour can be controlled.
Owing to the fact that the light-emitting diodes 1 of each of the three colours can emit light at the respec-tively desired intensity, light can be emitted virtuallyin all visible colours by means of the cluster 3 shown in Figure 14, it being possible, moreover, for this light to be emitted at different intensities. As follows, in par-ticular, in conjunction with Figure 18, the colours of red, green and blue provide the possibility of emitting light of any intensity and in any colour conceivable for possible signals.
Such a configuration of a cluster 3 can also be used to emit white light at different intensities, some-thing which is difficult with conventional lightingdevices. The reason for this is that red, green and blue are arranged in the colour spectrum approximately at the corners of a triangle CA 022~963 1998-11-20 which describes the visible colour range, as follows from Figure 18.
The light emerging from the cluster 3 can no longer be differentiated into individual light sources at a distance of two arc minutes corresponding to an obser-ving distance of 10 m, with the result that light can be produced in the desired colour and intensity for all purposes. This also holds, in particular, for the stan-dards ICAO, FAA, DOT, CIE, MIL-C-25050 valid in aviation.
A cluster 3 which, as already mentioned, contains light-emitting diodes 1 whose light is red, blue or green is best suited for generating variable white light. As already mentioned, these three colours are arranged at the outer corners of a triangle which is to be seen in Figure 18 and corresponds to the said standards.
Only four colours, specifically red (R), yellow (Y), orange and green (G) are required to mark taxiway markings and route information. It is simpler and less expensive for such an application when a cluster 3 contains only two different types of light-emitting diodes 1, specifically ones which emit red light, and ones which emit green light. Such a cluster 3 is repre-sented in principle in Figure 15. Diodes 1 emitting blue light can be dispensed with in this case.
The clusters 3 in accordance with Figure 16 and Figure 17 differ from the clusters 3 represented in Figure 14 and Figure 15 only by virtue of the fact that the individual light-emitting diodes 1 are not arranged in rows offset relative to one another; in the case of the clusters 3 in accordance with Figures 16 and 17, the CA 022~963 1998-11-20 light-emitting diodes 1 arranged below or above one another are not offset relative to one another.
Light-emitting diodes 1 are available on the market from different manufacturers and in different colours. Thus, for example, the Toshiba company manufac-tures LEDs for emitting light in red, orange and yellow colours; the Hewlett-Packard company manufactures diodes for emitting light in amber, orange, red-orange and red colours; the Ledtronics company manufactures diodes for emitting light in green, yellow, orange, red and blue colours.
The supply of power to the light-emitting diodes 1 is controlled with minimum losses by a pulse-width modulation device 24, the peak current being set in an initialization method by means of which the type of the light-emitting diode is identified in accordance with the result of a comparison of the voltage drop across a chain of light-emitting diodes with the voltage drop across a reference LED.
The control or inclusion and integration of the lighting devices according to the invention into a control system of an airport will now be explained with the aid of Figure l9.
An air traffic control centre 25, an emergency control centre 26 and a maintenance control centre 27 are connected in a suitable way to a controller 28 for routes and gates. This controller 28 is connected, in turn, to substations 29, 30, 31, of which only the substation 29 is represented in detail in Figure 19.
It may be pointed out that a star-shaped connec-tion between the controller 28 and the substations 29, 30, 31 is represented in Figure 19, but that it is also possible in principle CA 022~963 1998-11-20 to provide a loop connection or a bus connection.
The substation 29 has a subcontrol device 32 with a panel 33. Via a CCR 34 and a master circuit 35 in each case, the actual control devices 22 of the lighting devices according to the invention are connected to the subcontrol device 32.
The already mentioned pulse-width modulation device 24 belongs to the control device 22, which is represented in detail in Figures 21 and 22. The output power of the said pulse-width modulation device 24 can vary, as emerges from Figure 20, whose upper part rep-resents an output power of the pulse-width modulation device 24 with a low intensity, and whose lower part rep-resents an output power of the pulse-width modulation device 24 with a high intensity.
The control devices 22 represented in Figures 21 and 22 differ from one another only in that the control device 22 represented in Figure 21 has no separate data line 36, but has only a power supply line 37, which also serves the purpose of data transmission.
The control device 22 includes a power adapting and sensor unit 38 which is connected to the pulse-width modulation device 24 and a controller 39.
The pulse-width modulation device 24 is likewise connected to the controller 39 and an outlet sensor 40, which is likewise connected to the controller 39 and via which the light-emitting diodes 1 of the lighting device are driven. The controller 39 is connected to the power supply line 37 or the data line 36 via a modem 41 and a connecting circuit 42.

CA 022~963 1998-11-20 A unit of the Intel 8051 type can be used as the controller 39. A PC can be used as the substation control device 32, a SICOMP-PC being a possibility.
The control of the lighting device includes the regulation of the intensity of emission of the diodes 1, the selection of that direction or those directions in which light is to be emitted from the lighting device, the selection of the colour in which light is to be emitted, the light flash coding or the time sequence of light pulses, ON and/or OFF operation controlled as a function of time, monitoring of the diodes 1, and auto-matic "power on default start-up" selection and an automatic "fallback default" selection in the event of control failure. Further optional features are possible.
The input power incoming at the control device 22 is automatically detected and adapted to the requirements of the lighting device.
In the case of a standard constant-current series circuit input power, the output power of the pulse-width modulation device 24 is adapted such that the exponential response typical of tungsten-arc lamps or incandescent lamps is produced, with the result that the lighting device according to the invention can be combined with conventional lighting devices in one and the same cir-cuit.
The modem 42 codes the modulated control signalsfrom the power supply line 37 or the data line 36 and assigns the control signals. The modem 41 alternately modulates and codes monitoring signals which come from the lighting device, in order to make these available to a central control and monitoring system. The modem 41 operates CA 022~963 1998-11-20 in two directions, in order to be able to transmit the control and monitoring signals in a suitable way.
A component of the control device 22 is a moni-toring part by means of which the lighting device is monitored for line interruption, earth fault, supply lead faults and the like.
The clusters 3 can, for example, also be moni-tored for operability by means of a selenium cell.

Claims

1. Flush-marker light of an airport lighting system for signalling on as well as designating and marking traffic areas in airports, for example runways, taxiways and the like, by means of light sources (1) for the direct emission of visible light, characterized in that the light sources are designed as semiconductor elements (1).

2. Flush-marker light according to Claim 1, whose semiconductor elements (1) are designed as light-emitting diodes (LEDs) or as light-emitting polymers.

3. Flush-marker light according to Claim 1 or 2, in which a plurality of semiconductor elements (1) form a cluster (3).

4. Flush-marker light according to Claim 3, in which 2 to 200, preferably 2 to 30, semiconductor elements (1) form a cluster (3).

5. Flush-marker light according to Claim 3 or 4, which is designed as a cluster arrangement of a plurality of individual clusters (3).

6. Flush-marker light according to Claim 5, in which 1 to 30, preferably 1 to 16, clusters (3) form a cluster arrangement (11, 12).

7. Flush-marker light according to one of Claims 3 to 6, in which the semiconductor elements (1) of a cluster (3) are arranged on a common substrate (4).

8. Flush-marker light according to one of Claims 1 to 7, whose individual semiconductor elements (1) are designed without a mounting.

9. Flush-marker light according to Claim 7 or 8, in which the substrate (4) holding the semiconductor elements (1) is provided on its side facing the semi-conductor elements (1) with a layer (5) made from a reflecting material.

10. Flush-marker light according to one of Claims 1 to 9, in which there is arranged on the output side of the semiconductor elements (1) a mirror surface (10) by means of which the direction of emission of the semiconductor elements (1) is deflected.

11. Flush-marker light according to one of Claims 7 to 10, the dimensions of the radiation-emitting surface (6) of which correspond approximately to the area of the substrate (4) holding the semiconductor elements (1).

12. Flush-marker light according to one of Claims 3 to 11, which can be assembled in a modular fashion from possibly different clusters (3) and/or cluster arrangements (11, 12).

13. Flush-marker light according to Claim 12, which is of bidirectional design and has two cluster arrangements (11, 12) of which each emits light in a direction opposite to that of the other.

14. Flush-marker light according to Claim 12, which is of bidirectional design and has two cluster arrangements (11, 12) which emit light in directions inclined to one another.

15. Flush-marker light according to Claim 13 or 14, in which each cluster arrangement (11, 12) has a plurality of, for example three or five, clusters (3) arranged next to one another, mutually juxtaposed clusters (3) respectively enclosing an angle of less than 180 degrees.

16. Flush-marker light according to Claim 12, which is of omnidirectional design and whose cluster arrangements are of curved design and form a circle or the lateral surface of a cylinder.

17. Flush-marker light according to one of Claims 1 to 16, whose semiconductor elements (1) are arranged in rows or columns.

18. Flush-marker light according to one of Claims 1 to 16, whose semiconductor elements (1) are arranged in circles or cylinders.

19. Flush-marker light according to one of Claims 1 to 18, whose semiconductor elements have an emitting section (2) in the form of an aspherical lens.

20. Flush-marker light according to one of Claims 1 to 19, in which the semiconductor elements (1) are constructed from an inorganic or organic material, in particular from plastic.

21. Flush-marker light according to one of Claims 3 to 20, in which the individual clusters (3) are constructed by being cast or injected from a preferably recyclable plastic.

22. Flush-marker light according to one of Claims 3 to 21, in which the individual clusters (3) are constructed from a material which is a good conductor of heat.

23. Flush-marker light according to one of Claims 3 to 22, in which the individual clusters (3) are constructed from a pressure-resistant plastic.

24. Flush-marker light according to one of Claims 3 to 23, in which the clusters (3) form a compact unit with a housing (15) of the lighting device.

25. Flush-marker light according to one of Claims 1 to 24, in which there is arranged in front of the semiconductor elements (1) a cover plate (7) by means of which the beams emitted from the semiconductor elements (1) can be influenced optically.

26. Flush-marker light according to Claim 25, in which the beams can be focused and directed by means of the cover plate (7).

27. Flush-marker light according to Claim 25 or 26, in which the semiconductor elements (1) are assigned an optical device for beam refraction and/or total reflection.

28. Flush-marker light according to one of Claims 25 to 27, in which the outside of the cover plate (7) can be easily cleaned and is hardened.

29. Flush-marker light according to Claim 28, in which the outside of the cover plate (7) is coated.

30. Flush-marker light according to one of Claims 1 to 29, whose semiconductor elements (1) are arranged embedded in a filler member (8).

31. Flush-marker light according to Claim 30, in which the filler member (8) of the semiconductor elements (1) has a cutout (9) on the active surface or light-emitting opening (2) of the semiconductor elements (1).

32. Flush-marker light according to Claim 30 or 31, whose filler member (8) is constructed from a transparent material, for example a transparent resin, in particular epoxy resin, whose refractive index preferably corresponds to that of the cover plate (7).

33. Flush-marker light according to one of Claims 1 to 32, whose individual semiconductor elements (1) are constructed such that they can be manipulated in a fully or partly automatic fashion.

34. Flush-marker light according to one of Claims 3 to 33, whose clusters (3) are components of a redundantly operating system.

35. Flush-marker light according to one of Claims 3 to 34, in which one or more clusters (3) of the lighting device is or are designed as an exchangeable subunit, in particular as a cassette (20).

36. Flush-marker light according to Claim 35, in which the cassette (20) is type coded.

37. Flush-marker light according to Claim 36, in which there are constructed on the outside of the cassette (20) projections or depressions which are assigned to depressions or projections, respectively, on the holder (21) of the lighting device which holds the cassette (20).

38. Flush-marker light according to one of Claims 35 to 37, in which the basic body or the housing of the cassette (20) is filled entirely or partially with an electrically non-conducting material, for example resin or plastic.

39. Flush-marker light according to Claim 38, in which a non-conducting filler, for example glass, is added to the electrically non-conducting material.

40. Flush-marker light according to one of Claims 35 to 39, in which the walls, in particular a bottom wall of the basic body or of the housing of the cassette (20), are or is designed as a thermal conductor, for example made from stainless steel or aluminium.

41. Flush-marker light according to one of Claims 35 to 4 O, in which the outside of the cassette ( 20) is provided with a hardening, at least on the main stress regions.

42. Flush-marker light according to one of Claims 1 to 41, whose basic body or housing is constructed from a non-metallic and electrically non-conducting material.

43. Flush-marker light according to one of Claims 1 to 42, whose semiconductor elements (1) can be controlled electrically between very low and very high potentials.

44. Flush-marker light according to one of Claims 1 to 43, which has different semiconductor elements (1) for emitting light in different colours, it being possible for the emitted light of different semiconductor elements (1) to be mixed arbitrarily.

45. Flush-marker light according to one of Claims 1 to 44, which has a control device (22) for controlling the power supply and by means of which it can be dimmed and/or switched.

46. Flush-marker light according to Claim 45, whose control device has an electronic light controller.

47. Flush-marker light according to Claim 45 or 46, whose control device (22) is connected for signalling purposes to a central unit by a power supply line (37) and/or a separate electric or optical data line (36).

48. Flush-marker light according to one of Claims 45 to 47, whose semiconductor elements (1) can be controlled with regard to their intensity of emission by means of the control device (22).

49. Flush-marker light according to one of Claims 45 to 48, by means of which light can be emitted in a plurality of directions, and by means of whose control device (22) the direction of emission or the directions of emission can be selected.

50. Flush-marker light according to one of Claims 45 to 49, by means of whose control device (22) the intensity of emission and the number of the semiconductor elements (1) emitting light of different colour can be set so that the lighting device can be used to emit light of any desired colour at any desired intensity.

51. Flush-marker light according to one of Claims 45 to 50, by means of whose control device (22) it is possible to set a specific succession of OFF and, if appropriate different, ON operating states.

52. Flush-marker light according to one of Claims 45 to 51, by means of whose control device (22) the operating state and the operability of the semiconductor elements (1) can be monitored.

53. Flush-marker light according to one of Claims 3 to 52, in which one or more clusters (3) has or have semiconductor elements which emit red, green or blue light and are arranged alternately.

54. Flush-marker light according to one of Claims 3 to 52, in which one or more clusters has or have semi-conductor elements (1) which emit red or green light and are arranged alternately.

55. Flush-marker light according to one of Claims 3 to 54, in which mutually juxtaposed rows of semiconductor elements of a cluster (3) are arranged offset relative to one another.

56. Flush-marker light according to one of Claims 45 to 55, whose control device (22) has a pulse-width modulation device (24) by means of which the electrical power fed to the semiconductor elements (1) can be controlled.