CA2255964C

CA2255964C - Lighting device for signalling, identification or marking

Info

Publication number: CA2255964C
Application number: CA002255964A
Authority: CA
Inventors: Jean-Claude Vandevoorde
Original assignee: Siemens AG
Current assignee: ADB bvba
Priority date: 1996-05-23
Filing date: 1997-05-23
Publication date: 2007-02-06
Anticipated expiration: 2017-05-23
Also published as: AU3088997A; CA2255963A1; EP0898683A1; ATE235023T1; CA2255976A1; DK0898682T3; KR20000015906A; KR20000015907A; NO320724B1; ES2150255T3; PT898683E; AU3024997A; ATE253199T1; BR9709355A; JPH11514136A; CN1103894C; PT898681E; BR9709026A; DE59702145D1; DE59709576D1

Abstract

The invention relates to a lighting device for signalling, identification or marking which has light sources in the form of semiconductor components (1), e.g. light-emitting diodes or light-emitting polymers. To adapt said lighting device to different climatic or light conditions, it is proposed to provide the lighting device with a control device (22) which can be used to vary in a controlled manner the emission intensity of the light emitted by the semiconductors.

Description

FiL~. f~"a-~*"° '~_''~ A~:?f'l~f~~.:.k Description '.~.~:;'L~ff~l~d Lighting device for signalling, designating or marking The invention relates to a lighting device for signalling, designating or marking, having light sources which are designed as semiconductor elements, for example as light-emitting diodes (LEDs) or as light-emitting polymers.
It is possible by means of such semiconductor elements for light to be emitted from a lighting device outlined above in a prescribed colour, without there being a need for any sort of optical radiation filtering.
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 low.
It is the object of the invention to make avail able, starting from the prior art outlined above, a lighting device whose light emission can be adapted in a simple way to different requirements and to different light conditions.
This object is achieved according to the inven tion owing to the fact that the lighting device has a control device by means of which the intensity of the light emission of the semiconductor elements is variable in a controlled fashion. As a result, the light emission of the lighting device can be adapted to the most dif-ferent conditions by varying the intensity with which the semiconductor elements emit light. Since, even when their light emission is controlled with regard to intensity, such semiconductor elements emit light with a range of wave-lengths which is very narrow and constant, the colour of the light emitted from the lighting device is the same for a different intensity of the emitted light. Adapting the light emission of the semiconductor elements to changes prescribed by the control device is performed in microseconds, as a result of which the lighting device according to the invention can also satisfy strict requirements.
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 col-our. 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 saturation. 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 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 compo nents. 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 dis-tance of 0.5 m from the lighting device can no longer be resolved.
The lighting device can expediently be dimmed and/or switched by means of the control device serving to control the power supply.
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 in the 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.
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 the lighting device according to the inven tion has semiconductor elements which emit red, green or blue light and are arranged alternately, it is possible in particular 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 condi-tions 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 semi-conductor elements, this lighting device can be used to generate all the colours. Moreover, the lighting device according to the invention can be used immediately to fulfil the requirements with regard to light propagation.
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 it has 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 impor-tant for the emission of light in the abovementioned colours.

If light is to be generated only in the said four col-ours, 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.
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 of semiconductor 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 prescribed requirements. The global photometric properties of the lighting device are determined by the cluster arrange-ment.
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 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 at an airport 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 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 semicon-ductor 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 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.
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 such that it satisfies in any case the requirements, already mentioned at the beginning, occurring in airport operation.
If the outside of the cover plate is easy to clean 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.
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 approximately corresponds to that of the cover plate. Optical losses on the transi-tion 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 l0 formed by the clusters, not every failure of an individ-ual 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.
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 projec-tions, 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 mechani-cal, specifically static and dynamic loads, and thermal loads resulting from the requirement for thermal dissi-pation. 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.
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.
As already set forth above at the appropriate juncture, the lighting device according to the invention can be provided for signalling on as well as designating and marking traffic areas in airports, for example runways, taxiways and the like. It can be designed straight away in accordance with the standards valid in air traffic and for airports, for example ICAO, FAA, DOT, CIE, MIL-C-25050.
In one configuration of the lighting device as a flush-marker light, the absence of cavities ensures that, when driven over by a vehicle or an aircraft, the light-ing 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.
It is also possible to configure the lighting device according to the invention such that it can be used to designate and mark traffic areas in road traffic, for example for roadway direction displays, roadway lane markings, speed restriction displays and the like.
Moreover, it is also possible to consider a configuration of the lighting device according to the invention for operating in navigation, for example for beacon lights, navigation channel displays, buoy markings and the like.
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. The material provided in the case of the lighting device according to the invention can be formed into virtually any shape with a low outlay. It can, moreover, serve as a thermal conductor, 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 insula-tor by selecting the material which can now be used, no costly separate insulator is required. A recyclable plastic can be used for the 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.
In accordance with this invention, there is provided a flush-marker light for signalling on and identifying traffic areas, having light sources designed as semiconductor elements, different semiconductor elements being provided in the form of clusters which in each case emit light of different colours, characterized in that the flush-marker light is suitably designed as an airport flush-marker light to be rolled over by aircraft and is intended for lighting take-off runways, landing runways, taxiways and has a control device with a pulse-width-modulation device by means of which the electrical energy fed to the semiconductor elements are regulated, and the intensity of the light emission of the semiconductor elements are thereby varied in a controlled fashion.
The invention is explained in more detail below with the aid of exemplary embodiments and with reference to 14a 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 invention;
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 systems;
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.
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.
All 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 1.
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 ; 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 aspher-ical 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 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 correspond 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.
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.
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 configuration 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.
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.
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 pro-vided.

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.
Loads and stresses introduced onto the cassette are transferred onto the roadway by means of the holding part 21. These stresses are static and dynamic 20 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, green 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 virtually in 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 lighting devices. The reason for this is that red, green and blue are arranged in the colour spectrum approximately at the corners of a triangle 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 the triangle which is to be seen in Figure 18 and corresponds to the said stan-dards.
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 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 accor-dance 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 19.
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 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 repre-sents an output power of the pulse-width modulation device 24 with a low intensity, and whose lower part represents 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.
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 l0 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 signals from 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 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

CLAIMS:

1. Flush-marker light for signalling on and identifying traffic areas, having light sources designed as semiconductor elements (1), different semiconductor elements (1) being provided in the form of clusters which in each case emit light of different colours, characterized in that the flush-marker light is suitably designed as an airport flush-marker light to be rolled over by aircraft and is intended for lighting take-off runways, landing runways, taxiways and has a control device (22) with a pulse-width-modulation device (24) by means of which the electrical energy fed to the semiconductor elements (1) are regulated, and the intensity of the light emission of the semiconductor elements (1) are thereby varied in a controlled fashion.

2. Flush-marker light according to Claim 1, in which the semiconductor elements (1) are light-emitting diodes (LEDs).

3. Flush-marker light according to Claim 1, in which the semiconductor elements (1) are light-emitting polymers.

4. Flush-marker light according to any one of Claims 1 to 3, in which the emitted light of different semiconductor elements (1) is mixed at will by means of the control device (22).

5. Flush-marker light according to any one of Claims 1 to 4, which is switched by means of its control device (22) which serves the purpose of control and power supply.

6. Flush-marker light according to any one of Claims 1 to 5, whose control device (22) has an electronic light regulator.

7. Flush-marker light according to any one of Claims 1 to 6, whose control device (22) is connected for signalling purposes to a central unit by means of a power supply line (37) or a separate electric or optical data line (36).

8. Flush-marker light according to any one of Claims 1 to 6, whose control device (22) is connected for signalling purposes to a central unit by means of a power supply line (37) and a separate electric or optical data line (36).

9. Flush-marker light according to any one of Claims 1 to 8, by means of whose control device (22) the light is selectably emitted in a directional plurality of directions.

10. Flush-marker light according to any one of Claims 1 to 9, by means of whose control device (22) the intensity of emission and the number of the semiconductor elements (1) emitting light of different colour is set such that light of arbitrary colour is emitted with arbitrary intensity by means of the flush-marker light.

11. Flush-marker light according to any one of Claims 1 to 10, by means of whose control device (22) a specific sequence of off and different on operating states are set.

12. Flush-marker light according to any one of Claims 1 to 11, by means of whose control device (22) the operating state and the serviceability of the semiconductor elements (1) are monitored.

13. Flush-marker light according to any one of Claims 1 to 12, which has semiconductor elements (1) which emit red, green and blue light and are arranged alternately.

14. Flush-marker light according to any one of Claims 1 to 12, which has semiconductor elements (1) which emit red and green light and are arranged alternately.

15. Flush-marker light according to any one of Claims 1 to 14, in which mutually adjacent semiconductor element rows are arranged offset from one another.

16. Flush-marker light according to any one of Claims 1 to 15, in which 2 to 200 semiconductor elements (1) form a cluster (3).

17. Flush-marker light according to any one of Claims 1 to 15, in which 2 to 30 semiconductor elements (1) form a cluster (3).

18. Flush-marker light according to any one of Claims 1 to 17 which is designed as a cluster arrangement made from a plurality of individual clusters (3).

19. Flush-marker light according to Claim 18, in which 1 to 30 clusters (3) form a cluster arrangement (11, 12).

20. Flush-marker light according to Claim 18 in which 1 to 16 clusters (3) form a cluster arrangement (11, 12).

21. Flush-marker light according to any one of Claims 1 to 20, in which the semiconductor elements (1) of a cluster (3) are arranged on a common substrate (4).

22. Flush-marker light according to any one of Claims 1 to 21, whose individual semiconductor elements (1) are designed without holders.

23. Flush-marker light according to Claim 21 or 22, in which the substrate (4) holding the semiconductor elements (1) is provided on its side facing the semiconductor elements (1) with a layer (5) made from a reflecting material.

24. Flush-marker light according to any one of Claims 1 to 23, 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.

25. Flush-marker light according to any one of Claims 21 to 24, the dimensions of whose radiation exit surface (6) correspond approximately to the area of the substrate (4) holding the semiconductor elements (1).

26. Flush-marker light according to any one of Claims 1 to 25, 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.

27. Flush-marker light according to any one of Claims 1 to 25, which is of bidirectional design and has two cluster arrangements (11, 12) which emit light in mutually inclined directions.

28. Flush-marker light according to Claim 26 or 27, in which each cluster arrangement (11, 12) has a plurality of clusters (3) arranged next to one another, mutually adjacent clusters (3) enclosing an angle of less than 180 degrees in each case.

29. Flush-marker light according to any one of Claims 1 to 25 which is of omnidirectional design and of curved design and has cluster arrangements forming a circle or a cylinder envelope.

30. Flush-marker light according to any one of Claims 1 to 29, whose semiconductor elements (1) are arranged in rows and columns.

31. Flush-marker light according to any one of Claims 1 to 29, whose semiconductor elements (1) are arranged in circles or cylinders.

32. Flush-marker light according to any one of Claims 1 to 31, whose semiconductor elements have an emitting section (2) in the shape of an aspherical lens.

33. Flush-marker light according to any one of Claims 1 to 32, in which the semiconductor elements (1) are constructed from an inorganic or organic material.

34. Flush-marker light according to any one of Claims 1 to 32, in which the semiconductor elements (1) are constructed from plastic.

35. Flush-marker light according to any one of Claims 1 to 34, in which the clusters (3) form a compact unit with a housing (15) of the flush-marker light.

36. Flush-marker light according to any one of Claims 1 to 35, in which there is arranged in front of the semi-conductor elements (1) a cover plate by means of which the beams emitted by the semiconductor elements (1) is influenced optically.

37. Flush-marker light according to Claim 36, in which the beams can be focused and directed by means of the cover plate (7).

38. Flush-marker light according to Claim 35 or 36, in which an optical device for beam diffraction or total reflection is assigned to the semiconductor elements (1).

39. Flush-marker light according to Claim 35 or 36, in which an optical device for beam diffraction and total reflection is assigned to the semiconductor elements (1).

40. Flush-marker light according to any one of Claims 36 to 39, in which the outside of the cover plate (7) is easily cleaned and cured.

41. Flush-marker light according to Claim 40, in which the outside of the cover plate (7) is coated.

42. Flush-marker light according to any one of Claims 1 to 41, whose semiconductor elements (1) are arranged embedded in a filler body (8).

43. Flush-marker light according to Claim 42, in which the filler body (8) of the semiconductor elements (1) has a cutout (9) at their active surface or light exit aperture (2).

44. Flush-marker light according to Claim 42 or 43, whose filler body (8) is constructed from a transparent material, the refractive index of which corresponds approximately to that of the cover plate (7).

45. Flush-marker light according to Claim 44, in which the transparent material is an epoxy resin.

46. Flush-marker light according to any one of Claims 1 to 45, in which one or more clusters (3) of the flush-marker light comprise an exchangeable sub-unit.

47. Flush-marker light according to Claim 46, in which the exchangeable sub-unit is a cassette (20) which is type coded.

48. Flush-marker light according to Claim 47, in which there are constructed on the outside of the cassette (20) projections and depressions, respectively, which are assigned to depressions and projections, respectively, on the holder (21), accommodating the cassette (20), of the flush-marker light.

49. Flush-marker light according to any one of Claims 46 to 48, in which the cassette (20) has a housing which is filled entirely or partially with an electrically nonconducting material.

50. Flush-marker light according to any one of Claims 46 to 49, in which a nonconducting filler is added to the electrically nonconducting material.

51. Flush-marker light according to Claim 50, in which the nonconducting filler is glass.

52. Flush-marker light according to any one of Claims 46 to 51, in which one wall or a plurality of walls of the housing of the cassette (20) form a thermal conductor.

53. Flush-marker light according to any one of Claims 46 to 51, in which a bottom wall of the housing of the cassette (20) forms a thermal conductor.

54. Flush-marker light according to Claim 52 or 53, in which the thermal conductor is stainless steel.

55. Flush-marker light according to Claim 52 or 53, in which the thermal conductor is aluminum.

56. Flush-marker light according to any one of Claims 46 to 55, in which the outside of the cassette (20) is provided with a hardened portion, at least on the regions principally stressed.

57. Flush-marker light according to any one of Claims 1 to 56, whose housing is constructed from a nonmetallic and electrically nonconducting material.