WO2008093198A2

WO2008093198A2 - A system for regulating a light beam emitted by a plurality of light sources configured in parallel

Info

Publication number: WO2008093198A2
Application number: PCT/IB2008/000180
Authority: WO
Inventors: Giovanni Cannistra'; Gianni Facchini
Original assignee: O.C.E.M. S.P.A.
Priority date: 2007-01-31
Filing date: 2008-01-28
Publication date: 2008-08-07
Also published as: WO2008093198A3

Abstract

A system for regulating a light beam emitted by a plurality of lighting sources configured in parallel, comprising: a conversion apparatus (APP) destined to provide at output an alternating voltage as a function of an external signal (EXT); and the plurality of lighting sources (Sl1..., SIJ,..., SIN) located in parallel with respect to the output terminals (GH) of the conversion apparatus (APP), destined each to emit a light beam having an intensity which is a function of the alternating voltage generated by the conversion apparatus (APP).

Description

A SYSTEM FOR REGULATING A LIGHT BEAM EMITTED BY A PLURALITY OF LIGHT SOURCES CONFIGURED IN PARALLEL

TECHNICAL FIELD

The invention relates to the technical sector of systems for regulating a light beam emitted by a plurality of annexed light sources configured in parallel, with special reference to airport applications.

BACKGROUND ART

Airport runways are illuminated by pluralities of sources configured in series or parallel in relative supply circuits, sometimes several kilometres long and supplied in alternating current via a relative network through a coupling transformer.

Circuits having configured parallel charges are constituted by a line connected to the secondary winding of the coupling transformer, to which line the light sources are connected; the light sources each comprise: a transformer TV having the primary winding connected to the line; an auxiliary device supplied by the secondary of the transformer TV, for supplying in output a current having a fixed- frequency square unipolar waveform and a variable duty cycle according to the lighting specifications demanded on the runway; and one or more LEDs reciprocally arranged in series or parallel and supplied by the auxiliary device with the aforementioned current pulsating between zero and the relative nominal current value. As an expert in the sector knows, in this case the duty cycle represents the ratio of the conduction time duration to the cycle time duration of the waveform of the current circulating on the diodes; in other words, it identifies the mean current value supplied on the LED diodes, directly connected to the level of light intensity emitted thereby.

In this context, the existing provisions in the airport sector require, for light sources, a light intensity defined on the basis of a succession of minimum values to be respected, which according to a known standard are, for example, those which would be obtained by applying current values of 2.8, 3.4, 4.1 , 5.2 and 6.6 amperes to an incandescent light bulb of known type. Thus different minimum luminosity values are defined with which to illuminate runways according to their degree of visibility (dusk light, night-time, poor weather conditions etc.). It is there of considerable importance, in terms of safety and respect for the provisions in force , to make a correct transmission relating to a degree of lighting required on the runway between a remote unit serving for the purpose, such as the control tower, and each light source.

At present the auxiliary devices communicate with the control tower by means of PLC (Power Line Communication) waves transmitted on the supply circuits, thus regulating the duty cycle of the current supplied to the respective LEDs, with a consequent variation of the light intensity emitted thereby according to the standards mentioned herein above and the contingent light conditions on the runway.

Nevertheless, the information signal sent by PLC waves has by its own nature a limited power, so that it is sensitive to leaks and electromagnetic interferences involving the line, in a greater amount as the light source supply circuit grows; as a direct consequence, the signal can arrive at some light sources in an unintelligible state, and/or might be interpreted wrongly by the sources. DISCLOSURE OF INVENTION

In the light of the above, an aim of the present invention is to provide a system for regulating the light beam emitted by a plurality of light sources in parallel, which enables the transmission of data relating to the degree of lighting requested on the runway and directed to the light sources, and which is reliable and guarantees intelligibility of the data sent along even long circuits.

A further aim of the invention consists in providing a system which is based on a simple concept and involves relatively contained costs with respect to the objectives set therefor.

The aims are attained by providing a system for regulating the light beam emitted by a plurality of light sources in parallel, comprising: a conversion apparatus powered by an external supply source, destined to provide on output terminals thereof an alternating voltage having presettable characteristics in accordance with an external signal received at the input thereof, which signal represents a degree of illumination required on the runway; and the cited plurality of light sources located functionally parallel with respect to the output terminals of the conversion apparatus, destined each to emit a light beam having an intensity which is a function of the alternating voltage generated by the conversion apparatus on the relative output terminals.

The above-described system advantageously obviates the above- described drawbacks in prior art applications: the conversion apparatus provides, on the output terminals thereof, a voltage which not only supplies the light source circuit, but also exhibits, in the characteristics of its waveform and/or frequency, the data contents of the external signal received at the input of the conversion apparatus concerning the degree of lighting required on the runway; consequently, the light -A-

sources regulate the light beam emitted by the LEDs, thus satisfying the demands of the control tower. The signal, thus associated to the profile of the waveform and/or the frequency of the supply voltage to the output terminals of the conversion apparatus, is almost insensitive to electromagnetic interference and leakage along the light source supply line; for this reason, the reliability of the system of the invention is advantageously guaranteed for circuits stretching out for as long as several kilometres.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the invention which do not emerge from the above shall be better evidenced in the following, in agreement with what is set out in the claims and illustrated in the accompanying figures of the drawings, in which:

figure 1 is the functional electrical diagram of a regulation system of a light beam emitted by a plurality of light sources of the invention;

figure 1A is the functional electrical diagram of a regulation system in agreement with a variant of the present invention;

figures 2A, 2B, 2C, 2D, 2E are examples of corresponding waveforms of voltage produced in the system of figure 1 in a third functioning mode;

figure 3 represents a relative waveform of voltage generated by the system of figure 1 in a fourth functioning mode. BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the accompanying figures of the drawings, APP denotes a conversion apparatus powered, for example, by a three- phase supply network RM, which receives in input an external signal EXT transmitted by an external unit (not illustrated), i.e. the control tower of the airport, and substantially comprises: an AC/DC rectifier bridge of known type, supplied by the RM network, which converts the three phase alternating voltage (or alternatively single phase) into a direct voltage; a filter arranged functionally downstream of the AC/DC rectifier bridge, constituted for example by an inductance L and a condenser C, correctly dimensioned; and a DC/AC inverter, also of known type, arranged downstream of the filter, for transforming the direct voltage again into an alternating voltage having pre-settable characteristics (frequency and/or duration of the positive half-wave with respect to the negative half-wave and/or profile of the relative waveform) according to the data contents of the external signal EXT. The DC/AC inverter, for example, is constituted by an IGBT switch bridge commanded by a controller CE via corresponding signals Ki, K₂, K₃, K₄ according to the external signal EXT.

The output terminals GH of the conversion apparatus APP are functionally connected to an electric line A by interposition of a suitable coupling transformer T (which might alternatively be arranged upstream of the conversion apparatus APP); a plurality of light sources Sh, ..., SIj SI_N, of known type, are derived from the line A, each of the light sources comprising, as already mentioned: a transformer TV having a primary derived from the line A; an auxiliary device Dj, supplied by the secondary of the transformer TV, for supplying in output a unipolar impressed current having, for example, a square waveform, fixed frequency and variable duty cycle according to the information content of the external signal EXT associated to the alternating voltage supplied at the output terminals GH of the conversion apparatus APP, as will be more fully explained herein below; and one or more LEDs Lj arranged in series or parallel to one another, supplied by the auxiliary device Dj, with a pulsating current between zero and the relative nominal current.

In a first functioning mode of the system of the invention, the conversion apparatus APP has the task of generating in output an alternating voltage (in the example having a square wave) of variable frequency as a function of the data contents of the external signal EXT, representing the degree of illumination required on the runway. According to the degree of illumination required, the auxiliary devices D₁, ..., Dj, ..., D_N consequently have the task of regulating the duty cycle of the current which is to be supplied to the corresponding diodes L₁, ..., Lj , LN, i.e. the mean current value for obtaining the illumination of the runway in conformity with the data contents of the external signal EXT.

In other words, the data content of the signal EXT, for example digital and coming from a remote apparatus, such as the control tower, is thus associated to the frequency of the supply voltage of the light sources

Sl₁ SIj SI_N, and decoded therefrom; there is also a biunique correspondence between the values of the data signal EXT and the values of the frequency of the supply voltage.

In a second operating mode of the system, the conversion apparatus APP can generate an alternating voltage having a fixed frequency and a duration which is relative to the positive half-wave, with respect to the negative half-wave, a function of the values taken on by the external signal EXT; there follows a corresponding regulation of the duty cycle of the current which has to be supplied to the corresponding diodes L₁, ..., Lj LN by the auxiliary devices D₁ Dj, ... D_N. In a third operating mode of the system, the conversion apparatus APP has the task of generating an alternating voltage at the output terminals GH which is distinguished by localised alterations in time of the relative waveform, for example corresponding "voltage sags", i.e. sharp voltage drops, limited in time and variable in number according to the values of the external signal EXT (figures 2A, 2B, 2C, 2D, 2E). This is obtained with predetermined sequences of opening and closing the switches of the DC/AC inverter, regulated by the controller CE by means of the corresponding signals Ki, K₂, K₃, K₄.

Purely by way of example, figures 2A, 2B, 2C, 2D, 2E show corresponding waveforms of the alternating voltage present at the output GH of the apparatus APP, distinguished in the first reference half-period respectively by one, two, three, four, five "voltage sags", indicating corresponding light flow levels which have to be emitted by the LEDs of the light sources Sh SIj SI_N following the contingent lighting requirements on the runway. In the illustrated example, the auxiliary devices D₁, ..., Dj D_N have the task of performing a count of the number of voltage sags in a predetermined time interval of the wave form of the alternating voltage supplied on the output terminals GH of the apparatus APP, which time interval in the illustrated example relates to a relative half-period; the number of voltage sags recorded by the above-mentioned auxiliary devices Di

Dj D_N, in the above-cited time interval establishes the duty cycle of the current which has to be supplied to the corresponding diodes Li, ..., Lj L_N, i.e. the relative mean current value for obtaining optimal illumination of the runway in conformity with the data content of the external signal EXT.

In a fourth operating mode of the invention, a single voltage sag can be generated by the apparatus APP at a moment in time which can be variable within a predetermined time interval as a function of the data contents of the external signal EXT; in the example illustrated in figure 3, this time interval coincides with a half-period of the voltage supplied to the output terminals GH of the apparatus APP. Thus, on the basis of the relative position taken on by the voltage sag within the time interval, the auxiliary devices Di Dj, ..., D_N have the task of regulating the duty cycle of the current which is to be supplied to the corresponding diodes L₁ Lj L_N.

Alternatively, the above-described third and fourth operating modes can be actuated using systems according to the variant illustrated in figure 1A, described herein below.

With reference to figure 1A, the conversion apparatus APP is supplied by a single-phase network RM via a coupling transformer T and receives in input the external signal EXT coming, for example, from the control tower and as previously mentioned representing the degree of lighting required for the runway; the conversion apparatus APP comprises, substantially: two switches, a first Ii and a second I₂, arranged respectively in series at the relative input terminals; a third switch I₃ arranged downstream of the above-mentioned switches I₁, I₂ and in parallel on the relative output terminals GH; and finally an electronic controller CE, which receives in input the external signal EXT and consequently regulates the opening/closing of the switches I₁, I₂, I₃ by means of corresponding signals K₁, K₂, K₃.

The above-described third and fourth operating modes can be obtained with predetermined sequences of opening and closing of the switches I₁, I₂, I₃ commanded by the controller CE; by way of example, starting from the configuration in which the first I₁ and the second I₂ switches are closed and the third I₃ is open, the generation of a voltage sag at the terminals GH of the apparatus APP includes, in succession: the opening of the first switch I₁ and the second switch I₂, the closure for a limited time of the third switch I₃ in order to short-circuit the outlet terminals GH of the apparatus GH itself, thus newly the opening of the third switch I₃ and then the closing of the first switch I₁ and the second switch I₂.

All four operating modes described lead to the same technical- functional advantages, as mentioned herein above, and very effectively resolve the drawbacks in the prior art; the system of the invention advantageously leads to relatively contained costs with respect to the advantages obtained.

Alternatively to the main embodiment described in figure 1 , the conversion apparatus APP can be supplied by a direct voltage source instead of alternated three-phase or single-phase voltage; in this case the AC/DC rectifier bridge is useless, so that the conversion apparatus APP would be substantially constituted by the DC/AC inverter device (not illustrated).

The above description is provided by way of non-limiting example; variations of a practical-applicational nature all fall within the ambit of protection as described above and as claimed herein below.

Claims

1). A system for regulating a light beam emitted by a plurality of lighting sources arranged in parallel, characterised in that it comprises: a conversion apparatus (APP) powered by means of an external supply source (RM), destined to provide, at output terminals (GH) thereof, an alternating voltage having pre-settable characteristics as a function of an external signal (EXT) received at an input thereof; and the plurality of lighting sources (Sh SIj, ..., SI_N), located functionally in parallel with respect to the output terminals (GH) of the conversion apparatus (APP) and powered by the conversion apparatus (APP), destined each to emit a light beam having an intensity which is a function of the alternating voltage generated by the conversion apparatus (APP) on the output terminals (GH).

2). The system of claim 1 , in which the external supply source (RM) dispenses an alternating voltage, characterised in that 'the* conversion apparatus (APP) comprises: an (AC/DC) rectifier device, powered by the external supply source (RM), for converting the alternating voltage dispensed by the external supply source (RM) into a direct voltage made available to the output terminals thereof; and a (DC/AC) inverter device for transformation of the direct voltage, dispensed by the (AC/DC) rectifier device, into the alternating voltage having pre-settable characteristics supplied to the output terminals (GH) of the conversion apparatus (APP).

3). The system of claim 1 , in which the external supply source (RM) dispenses a direct voltage, characterised in that the conversion apparatus (APP) comprises: a (DC/AC) inverter device for converting the direct voltage dispensed by the external supply source (RM) into the alternating voltage having pre-settable characteristics supplied to the output terminals (GH) of the conversion apparatus (APP).

4). The system of claim 1 , characterised in that the conversion apparatus (APP) comprises: a first current switch (U) and a second current switch (I₂), located in series respectively at each relative input terminal powered by means of the supply source (RM); and a third current switch (I₃) arranged downstream of the first switch (U) and the second switch (I₂), functionally derived between the output terminals (GH) of the conversion apparatus (APP), the switches (li, I₂, I₃) being operated in mutually suitable phase relation in order to generate the localised alterations in time of the voltage waveform supplied by the conversion apparatus (APP) to the output terminals (GH).

5). The system of one of claims from 1 to 3, characterised in that the conversion apparatus (APP) supplies to the output terminals (GH) thereof an alternating voltage which is distinguished by one or more localised alterations in time of the relative waveform, which alterations are a function of the external signal (EXT) and are concentrated internally of at least a predetermined time interval.

6). The system of claim 4 or 5, characterised in that the one or more localised alterations in time of the waveform of the alternating voltage are made according to a variable number which is a function of the external signal (EXT).

7). The system of claim 4 or 5 or 6, characterised in that one or more of the localised alterations in time of the wave form of the alternating voltage are made according to time instants which are variable as a function of the external signal (EXT) within the predetermined time interval. 8). The system of claim 4 or 5 or 6 or 7, characterised in that one or more of the localised alterations in time of the waveform of the alternating voltage are identified by sharp drops in voltage, lasting for a limited time.

9). The system of one of claims from 1 to 3, characterised in that the conversion apparatus (APP) provides on the output terminals (GH) an alternating voltage which varies in frequency as a function of the external system (EXT).

10). The system of one of claims from 1 to 3, characterised in that the conversion apparatus (APP) provides on the output terminals (GH) an alternating voltage the half-waves of which have a variable duration as a function of the external signal (EXT).