EP0015888B1 - Device for the sequential operation of flashing lights - Google Patents

Description

The present invention relates to a system for controlling several flashing lights in repeated sequences.

Flashing lights are spotlights that emit very short flashes of light. Such lights are used in particular as light beacons for the visual guidance of aircraft to the runways. These lights are installed at ground level or near ground level to indicate the route to be followed towards the runway or the final approach. The lights of each light group are placed and oriented so that they can be easily identified from the previous group and that they can be followed by an approaching aircraft under conditions equal to or greater than the approach minima considered. The device can be curvilinear, rectilinear or a combination of the two, as required. The runway guidance lighting may end where an approved approach lighting begins or at a distance from the landing threshold that is compatible with authorized visibility minima to allow visual identification with respect to the environment. of the track. The initial portion consists of groups of lights to mark the segments of the approach path starting at a point easily visible from a final approach position mark. These groups can be placed at sufficiently close intervals (approximately 1,600 meters, i.e. 1 mile) to provide continuous guidance. A group includes at least three flashing lights arranged in a line or in a group and can be reinforced by fixed incandescent lights, as required. If possible, groups of lights must sequentially emit flashes towards the runways.

Up to now, the lighting of beacon flashing lights has been controlled by an organized system for transmitting control pulses to the various lights by means of one or more specially provided control lines, distinct from the power distribution line. Each light is provided with an individual box comprising an ignition device responding to the control pulses and a high voltage energy storage device (high voltage capacitors) connected to the power supply line. The possible positive repetition of the proper functioning of the lights requires a special transmission line between the lights and the control center. The energy level of the light flashes is adjusted from the control tower by means of another special transmission line. Such a control system is complicated and costly to install by the fact that it requires the installation of several transmission lines between the control tower, the control station and the lights and that it requires the installation of high voltage energy storage devices using special capacitors. Between two successive flashes of the same spotlight, the corresponding capacitor is gradually recharged by taking current from the power supply line. When the flash occurs, the capacitor discharges instantly through the lamp, producing a very brief but very intense light flash.

The invention, defined in claim 1, solves the problem of providing a system for sequentially controlling the lighting of strobe lights, which is simpler and notably less expensive than the known system. It aims at an original organization of the control center and the ignition circuits thanks to which the system only requires the installation of the only power distribution line between the control center and the strobe lights in order to transmit the light start orders.

The control system according to the invention comprises a control center in which means are provided for detecting and counting the alternations of the supply voltage in order to produce on the energy distribution line sequences of pulsed voltage waves which contain the orders for lighting the lights. Each individual fire ignition circuit comprises means for interpreting these pulsed voltage waves in order to derive therefrom unambiguously and reliably the ignition signal specific to the corresponding fire.

The advantage of the system according to the invention is that it eliminates the installation of traditional control and signaling lines, all the sequencing and energy level control of the light flashes as well as the positive repetition of the good functioning of the lights being centralized at the control center. In addition, the high voltage capacitors usually provided for energy storage as well as the charge and protection circuits relating thereto are also eliminated.

• la figure 1 est un schéma d'ensemble du système suivant l'invention,
• la figure 2 est un schéma d'un exemple de mode de réalisation du sous-ensemble de logique du central de commande suivant l'invention,
• la figure 3 est un schéma d'un circuit d'allumage individuel de feu suivant l'invention.

A more detailed description of the invention is given in the following on an exemplary embodiment illustrated in the accompanying drawings in which:

• FIG. 1 is an overall diagram of the system according to the invention,
• FIG. 2 is a diagram of an exemplary embodiment of the logic sub-assembly of the control center according to the invention,
• Figure 3 is a diagram of an individual fire ignition circuit according to the invention.

The system is shown as a whole in FIG. 1. The various flashing lights P are connected to the power distribution line 100 by means of individual boxes 1 each containing the ignition circuit of the associated light. The distribution line 100 connects the boxes 1 to a control center 2 itself connected to a supply voltage source Vo by the line 110 on the one hand, and to the control tower TC by line 200 on the other hand. The object of the system according to the invention is to control the sequence of lighting of the lights, in a safe and reliable manner, using only the distribution line itself. It is to achieve this goal that the control center and the individual ignition circuits are organized.

The control center is organized to control the timing of lighting of the P lights in synchronism with some of the positive alternations of the supply voltage. The central includes a thyristor 4 connected in series with the distribution line 100 so that, each time it is started, it allows a positive alternation of the voltage to pass. A second thyristor 5 is connected in bypass on the distribution line with its cathode connected to the cathode of thyristor 4. When it is started, thyristor 5 delivers a current limited by resistance R, which allows the short-circuit from line 100, but not from source Vo. Upstream of thyristor 4 is connected the input of a subset of a logic unit 20 having the function of generating two trains of pulses MNSP and MNSN for controlling the ignition of thyristors 4 and 5 in rigorous synchronism with certain alternations of the voltage Vo.

FIG. 2 is a diagram of the sub-assembly of the logic unit 20 specially organized according to the invention. The other subsets assigned to the execution of conventional tasks outside the scope of the invention are not shown. The step-down transformer 21 has its primary connected to the voltage Vo and its secondary winding 22 with central outlet 23 has its terminals connected to the bases of two transistors 24, 25 through a diode and a resistor in series, respectively the elements 26, 27 for the transistor 24 and the elements 28, 29 for the transistor 25. The bases of these transistors are thus driven in phase opposition. The collectors of the transistors 24, 25 are connected to two inverter circuits 31, 32; at the outputs of these appear pulses MNSP and MNSN which are respective images of the positive and negative alternations of the voltage Vo. Capacities 33, 34 make up, with resistors 27, 29, time constant circuits which advantageously provide the MNSP and MNSN pulses with a small phase shift, for example 15 ° and 105 ° respectively, relative to the voltage Vo. We will return to the question of this phase shift later.

The train of MNSP pulses is applied by the line 310 to the trigger of the thyristor 4 through an amplifier element 30. In the simple system thus described, the thyristor 4 is thus primed during the duration of each MNSP pulse in synchronism with the positive alternations of the voltage Vo. In a more complex system where it is required to be able to extinguish some of the lights installed, the train of pulses MNSP is also processed in logic unit 20 to detect among the set of positive half-waves of the voltage Vo, the active half-waves during which the splinters must occur. This processing function is symbolized in FIG. 2 by the dotted block denoted 40, which consists of a processing subset falling within the competence of a person skilled in the art.

The distribution line therefore happens to be the seat of pulsed voltage waves which contain the orders for lighting the lights. These waves are interpreted in the individual ignition circuit of each light, as will be seen below, in order to derive therefrom the ignition control signal specific to this light.

The MNSP pulse train activates a binary counter 35 with which two comparators 36, 37 are associated. These each receive the content of the counter 35 in order to compare this content with a distinct threshold. The threshold N1 fixed to comparator 36 represents the number of lights controlled in sequence; the threshold N2 at comparator 37 represents the ratio of the interval between the start of two successive sequences to the period of the supply voltage Vo (N2 is always greater than N1).

Comparators 36 and 37 are connected to produce three signals: a signal A when the content of the counter 35 is less than N1, a signal B when the content of the counter is greater than N1 and a signal C when the content of the counter is equal to N2.

Signal A indicates that an active sequence is in progress, signal B indicates a rest interval between two sequences, and signal C indicates that the first light must be re-lit in the following sequence. Signals B and C are combined in an AND gate 38 to reset counter 35 to zero via line 380.

The circuit made up of elements 41-43 serves as a witness “out of sequence in phase with the negative half-waves of the voltage Vo. The inverter 41 receives the signal A and applies its inverse A to an input of the AND gate 42. The second input thereof receives the MNSN pulses present on the line 320 coming from the inverter 32. The signal appearing at the output of gate 42, amplified in amplifier 43, is applied to the trigger of thyristor 5. Thus, during the rest intervals between successive sequences, thyristor 5 is primed and short-circuits the line distribution 100 during negative half-cycles. This short-circuit has the effect of resetting all the individual ignition circuits of the lights to zero, as will be seen later.

The rectangle noted 6 in FIG. 1 represents a series impedance connected to serve as a current intensity limiter on the distribution line 100. This impedance 6 is connected to be switchable under the control of a signal applied to line 210 by the logic unit 20 in response to an energy level order received from the control tower on line 200.

In FIG. 1, the device 50 is a circuit switch controlled from the control tower TC via the line 220, and the devices denoted F are usual protection fuses.

• a) nombre de feux à éclats commandés dans une séquence active,
• b) intervalle entre deux éclats successifs à l'intérieur d'une séquence active, en multiples entiers de la période de la tension d'alimentation,
• c) intervalle entre deux séquences actives successives, en multiples entiers de la période de la tension d'alimentation.

The organization of the control center according to the invention makes it possible, by simple modification of the thresholds N1 and N2 fixed to the comparators 36 and 37, to easily adapt the system to the operating conditions:

• a) number of flashing lights controlled in an active sequence,
• b) interval between two successive flashes within an active sequence, in whole multiples of the period of the supply voltage,
• c) interval between two successive active sequences, in integer multiples of the period of the supply voltage.

• a) établissement de la concordance entre le niveau réel du courant de ligne et l'ordre présent sur la ligne 200,
• b) établissement de la concordance entre le courant de ligne instantané et l'ordre d'allumage du thyristor 4,
• c) la localisation géographique de feux défectueux,
• d) la détection d'un court-circuit de la ligne 100,
• e) le comptage du nombre de feux défectueux et la détermination de ce que des feux défectueux sont des feux successifs ou non.

The organization of the control center according to the invention also makes it possible to centralize the positive repetition function of the proper functioning of the system as a whole on the basis of the following information, available at the control center itself: the pulses MNSP and MNSN, the content of the counter 35 and a signal V _I representing the amplitude of the current in the distribution line, measured by a current measurement member represented by the block M in FIG. 1. This combined information constitutes a particularly rich source of data since it allows the execution of the following functions:

• a) establishment of the agreement between the actual level of line current and the order present on line 200,
• b) establishment of the agreement between the instantaneous line current and the ignition order of the thyristor 4,
• c) the geographical location of defective lights,
• d) the detection of a short circuit on line 100,
• e) counting the number of defective lights and determining whether or not defective lights are successive lights.

Reference will now be made to FIG. 3 to describe the organization of the individual light ignition circuit included in each box 1. As we have seen above, the light ignition orders are transmitted on the distribution line by repeated sequences of pulsed waves and it is therefore these pulsed waves that each individual fire ignition circuit must interpret in order to derive from them unambiguously and reliably the ignition signal specific to fire with corresponding flashes. Each ignition circuit 1 comprises, connected as a branch on the distribution line 100, an ignition logic 10 having the function of detecting and counting, during each sequence, the positive alternations of the voltage on the distribution line. The device 11 is a binary counter, the device 12 is a connected comparator for comparing the content of the counter 11 with a coded threshold N corresponding to the geographical position of the light with which the box is associated. The comparator 12 produces an ignition signal on line 120 when the content of the counter 11 is equal to the fixed threshold N, that is to say when the content of the counter 11 is the image of the geographical position of the light to be order at this time.

The counter 11 starts at zero with each new sequence and it progresses under the control of pulses generated in a pulse generator essentially comprising the transistors 13 and 14 connected in series. When the line voltage V100 is positive, this voltage is applied to the base of the transistor 13 through the input circuit 15-17: the transistor reaches saturation and causes the blocking of the transistor 14. Thus, when the voltage V100 is positive, the collector of transistor 14 (signal VLSP) is in the high state. When the voltage V100 is negative, the transistor 13 is blocked and the transistor 14 is saturated: the signal VLSP is then in the low state or logic level 0.

The elements of the circuit are chosen so that the VLSP signal exhibits a weak phase, for example 15 °, with respect to the voltage V100, which guarantees greater reliability and a better ignition efficiency of the lights given that the priming is then less sensitive to the instant of priming. This eliminates the need for individual adjustment as in the known devices.

The device 18 is an AND-NOT gate receiving the signal VLSP and a signal ÎNFR indicating that the content of the counter 11 is less than the threshold N fixed to the comparator 12. Thus, before attacking the counter 11 the signal VLSP is subjected to the condition to be concomitant with the presence of a content of the counter 11 less than N, which has the effect of preventing any inadvertent ignition of the fire. In the event of a fault, the light stops working.

• a) fiabilité maximum de l'amorçage et grande insensibilité aux variations de l'angle d'amorçage,
• b) condensateur de mémorisation de très faible valeur (typiquement 0,5 microfarad) ; cette valeur doit être juste suffisante pour entretenir la conduction du feu à éclats entre l'instant d'amorçage et celui où la tension de ligne atteint une valeur égale à la tension d'arc,
• c) possibilité de choisir un angle d'amorçage faible et de garantir simultanément la constance de l'énergie lumineuse des éclats sans exiger de précision et de stabilité excessives de l'angle d'amorçage.

Each fire is therefore started by the respective control pulse in each sequence. Between two successive flashes, a storage capacitor 7, connected in series with a resistor 8 on the line voltage V100, is gradually charged to the peak value and it remains charged by the presence of the diode 9. In this way, at the when the fire starts, it is lit under the maximum voltage and this ensures the following advantages:

• a) maximum ignition reliability and high insensitivity to variations in the ignition angle,
• b) very low value storage capacitor (typically 0.5 microfarad); this value must be just sufficient to maintain the conduction of the flashing light between the moment of ignition and that when the line voltage reaches a value equal to the arc voltage,
• c) possibility of choosing a small ignition angle and simultaneously guaranteeing the constancy of the light energy of the flakes without requiring excessive precision and stability of the ignition angle.

The counter 11 is reset to zero by detecting the absence of the negative half-waves of the voltage on the distribution line 100. It will be recalled that the negative half-waves are present on line 100 during each active sequence, when the thyristor 5 of the control center 2 (Fig. 1) is not primed. During the rest intervals between successive sequences, on the other hand, the primed thyristor 5 suppresses the negative half-waves on the line 100. The presence or absence of the negative half-waves on the distribution line 100 is detected by an optical coupler 44 thus comprising as is known per se, a light emitting diode coupled to a transistor. The negative half-waves of the voltage V100 saturate the transistor of the optical coupler 44, which has the effect of keeping the capacitor 45 practically discharged. The input of the inverter 46 is then in state 0, its output is in state 1 and the output of AND-NO gate 47 is in state 0. The reset input RS of counter 11 is therefore inactive.

At the end of an active sequence, when the negative half-waves are removed by the thyristor 5 of the control center, the transistor of the optical coupler 44 is blocked and the capacitor 45 is charged through the resistor 48. The inverter 46 and the door 47 tilt, bringing the output of the door 47 to state 1, which thus activates the RS input of the counter 11 and the latter is reset to zero. As soon as the negative half-waves reappear, the capacitor 45 discharges instantaneously through the resistor 49, the output of the gate 47 is returned to the state 0 and the counter 11 can start for a new counting cycle. The resistor 51 and the capacitor 52 serve to force the counter 11 to zero for a short period of time after power-up in order to avoid a random start of the counter.

Claims (3)

1. A control system for operating a plurality of flash lamps (P) in repeated sequences, said plurality of flash lamps being connected to a power distribution line through individual trigger circuits (1), with the power distribution line being connected across an alternating current power source through a control unit (2), characterized in that the control unit comprises

- a first controlled switch (4) connected in series with the power distribution line (100) for transmitting a positive half cycle of the power source voltage each time it is gated by a pulse being applied to its control electrode, said pulse corresponding to a triggering command for a respective flash lamp ;

- a second controlled switch (5) connected across the power distribution line with its cathode electrode connected to the cathode electrode of the first controlled switch thereby to short circuit the power distribution line each time it is gated by a pulse being applied to its control electrode ;

- detection means (20) for detecting the half cycles of the power source voltage and producing a first burst of pulses (MNSP) in which each pulse corresponds to a positive half cycle of the power voltage and a second burst of pulses (MNSN) in which each pulse corresponds to a negative half cycle of the power source voltage, the pulses of said first burst of pulses being applied to the control electrode of the first controlled switch (4) ;

- counting means (35, 36, 37) connected to accept said first burst of pulses from the detecting means for counting said pulses up to a number equal to the number of flash lamps to be operated in sequence, said counting means being further connected to produce a control signal when the number of said pulses is equal to said number of flash lamps to be operated in sequence ; and

- gating means (42) connected to accept the second burst of pulses from the detecting means and being responsive to the control signal from the counting means for transferring the second burst of pulses to the control electrode of said second controlled switch (5) thereby to short the power distribution line and suppress the negative half cycles of the voltage thereon during the time intervals between succeeding operation sequences.

2. The system according to claim 1, wherein each individual flash lamp trigger circuit (1) comprises first detecting means (10) for detecting the positive half cycles of the voltage on the power distribution line (100) from the control unit, said detecting means being connected across the power distribution line for producing a pulse in response to each occurrence of a positive half cycle of the voltage on the distribution line ;

- counting means (11, 12) connected to the output of said first detecting means for counting the pulses up to a predetermined number (N), distinct for each individual trigger circuit, and for producing a trigger control signal in response to the number of incoming pulses being equal to said predetermined number,

- second detecting means (44-52) for detecting the negative half cycles of the voltage on the power distribution line from the control unit, said detecting means being connected across the power distribution line for producing a reset signal (RS) for the counting means in response to the negative half cycles of the voltage on the distribution line being absent.

3. The system according to claim 2, wherein each individual trigger circuit (1) further comprises, connected across the flash lamp (P), storing means for the peak value of the voltage on the distribution line (100), said storing means comprising resistor and capacitor means (7, 8) connected in series, said storing means being further connected across the distribution line through a diode (9) connected in series with the flash lamp.

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