EP0271396A1 - Process and device for igniting discharge lamps - Google Patents

Process and device for igniting discharge lamps Download PDF

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Publication number
EP0271396A1
EP0271396A1 EP87402640A EP87402640A EP0271396A1 EP 0271396 A1 EP0271396 A1 EP 0271396A1 EP 87402640 A EP87402640 A EP 87402640A EP 87402640 A EP87402640 A EP 87402640A EP 0271396 A1 EP0271396 A1 EP 0271396A1
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EP
European Patent Office
Prior art keywords
lamp
frequency
pulses
circuit
value
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EP87402640A
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German (de)
French (fr)
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EP0271396B1 (en
Inventor
Pierre Perche
Marcel Perche
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PERCHE Ets
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PERCHE Ets
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
    • H05B41/288—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices and specially adapted for lamps without preheating electrodes, e.g. for high-intensity discharge lamps, high-pressure mercury or sodium lamps or low-pressure sodium lamps
    • H05B41/2881—Load circuits; Control thereof
    • H05B41/2882—Load circuits; Control thereof the control resulting from an action on the static converter
    • H05B41/2883—Load circuits; Control thereof the control resulting from an action on the static converter the controlled element being a DC/AC converter in the final stage, e.g. by harmonic mode starting

Definitions

  • the present invention relates to an electronic ignition method and device, in particular intended for supplying discharge lamps, with cold or hot cathode, from alternating current from the mains.
  • the present invention relates to a method and a device which, while retaining the principle of lighting the arc lamp, by virtue of the overvoltage created in a resonant circuit, by means of a switching power supply providing pulses of high frequency , allows the use of inductor windings, the value of which can be relatively imprecise and avoids the drawbacks of conventional solutions, while also providing great operational safety, in particular without the risk of overcurrent in the lamp circuit when it is switched on.
  • the object of the invention is also to ensure, in the event of a cut in the supply of the lamp, a safe re-ignition thereof.
  • the process considered, for the ignition of a discharge lamp mounted in a series resonant circuit comprising an inductor and a capacitor, the lamp being arranged in series with the inductor and in parallel on the capacitor, this resonant circuit being placed in the diagonal of a bridge at the terminals of which are supplied voltage pulses supplied by a power supply switching, is characterized in that it consists in varying the switching frequency of the supply pulses in a frequency range extending between two predetermined extreme values which surround the resonant frequency of the circuit or one of its harmonics according to a approximately linear law, respectively increasing then decreasing, with a given scanning period of this range, to adjust the angle of passage of the pulses measuring the ratio of the duration of these to their period to a constant and limited value so that that the current supplied to the lamp at each pulse is significantly reduced, then when the lamp is turned on thanks to the overvoltage created by the resonance of the circuit when the switching frequency is equal to the resonance frequency, to detect the passage of the current in the lamp to reduce the frequency of the pulses
  • the method according to the invention thus makes it possible, during each ignition sequence of the lamp, to ensure that the switching frequency or one of its harmonics varies regularly between a minimum frequency lower than the resonance frequency, and a maximum frequency greater than this resonant frequency, the angle of passage of the pulses, characterizing the amount of electrical energy passing through the electronic switches supplying the lamp according to the alternations of the supply current, being reduced to a value such that at ignition the overcurrent produced is always acceptable by the installation.
  • the invention also relates to a device for implementing the method, comprising a switching power supply consisting of a filtered and rectified voltage source, joined to the terminals of a bridge comprising in each of its branches electronic switches in pairs associated and in the diagonal of the bridge, a resonant circuit comprising a winding of inductor and a capacitor, the lamp being mounted in this diagonal in series with the inductor and in parallel on the capacitor, the switches being operated simultaneously so that each close when the others open, characterized in that the switching power supply includes a pulse generator arranged so that the pulses at the terminals of the bridge have a variable frequency which increases and decreases respectively, by scanning a range of frequencies extending between a lower value and a higher value at the resonant frequency of the circuit or one of its harmonics ues and whose angle of passage is small, so that at resonance the current passing through the lamp and the switches is limited to an admissible value, and in that it comprises in series with the lamp, a member detector of the passage of current in this lamp when
  • the electronic switches consist of MOS transistors receiving on their grid voltage pulses coming from the generator and causing the alternating conduction or blocking of these transistors.
  • the voltage pulses are supplied through the windings of an isolation transformer.
  • the pulse generator comprises a circuit supplying a sawtooth signal whose amplitude and period vary between two predetermined cutoff values, means for producing from this signal a variation in the switching frequency respectively increasing then decreasing and means for simultaneously adjusting the period and the duration of the voltage pulses supplied according to the variation in the switching frequency at a passage angle having a constant value across the whole range.
  • the detector of the ignition current in the lamp is constituted by a complementary inductor winding, arranged on a conductor joined to one of the electrodes of the lamp and in which the passage of the current after the ignition creates a voltage signal such that the variation in current thus detected acts on the pulse generator and reduces the switching frequency to its lower value in the range, where it is less than the resonance frequency, the angle of passage pulses being reduced simultaneously to a higher value.
  • references 1 and 2 designate the terminals of an alternating voltage source connected to an ignition circuit comprising a capacity 3 and a winding of inductor 4, respectively joined to electrodes 5 and 6 a discharge lamp 7 with a cold cathode.
  • the circuit includes an overvoltage generator 8, making it possible to create between these electrodes a very high ignition voltage such that an electric arc is established in the lamp.
  • the overvoltage generator 8 In operation, if the voltage between the electrodes 5 and 6 is of the order of 100 volts, the overvoltage generator 8 must be capable of creating a ignition voltage of the order of a thousand volts at least.
  • the lamp 7 is a hot cathode lamp where the electrodes 9 and 10 are, prior to ignition, traversed by a current raising their temperature, following the closing of a switch 11 called commonly "choke" mounted in parallel and placing these electrodes in short circuit.
  • the ignition voltage is still around 400 volts.
  • the winding of the inductor 4 must make it possible, when the electrodes of the lamp are short-circuited, to supply the latter with a suitable overvoltage capable of creating the arc between the electrodes.
  • this inductor due to the frequency of the supply current, usually alternating current at 50 periods, this inductor must have large dimensions, which in all cases results in a bulk and a high weight, ill-suited in particular for use. for discharge lamps or neon tubes for domestic or even industrial use.
  • FIGS 3 and 4 illustrate ignition systems also known in the art but with electronic operation.
  • the AC voltage source at 50 periods from the sector is connected to terminals 1 and 2 of the circuit, this voltage then being filtered at 12 and then rectified at 13 so as to supply terminals 15 and 16 of a capacitor 14 at the input d 'an appropriate rectified DC voltage cutting circuit.
  • a resonant circuit comprising a winding of inductor 19 and a capacitor 20.
  • the discharge lamp 23 is arranged at the terminals 21 and 22 of the latter.
  • the ignition voltage to be created at these terminals 21 and 22 is obtained by resonance of a series circuit constituted by a winding of inductor 19 and a capacitor 20 so as to cause during this resonance a suitable overvoltage.
  • T3 and T4 on the other hand are operated by an external circuit (not shown) so that some close when the others open.
  • incon there are still some problems, in particular the fact that the switching frequency must be exactly adjusted to the resonant frequency when the latter can drift during operation, making the lighting of the lamp uncertain, especially after accidental or voluntary shutdown. of it.
  • FIG. 4 finally illustrates another alternative embodiment also known in which only two transistors T ⁇ and T respectivement respectively, mounted in two branches of the point, are used for each alternation of the supply current, the other two branches comprising two decoupling capacitors 14a and 14b.
  • the operation is analogous and leads to the same drawbacks.
  • Figure 5 illustrates the adaptations made according to the invention to the mounting of a switching power supply of the kind illustrated in Figure 3.
  • the supply terminals 1 and 2 the filter 12 and the rectifier 13 of the mains supply voltage, the capacitor 14 and the terminals 15 and 16 on the one hand, 17 and 18 of the bridge, the latter comprising in its branches the four transistors T1 to T4 and in its diagonal the winding of inductor 19, capacity 20 and finally at terminals 21 and 22 of the latter, the arc lamp 23.
  • the closing or opening of the switches T1 to T4 is produced from pulses delivered on their gates and coming from a pulse generator circuit. 24, the details of an exemplary embodiment of which will be given below.
  • This generator in fact delivers on an output 25 pulses which are either directly routed to the gates of the transistors T1 and T3 by connections 26 and 27, either through a galvanic isolation transformer 28 and the secondary windings 29 and 30 thereof to the gates of the transistors T2 and T4, according to the alternations of the supply current in order to store the energy in the self 19 necessary for the creation of the lighting overvoltage of the lamp 23.
  • FIG. 6 now illustrates in more detail the construction of this pulse generator 24.
  • This circuit 33 is associated with a resistor 34 and a capacitor 35, adjusted so that, without further action and in particular when the lamp is on, it supplies at its output voltage pulses having a base or reference frequency, by example equal to 70 kHz and in any event lower than the resonance frequency of the circuit constituted by the inductor 19 and the capacitor 20 at the terminals of the lamp 23.
  • the current passing through a spindle 50 of the circuit 33 is varied in a sawtooth fashion from a variable so-called sweep voltage, supplied at 36 on the base of a transistor 37, the emitter of which is connected to a resistor bridge, respectively 38 and 39, the resistor 39 having for example a double value of the resistor 38.
  • the voltage at rest on the emitter of transistor 37 is equal to 1/3 of the supply voltage.
  • the output current supplied to pin 50 by connection 40 which in a way constitutes the image of the scanning voltage at 36 minus the reference voltage on the emitter of transistor 37, will vary between two values which correspond to a zero value and a maximum value successively according to respectively increasing and decreasing laws, and with a predetermined scanning period, dependent on that of the corresponding voltage signal.
  • the diagram of FIG. 7 illustrates, for a given scanning period, fixed by a circuit 48 and the role of which will be specified below, chosen for example here of the order of one second, the shape of the signal representative of the voltage of scan in 36, thus gradually increasing then decreasing.
  • the circuit 33 then realizes from this voltage sweep, a concomitant variation of the frequency of the output pulses delivered on the output 25, within a determined range and which surrounds the resonance frequency of the circuit of the choke 19 or one of its harmonics and of the capacitor 20.
  • the frequency thus varies between 70 kHz and 160 kHz, so as to necessarily intersect the resonance frequency, chosen by construction equal to approximately 100 kHz for example.
  • the pulse generator 24 is designed in such a way that simultaneously with the frequency sweeping of the pulses supplied, they have a crossing angle, that is to say a ratio of their duration to their period which remains substantially constant during the scanning of the range, therefore whatever the frequency of these pulses.
  • the circuit 33 has an input 41 for an adjustment voltage delivered from a bridge of two resistance 42 and 43, at the terminals of which a third resistance 44 is connected, the variable current passing through this resistance 44, coming from a transistor 45 making it possible to vary in proportion to the frequency of the pulses therefore to their period , the duration of these.
  • the passage angle is maximum; if, on the other hand, the transistor 45 is conductive and flows through the resistor 44, the passage angle is minimal, in correspondence with the equally maximum and minimum values of the chopping frequency in the range considered, as shown in Figure 7 in the diagram thereof giving the shape of the pulses at the output of circuit 33, on connection 25.
  • the pulse generator 24 also comprises a circuit 46, connected to the complementary winding 31 detecting the passage of current at the output of the lamp 23, if once the latter is turned on, this circuit 46 making it possible to immediately bring to zero the output voltage of this circuit at point 47, thereby blocking transistor 45 and consequently restoring the angle of passage of the pulses supplied by circuit 33 to a maximum and optimal value, defined by the ratio of resistors 42 and 43, the resistor 44 no longer intervening.
  • the voltage thus brought to zero at 47 then acts on a complementary circuit 48, itself supplying a signal making it possible to inhibit the transistor 37 so that the voltage at 36 and consequently the chopping frequency of the final signal for controlling the transistors T1 to T4 is necessarily reduced to a value lower than the resonance frequency.
  • the circuit 48 is a RESET 555 type circuit, manufactured in particular by the same companies as mentioned above.
  • the pulses from the generator 24, delivered by the circuit 33 on the connection 25 are routed after suitable amplification if necessary in 49 to the winding 28 of the transformer and either directly to the connections 26 and 27 joined to the gates of the transistors T1 and T3, or through the windings 29 and 30 to the gates of the other two transistors T2 and T4, thereby ensuring control of the alternating conduction and blocking sequences of these transistors, symmetrically and by identical pulses, in accordance with arrangements made or opened in a known manner in conventional devices of the series inverter type.
  • FIG. 7 then makes it possible to explain the particular operation of the pulse generator according to the invention, during the lighting phase of the lamp where the scanning voltage is gradually caused to increase and then decrease with a predetermined period to ensure a Adequate frequency sweep of the choke of the resonant circuit.
  • the pulses at the output of the generator 25 indeed have a variable frequency, chosen so that it scans permanently, with the periodicity thus predetermined, a range of 70 to 160 kHz for example, and that it therefore necessarily overlaps the resonant frequency of the self circuit 19- capacitor 20 or one of its harmonics, in series with the lamp 23.
  • the angle of passage of the pulses is kept constant by the resistors 42, 43 and 44 and limited to a reduced value , especially around 5%.
  • the diagram of FIG. 7 illustrates the profile of the pulses thus delivered on the connection 25 at the output of the generator 24, the duration of the pulses being all the more reduced that their frequency is greater and vice versa, the quantity of corresponding energy remaining in total identical to itself.
  • the self resistance circuit 19 - capacitor 20 enters into resonance and produces, at the terminals of the lamp 23, the necessary ignition overvoltage.
  • the lamp igniting it immediately delivers a current, detected and returned to the pulse generator 24 to the pulse generator 24.
  • This due to the zeroing of the voltage at point 47 stops the frequency scanning and reduces the effective frequency of the chopping pulses to a value lower than the resonant frequency.
  • the angle of passage of the pulses is then simultaneously increased to an optimal value, for example of the order of 45%.
  • the transistor 37 is blocked while the switching frequency is brought back to its reference value, determined by the resistor 34 and the capacitor 35.

Abstract

Process for igniting a discharge lamp, in particular of the arc-lamp or neon tube type, the said lamp being mounted in a series resonant circuit comprising a choke (19) and a capacitor (20), the lamp (23) being disposed in series with the choke and in parallel with the capacitor, this resonant circuit being disposed in the diagonal of a bridge to the terminals of which are supplied voltage pulses delivered by a chopped supply, characterised in that it consists in varying the chopping frequency of the energising pulses over a frequency range stretching between two predetermined extreme values which enclose the resonance frequency of the circuit or one of its harmonics in accordance with an approximately linear law, respectively increasing then decreasing, with a scanning period for this given range, in simultaneously setting to a constant and bounded value the angle of flow of the pulses measuring the ratio of the duration of the latter to their period, so that the current supplied to the lamp on each pulse is substantially reduced, in then igniting the lamp by virtue of the voltage surge created by the resonance of the circuit when the chopping frequency is equal to the resonance frequency or one of its harmonics, in detecting the flow of the current in the lamp in order to reduce the frequency of the pulses to a value substantially lower than the resonance frequency, at the same time the angle of flow being raised to an optimal value. <IMAGE>

Description

La présente invention est relative à un procédé et un dispositif d'allumage électronique, notamment destiné à l'alimentation de lampes à décharge, à cathode froide ou chaude, à partir du courant alternatif du secteur.The present invention relates to an electronic ignition method and device, in particular intended for supplying discharge lamps, with cold or hot cathode, from alternating current from the mains.

On sait que le principe de l'allumage d'une lampe à décharge du genre lampe à arc ou tube au néon, consiste à créer aux bornes de la lampe entre les électrodes de celle-ci, une surtension notable, propre à créer une ionisation du gaz emprisonné dans l'enceinte de la lampe et à établir entre les électrodes un arc électrique, formant en quelque sorte l'équivalent du filament électrique d'éclairage dans une lampe conventionelle. Or, une telle surtension résulte ordinairement de la mise en oeuvre d'un circuit self-capacité, amené à la résonance de telle sorte que, l'impédance du circuit s'annulant, la tension devienne maximale. Cependant, avec un courant d'alimentation alternatif à 50 périodes tel que fourni par le secteur, l'enroulement de la self du circuit résonnant doit être particulièrement important pour créer une surtension acceptable. Il en rüsulte un coût élevé des installations avec de plus dans ce cas un facteur de charge ou cosinus de l'installation particulièrement médiocre, conduisant à un échauffement parasite inacceptable. Enfin, le circuit et en particulier la self présente un encombrement notable, qui pose des problèmes de poids pour l'allumage de lampes à arc d'usage courant.We know that the principle of lighting a discharge lamp of the arc lamp or neon tube type, consists in creating at the terminals of the lamp between the electrodes thereof, a notable overvoltage, capable of creating an ionization. gas trapped in the lamp enclosure and to establish an electric arc between the electrodes, forming in a way the equivalent of the electric lighting filament in a conventional lamp. However, such an overvoltage usually results from the use of a self-capacitance circuit, brought to resonance so that, the impedance of the circuit canceling out, the voltage becomes maximum. However, with an alternating supply current at 50 periods as supplied by the sector, the winding of the resonant of the resonant circuit must be particularly important to create an acceptable overvoltage. This results in a high cost of the installations with, in this case, in addition a particularly poor load factor or cosine of the installation, leading to unacceptable parasitic heating. Finally, the circuit and in particular the inductor presents a considerable bulk, which poses weight problems for the lighting of arc lamps in common use.

On a donc déjà envisagé pour pallier ces inconvé­nient, d'accroître la fréquence du courant passant dans la self du circuit résonnant, notamment à l'aide d'une alimentation dite à découpage, qui fractionne le courant alternatif sinusoïdal à 50 périodes du secteur, le cas échéant préalablement filtré et redressé, en impulsions de faible période donc de fréquence plus élevée, par exemple de l'ordre de 70 kHz. Dans une telle alimentation, le courant alternatif redressé et filtré est découpé en impulsions successives de fréquence notable par des inter­rupteurs électroniques, notamment constituées par des transistors alternativement conducteurs et bloqués, dispo­sés en pont et qui comporte dans la diagonale de celui-ci, le circuit résonnant, la self étant montée en série avec la lampe à arc dont on désire provoquer l'allumage, la capacité étant connectée en parallèle sur les électrodes de la lampe. Celle-ci constitue ainsi un circuit ouvert avant l'établissement de l'arc électrique et un circuit présentant une faible impédance une fois l'arc établi.To overcome these drawbacks, it has therefore already been envisaged to increase the frequency of the current passing through the choke of the resonant circuit, in particular using a so-called switching power supply, which splits the current sinusoidal AC with 50 periods from the mains, if necessary previously filtered and rectified, in pulses of low period therefore of higher frequency, for example of the order of 70 kHz. In such a supply, the rectified and filtered alternating current is cut into successive pulses of notable frequency by electronic switches, in particular constituted by alternately conductive and blocked transistors, arranged in a bridge and which comprises in the diagonal thereof, the circuit resonant, the inductor being mounted in series with the arc lamp which it is desired to cause the ignition, the capacitor being connected in parallel on the electrodes of the lamp. This thus constitutes an open circuit before the establishment of the electric arc and a circuit having a low impedance once the arc is established.

Mais dans une installation de ce genre, dans laquelle les transistors constituant les interrupteurs du pont doivent être manoeuvrés très précisément en synchro­nisme deux à deux, de telle sorte que les uns se ferment lorsque les autres s'ouvrent, l'intensité qui traverse le circuit à la résonance devient lors de l'établissement de la surtension d'allumage particulièrement élevée puisque l'impédance s'annule, ce qui exige des protections pour limiter cette surintensité et éviter la détérioration immédiate de l'installation. A cet effet, on prévoît de réduire la durée des impulsions de tension fournies au pont, en ajustant ce que l'on appelle l'angle de passage de ces impulsions, cet angle étant égal au rapport de la durée des impulsions à leur période. Dans ces conditions, si l'angle de passage est convenablement limité, la quantité d'énergie électrique traversant le circuit sera plus faible, ce qui atténue les conséquences de la surintensité créée à la résonance.But in an installation of this kind, in which the transistors constituting the switches of the bridge must be operated very precisely in synchronism two by two, so that some close when the others open, the intensity which crosses the circuit at the resonance becomes during the establishment of the particularly high ignition overvoltage since the impedance is canceled, which requires protections to limit this overcurrent and avoid the immediate deterioration of the installation. To this end, provision is made to reduce the duration of the voltage pulses supplied to the bridge, by adjusting what is called the angle of passage of these pulses, this angle being equal to the ratio of the duration of the pulses to their period. Under these conditions, if the angle of passage is suitably limited, the amount of electrical energy passing through the circuit will be lower, which mitigates the consequences of the overcurrent created at resonance.

Toutefois, de telles alimentations à découpage présentent encore des inconvénients. Notamment, elles sont généralement complexes et surtout posent des problèmes pour générer la tension d'allumage nécessaire après coupure accidentelle ou volontaire de l'arc entre les électrodes de la lampe, celle-ci ne pouvant s'allumer à nouveau qu'après un temps de refroidissement suffisant. De plus, ces alimentations à haute fréquence créent des parasites dans leur environnement. Enfin, l'inconvénient le plus grave de ce genre d'alimentations est que la fréquence de découpage de la tension d'entrée filtrée et redressée, doit être ajustée exactement sur la fréquence de résonance du circuit self-capacité qui est elle-même imprécise en raison d'une dispersion de la self et de la capacité en fonctionnement, et également d'une dispersion complémentaire due aux capacités parasites créées par la lampe elle-même et le cablage du montage.However, such switching power supplies still have drawbacks. In particular, they are generally complex and above all pose problems for generating the necessary ignition voltage after accidental or voluntary interruption of the arc between the electrodes of the lamp, the latter being able to ignite again only after a sufficient cooling time. In addition, these high frequency power supplies create parasites in their environment. Finally, the most serious drawback of this kind of power supply is that the chopping frequency of the filtered and rectified input voltage must be adjusted exactly to the resonant frequency of the self-capacitance circuit which is itself imprecise. due to a dispersion of the choke and the capacity in operation, and also of a complementary dispersion due to the parasitic capacities created by the lamp itself and the wiring of the assembly.

La présente invention concerne un procédé et un dispositif qui, tout en conservant le principe de l'allu­mage de la lampe à arc, grâce à la surtension créée dans un circuit résonnant, au moyen d'une alimentation à décou­page fournissant des impulsions de fréquence élevée, permet d'utiliser en enroulement de self dont la valeur peut être relativement imprécise et évite les inconvé­nients des solutions classiques, en procurant par ailleurs une grande sécurité de fonctionnement, notamment sans risque de surintensité dans le circuit de la lampe lors de son allumage. L'invention a également pour but d'assurer, en cas de coupure de l'alimentation de la lampe, un réallumage sûr de celle-ci.The present invention relates to a method and a device which, while retaining the principle of lighting the arc lamp, by virtue of the overvoltage created in a resonant circuit, by means of a switching power supply providing pulses of high frequency , allows the use of inductor windings, the value of which can be relatively imprecise and avoids the drawbacks of conventional solutions, while also providing great operational safety, in particular without the risk of overcurrent in the lamp circuit when it is switched on. The object of the invention is also to ensure, in the event of a cut in the supply of the lamp, a safe re-ignition thereof.

A cet effet, le procédé considéré, pour l'allumage d'une lampe à décharge montée dans un circuit résonant série comportant une self et une capacité, la lampe étant disposée en série avec la self et en parallèle sur la capacité, ce circuit résonnant étant disposé dans la diagonale d'un pont aux bornes duquel sont fournies des impulsions de tension délivrées par une alimentation à découpage, se caractérise en ce qu'il consiste à faire varier la fréquence de découpage des impulsions d'alimen­tation dans une plage de fréquences s'étendant entre deux valeurs extrêmes prédéterminées qui entourent la fréquence de résonance du circuit ou une de ses harmoniques selon une loi approximativement linéaire, respectivement crois­sante puis décroissante, avec une période de balayage donnée de cette plage, à ajuster l'angle de passage des impulsions mesurant le rapport de la durée de celles-ci à leur période à une valeur constante et limitée de telle sorte que le courant fourni à la lampe à chaque impulsion soit sensiblement réduit, puis à l'allumage de la lampe grâce à la surtension créée par la résonance du circuit lorsque la fréquence de découpage est égale à la fréquence de résonance, à détecter le passage du courant dans la lampe pour ramener la fréquence des impulsions à un valeur notablement inférieure à la fréquence de résonance , l'angle de passage étant en même temps augmenté à une valeur optimale.To this end, the process considered, for the ignition of a discharge lamp mounted in a series resonant circuit comprising an inductor and a capacitor, the lamp being arranged in series with the inductor and in parallel on the capacitor, this resonant circuit being placed in the diagonal of a bridge at the terminals of which are supplied voltage pulses supplied by a power supply switching, is characterized in that it consists in varying the switching frequency of the supply pulses in a frequency range extending between two predetermined extreme values which surround the resonant frequency of the circuit or one of its harmonics according to a approximately linear law, respectively increasing then decreasing, with a given scanning period of this range, to adjust the angle of passage of the pulses measuring the ratio of the duration of these to their period to a constant and limited value so that that the current supplied to the lamp at each pulse is significantly reduced, then when the lamp is turned on thanks to the overvoltage created by the resonance of the circuit when the switching frequency is equal to the resonance frequency, to detect the passage of the current in the lamp to reduce the frequency of the pulses to a value significantly lower than the resonance frequency, the angle of passage being at the same time a increased to an optimal value.

Le procédé selon l'invention permet ainsi, lors de chaque séquence d'allumage de la lampe, de faire en sorte que la fréquence de découpage ou l'un de ses harmoniques varie régulièrement entre une fréquence minimale inférieure à la fréquence de résonance, et une fréquence maximale supérieure à cette fréquence de résonance, l'angle de passage des impulsions, caractérisant la quantité d'énergie électrique traversant les interrupteurs électroniques alimentant la lampe selon les alternances du courant d'alimentation, étant réduit à une valeur telle qu'à l'allumage la surintensité produite soit toujours acceptable par l'installation. Il en résulte lors du balayage en fréquence, un passage obligatoire de celle-ci à la valeur correspondant à la résonance du circuit self-­capacité associé à la lampe, provoquant son allumage, sans pour autant nécessiter aucun ajustage des composants constituant ce circuit en cours de fabrication ou en cours d'utilisation.The method according to the invention thus makes it possible, during each ignition sequence of the lamp, to ensure that the switching frequency or one of its harmonics varies regularly between a minimum frequency lower than the resonance frequency, and a maximum frequency greater than this resonant frequency, the angle of passage of the pulses, characterizing the amount of electrical energy passing through the electronic switches supplying the lamp according to the alternations of the supply current, being reduced to a value such that at ignition the overcurrent produced is always acceptable by the installation. This results in frequency sweeping, a compulsory passage from the latter to the value corresponding to the resonance of the self-capacitance circuit associated with the lamp, causing it to light up, without requiring any adjustment of the components. constituting this circuit during manufacture or during use.

L'invention concerne également un dispositif pour la mise en oeuvre du procédé, comportant une alimentation à découpage constituée d'une source de tension filtrée et redressée, réunie aux bornes d'un pont comportant dans chacune de ses branches des interrupteurs électroniques deux à deux associés et dans la diagonale du pont, un circuit résonnant comportant un enroulement de self et une capacité, la lampe étant montée dans cette diagonale en série avec la self et en parallèle sur la capacité, les interrupteurs étant manoeuvrés simultanément de telle sorte que les uns se ferment lorsque les autres s'ouvrent, caractérisé en ce que l'alimentation à découpage comporte un générateur d'impulsions agencé de telle sorte que les impulsions aux bornes du pont présentent une fréquence variable respectivement croissante puis décroissante, en balayant une plage de fréquences s'étendant entre une valeur inférieure et une valeur supérieure à la fréquence de résonance du circuit ou une de ses harmoniques et dont l'angle de passage est faible, de telle façon qu'à la résonance le courant qui traverse la lampe et les interrupteurs soit limité à une valeur admissible, et en ce qu'il comporte en série avec la lampe, un organe détec­teur du passage du courant dans cette lampe lors de son allumage de façon telle que le balayage en fréquence soit instantanément supprimé, la tension aux bornes du pont étant ramenée à une fréquence inférieure à la fréquence de résonance tandis que l'angle de passage est augmenté jusqu'à une valeur optimale.The invention also relates to a device for implementing the method, comprising a switching power supply consisting of a filtered and rectified voltage source, joined to the terminals of a bridge comprising in each of its branches electronic switches in pairs associated and in the diagonal of the bridge, a resonant circuit comprising a winding of inductor and a capacitor, the lamp being mounted in this diagonal in series with the inductor and in parallel on the capacitor, the switches being operated simultaneously so that each close when the others open, characterized in that the switching power supply includes a pulse generator arranged so that the pulses at the terminals of the bridge have a variable frequency which increases and decreases respectively, by scanning a range of frequencies extending between a lower value and a higher value at the resonant frequency of the circuit or one of its harmonics ues and whose angle of passage is small, so that at resonance the current passing through the lamp and the switches is limited to an admissible value, and in that it comprises in series with the lamp, a member detector of the passage of current in this lamp when it is switched on so that the frequency sweep is instantly suppressed, the voltage at the terminals of the bridge being reduced to a frequency lower than the resonant frequency while the passage angle is increased up to an optimal value.

Selon une caractéristique particulière, les interrupteurs électroniques sont constitués par des transistors MOS recevant sur leur grille des impulsions de tension provenant du générateur et provoquant la conduction ou le blocage alterné de ces transistors. De préférence, les impulsions de tension sont fournies à travers les enroulements d'un transformateur d'isolement.According to a particular characteristic, the electronic switches consist of MOS transistors receiving on their grid voltage pulses coming from the generator and causing the alternating conduction or blocking of these transistors. Of preferably, the voltage pulses are supplied through the windings of an isolation transformer.

Selon une caractéristique particulière du dispositif de l'invention, le générateur d'impulsions comprend un circuit fournissant un signal en dents de scie dont l'amplitude et la période varient entre deux valeurs de coupure prédéterminées, des moyens pour produire à partir de ce signal une variation de la fréquence de découpage respectivement croissante puis décroissante et des moyens pour ajuster simultanément la période et la durée des impulsions de tension fournies selon la variation de la fréquence de découpage à un angle de passage présentant une valeur constante à travers toute la plage.According to a particular characteristic of the device of the invention, the pulse generator comprises a circuit supplying a sawtooth signal whose amplitude and period vary between two predetermined cutoff values, means for producing from this signal a variation in the switching frequency respectively increasing then decreasing and means for simultaneously adjusting the period and the duration of the voltage pulses supplied according to the variation in the switching frequency at a passage angle having a constant value across the whole range.

Selon une autre caractéristique de l'invention, le détecteur du courant d'allumage dans la lampe est constitué par un enroulement de self complémentaire, disposé sur un conducteur réuni à une des électrodes de la lampe et dans lequel le passage du courant après l'allumage crée un signal de tension tel que la variation du courant ainsi détectée agisse sur le générateur d'impulsions et ramène la fréquence de découpage à sa valeur inférieure dans la plage, où elle est inférieure à la fréquence de résonance, l'angle de passage des impulsions étant ramené simultanément à une valeur plus élevée.According to another characteristic of the invention, the detector of the ignition current in the lamp is constituted by a complementary inductor winding, arranged on a conductor joined to one of the electrodes of the lamp and in which the passage of the current after the ignition creates a voltage signal such that the variation in current thus detected acts on the pulse generator and reduces the switching frequency to its lower value in the range, where it is less than the resonance frequency, the angle of passage pulses being reduced simultaneously to a higher value.

D'autres caractéristiques du procédé et du dispositif pour l'allumage d'une lampe à décharge au moyen d'une alimentation à découpage établie conformément à l'invention apparaîtront encore à travers la description qui suit d'un exemple de réalisation, donné à titre indicatif et non limitatif, en référence aux dessins annexés sur lesquels :

  • - Les Figures 1 et 2 sont des vues schématiques de dispositifs connus dans la technique, permettant de réaliser l'allumage d'une lampe à arc, respectivement à cathode froide et à cathode chaude.
  • - Les Figures 3 et 4 illustrent d'autres dispositifs également connus dans la technique pour assurer l'allumage d'une lampe à arc, au moyen d'une alimentation à découpage.
  • - La Figure 5 est un schéma de principe montrant l'adaptation d'un des circuits précédents, conformément aux dispositions de l'invention.
  • - La Figure 6 est une vue de détail du générateur d'impulsions mis en oeuvre dans le montage de la Figure 5.
  • - La Figure 7 est un diagramme donnant la variation de la tension en divers points du montage selon les Figures 5 et 6.
Other characteristics of the method and of the device for lighting a discharge lamp by means of a switching power supply established in accordance with the invention will become more apparent from the following description of an exemplary embodiment, given at indicative and non-limiting, with reference to the accompanying drawings in which:
  • - Figures 1 and 2 are schematic views of devices known in the art, for switch on an arc lamp, with a cold cathode and a hot cathode respectively.
  • - Figures 3 and 4 illustrate other devices also known in the art for ensuring the ignition of an arc lamp, by means of a switching power supply.
  • - Figure 5 is a block diagram showing the adaptation of one of the preceding circuits, in accordance with the provisions of the invention.
  • - Figure 6 is a detailed view of the pulse generator used in the assembly of Figure 5.
  • - Figure 7 is a diagram giving the variation of the voltage at various points of the assembly according to Figures 5 and 6.

Dans l'exemple représenté sur la Figure 1, les références 1 et 2 désignent les bornes d'une source de tension alternative connectée à un circuit d'allumage comportant une capacité 3 et un enroulement de self 4, respectivement réunis aux électrodes 5 et 6 d'une lampe à décharge 7 à cathode froide. Entre les électrodes 5 et 6, le circuit comporte un générateur de surtension 8, permet­tant de créer entre ces électrodes une tension d'allumage très élevée telle que s'établisse dans la lampe un arc électrique. En fonctionnement, si la tension entre les électrodes 5 et 6 est de l'ordre de 100 volts, le généra­teur de surtension 8 doit être capable de créer à l'allumage une tension de l'ordre du millier de volts au moins.In the example shown in Figure 1, references 1 and 2 designate the terminals of an alternating voltage source connected to an ignition circuit comprising a capacity 3 and a winding of inductor 4, respectively joined to electrodes 5 and 6 a discharge lamp 7 with a cold cathode. Between the electrodes 5 and 6, the circuit includes an overvoltage generator 8, making it possible to create between these electrodes a very high ignition voltage such that an electric arc is established in the lamp. In operation, if the voltage between the electrodes 5 and 6 is of the order of 100 volts, the overvoltage generator 8 must be capable of creating a ignition voltage of the order of a thousand volts at least.

Dans l'exemple selon la Figure 2, la lampe 7 est une lampe à cathode chaude où les électrodes 9 et 10 sont, préalablement à l'allumage, parcourues par un courant élevant leur température, suite à la fermeture d'un inter­rupteur 11 appelé communément "starter" monté en parallèle et plaçant ces électrodes en court-circuit. Dans cette variante, pour une tension de fonctionnement également de l'ordre de quelques centaines de volts, la tension d'allumage est encore de l'ordre de 400 volts.In the example according to FIG. 2, the lamp 7 is a hot cathode lamp where the electrodes 9 and 10 are, prior to ignition, traversed by a current raising their temperature, following the closing of a switch 11 called commonly "choke" mounted in parallel and placing these electrodes in short circuit. In this variant, for an operating voltage also of around a few hundred volts, the ignition voltage is still around 400 volts.

Dans l'un ou l'autre des cas précédents, l'enroulement de self 4 doit permettre lors de la mise en court-circuit des électrodes de la lampe de fournir à celle-ci une surtension convenable propre à créer l'arc entre les électrodes. Or, en raison de la fréquence du courant d'alimentation, ordinairement du courant alterna­tif à 50 périodes, cette self doit présenter des dimen­sions importantes, ce qui entraîne dans tous les cas un encombrement et un poids élevé, mal adapté en particulier à un usage pour des lampes à décharge ou des tubes au néon à utilisation domestique ou même industrielles.In either of the preceding cases, the winding of the inductor 4 must make it possible, when the electrodes of the lamp are short-circuited, to supply the latter with a suitable overvoltage capable of creating the arc between the electrodes. However, due to the frequency of the supply current, usually alternating current at 50 periods, this inductor must have large dimensions, which in all cases results in a bulk and a high weight, ill-suited in particular for use. for discharge lamps or neon tubes for domestic or even industrial use.

Les Figures 3 et 4 illustrent des systèmes d'allumage également connus dans la technique mais à fonctionnement électronique. La source de tension alternative à 50 périodes du secteur est réunie aux bornes 1 et 2 du circuit, cette tension étant ensuite filtrée en 12 puis redressée en 13 de manière à fournir aux bornes 15 et 16 d'un condensateur 14 à l'entrée d'un circuit de découpage une tension continue redressée appropriée. Entre les bornes 17 et 18 de la diagonale d'un pont de transistors, respectivement repérés T1 à T4, est disposé un circuit résonnant, comportant un enroulement de self 19 et une capacité 20. La lampe à décharge 23 est disposée aux bornes 21 et 22 de cette dernière.Figures 3 and 4 illustrate ignition systems also known in the art but with electronic operation. The AC voltage source at 50 periods from the sector is connected to terminals 1 and 2 of the circuit, this voltage then being filtered at 12 and then rectified at 13 so as to supply terminals 15 and 16 of a capacitor 14 at the input d 'an appropriate rectified DC voltage cutting circuit. Between the terminals 17 and 18 of the diagonal of a bridge of transistors, respectively marked T1 to T4, is arranged a resonant circuit, comprising a winding of inductor 19 and a capacitor 20. The discharge lamp 23 is arranged at the terminals 21 and 22 of the latter.

La tension d'allumage à créer à ces bornes 21 et 22 est obenue par mise en résonance d'un circuit série constitué par un enroulement de self 19 et une capacité 20 de manière à provoquer lors de cette résonance une surten­sion convenable. Dans ce cas, les interrupteurs respecti­vement T1 et T2 d'une part. T3 et T4 d'autre part, sont manoeuvrés par un circuit extérieur (non représenté) de telle sorte que les uns se ferment lorsque les autres s'ouvrent. Toutefois, dans une telle solution, des incon­ vénients subsistent, en particulier du fait que la fréquence de découpage doit être exactement ajustée sur la fréquence de résonance alors que celle-ci peut dériver en cours de fonctionnement, rendant dès lors l'allumage de la lampe incertain, surtout après coupure accidentelle ou volontaire de celle-ci.The ignition voltage to be created at these terminals 21 and 22 is obtained by resonance of a series circuit constituted by a winding of inductor 19 and a capacitor 20 so as to cause during this resonance a suitable overvoltage. In this case, the switches respectively T1 and T2 on the one hand. T3 and T4 on the other hand, are operated by an external circuit (not shown) so that some close when the others open. However, in such a solution, incon There are still some problems, in particular the fact that the switching frequency must be exactly adjusted to the resonant frequency when the latter can drift during operation, making the lighting of the lamp uncertain, especially after accidental or voluntary shutdown. of it.

La Figure 4 illustre enfin une autre variante de réalisation également connue où l'on utilise seulement pour chaque alternance du courant d'alimentation deux transistors respectivement Tʹ et Tʺ, montés dans deux branches du point, les deux autres branches comportant deux condensateurs de découplage 14a et 14b. Dans ce cas cependant, le fonctionnement est analogue et conduit aux mêmes inconvénients.FIG. 4 finally illustrates another alternative embodiment also known in which only two transistors Tʹ and T respectivement respectively, mounted in two branches of the point, are used for each alternation of the supply current, the other two branches comprising two decoupling capacitors 14a and 14b. In this case, however, the operation is analogous and leads to the same drawbacks.

La Figure 5 illustre les adaptations apportées conformément à l'invention au montage d'une alimentation à découpage du genre de celle illustrée sur la Figure 3. On retrouve sur cette Figure, les bornes d'alimentation 1 et 2, le filtre 12 et le redresseur 13 de la tension d'alimentation du secteur, le condensateur 14 et les bornes 15 et 16 d'une part, 17 et 18 du pont, celui-ci comportant dans ses branches les quatre transistors T1 à T4 et dans sa diagonale l'enroulement de self 19, la capacité 20 et enfin aux bornes 21 et 22 de cette dernière, la lampe à arc 23.Figure 5 illustrates the adaptations made according to the invention to the mounting of a switching power supply of the kind illustrated in Figure 3. In this Figure, we find the supply terminals 1 and 2, the filter 12 and the rectifier 13 of the mains supply voltage, the capacitor 14 and the terminals 15 and 16 on the one hand, 17 and 18 of the bridge, the latter comprising in its branches the four transistors T1 to T4 and in its diagonal the winding of inductor 19, capacity 20 and finally at terminals 21 and 22 of the latter, the arc lamp 23.

La fermeture ou l'ouvertures des interrupteurs T1 à T4, de préférence constitués par des transistors MOS qui selon leur état sont respectivement conducteurs ou blo­qués, est réalisé à partir d'impulsions délivrées sur leurs grilles et provenant d'un circuit générateur d'impulsions 24 dont le détail d'un exemple de réalisation sera donné plus loin.The closing or opening of the switches T1 to T4, preferably constituted by MOS transistors which, depending on their state, are respectively conductive or blocked, is produced from pulses delivered on their gates and coming from a pulse generator circuit. 24, the details of an exemplary embodiment of which will be given below.

Ce générateur délivre en effet sur une sortie 25 des impulsions qui sont, soit directement acheminées aux grilles des transistors T1 et T3 par des connexions 26 et 27, soit à travers un transformateur d'isolement galvanique 28 et les enroulements secondaires 29 et 30 de celui-ci aux grilles des transistors T2 et T4, suivant les alternances du courant d'alimentation afin d'emmagasiner dans la self 19 l'énergie nécessaire à la création de la surtension d'allumage de la lampe 23. Enfin, sur la sortie de celle-ci est prévu un enroulement détecteur 31, constitué par un petit enroulement de self complémentaire, propre à détecter le passage du courant dans la lampe une fois celle-ci allumée, en fournissant par un conducteur 32 une impulsion de commande au générateur 24.This generator in fact delivers on an output 25 pulses which are either directly routed to the gates of the transistors T1 and T3 by connections 26 and 27, either through a galvanic isolation transformer 28 and the secondary windings 29 and 30 thereof to the gates of the transistors T2 and T4, according to the alternations of the supply current in order to store the energy in the self 19 necessary for the creation of the lighting overvoltage of the lamp 23. Finally, on the output of the latter is provided a detector winding 31, constituted by a small complementary winding of self, suitable for detecting the passage of current in the lamp once it is on, by supplying a control pulse to the generator 24 via a conductor 32.

La figure 6 illustre maintenant plus en détail la réalisation de ce générateur d'impulsions 24.FIG. 6 now illustrates in more detail the construction of this pulse generator 24.

Celui-ci comporte essentiellement un circuit 33 d'un type en lui-même connu, par exemple tel que celui commercialisé notamment par les Sociétés TEXAS INSTRUMENTS et SIGNETICS, sous la référence SG 3524, fournissant sur le conducteur de sortie 25 les impulsions de commande des transistors T1 et T4. Ce circuit 33 est associé à une résistance 34 et une capacité 35, ajustées de telle sorte que, sans autre invervention et notamment lorsque la lampe est allumée, il fournisse à sa sortie des impulsions de tension présentant une fréquence de base ou de référence, par exemple égale à 70kHz et en tout état de cause inférieure à la fréquence de résonance du circuit constitué par la self 19 et la capacité 20 aux bornes de la lampe 23.This essentially comprises a circuit 33 of a type known per se, for example such as that sold in particular by the companies TEXAS INSTRUMENTS and SIGNETICS, under the reference SG 3524, supplying the control pulses on the output conductor 25 transistors T1 and T4. This circuit 33 is associated with a resistor 34 and a capacitor 35, adjusted so that, without further action and in particular when the lamp is on, it supplies at its output voltage pulses having a base or reference frequency, by example equal to 70 kHz and in any event lower than the resonance frequency of the circuit constituted by the inductor 19 and the capacitor 20 at the terminals of the lamp 23.

Pour modifier la fréquence ci-dessus et réaliser selon l'invention le balayage en fréquence prévu, on fait varier en dents de scie le courant traversant une broche 50 du circuit 33 à partir d'une tension variable dite de balayage, fournie en 36 sur la base d'un transistor 37 dont l'émetteur est réuni à un pont de résistances, respectivement 38 et 39, la résistance 39 présentant par exemple une valeur double de la résistance 38. En d'autres termes la tension au repos sur l'émetteur du transistor 37 est égale à 1/3 de la tension d'alimentation. Dans ces conditions, le courant de sortie amené à la broche 50 par la connexion 40, qui constitue en quelque sorte l'image de la tension de balayage en 36 diminué de la tension de référence sur l'émetteur du transistor 37, va varier entre deux valeurs qui correspondent à une valeur nulle et une valeur maximale successivement selon des lois respective­ment croissante et décroissante, et avec une période de balayage prédéterminée, dépendant de celle du signal de tension correspondant.To modify the above frequency and carry out the planned frequency sweep according to the invention, the current passing through a spindle 50 of the circuit 33 is varied in a sawtooth fashion from a variable so-called sweep voltage, supplied at 36 on the base of a transistor 37, the emitter of which is connected to a resistor bridge, respectively 38 and 39, the resistor 39 having for example a double value of the resistor 38. In others terms the voltage at rest on the emitter of transistor 37 is equal to 1/3 of the supply voltage. Under these conditions, the output current supplied to pin 50 by connection 40, which in a way constitutes the image of the scanning voltage at 36 minus the reference voltage on the emitter of transistor 37, will vary between two values which correspond to a zero value and a maximum value successively according to respectively increasing and decreasing laws, and with a predetermined scanning period, dependent on that of the corresponding voltage signal.

Le diagramme de la Figure 7 illustre, pour une période de balayage donnée, fixée par un circuit 48 et dont le rôle sera précisé plus loin, choisie par exemple ici de l'ordre de une seconde, la forme du signal représentatif de la tension de balayage en 36, ainsi progressivement croissante puis décroissante. Le circuit 33 réalise alors à partir de ce balayage en tension, une variation concomitante de la fréquence des impulsions de sortie délivrée sur la sortie 25, dans une plage déterminée et qui entoure la fréquence de résonance du circuit de la self 19 ou une de ses harmoniques et du condensateur 20. Par exemple, dans la plage considérée, la fréquence varie ainsi entre 70 kHz et 160 kHz, de manière à recouper nécessairement la fréquence de résonance, choisie par construction égale à environ 100 kHz par exemple.The diagram of FIG. 7 illustrates, for a given scanning period, fixed by a circuit 48 and the role of which will be specified below, chosen for example here of the order of one second, the shape of the signal representative of the voltage of scan in 36, thus gradually increasing then decreasing. The circuit 33 then realizes from this voltage sweep, a concomitant variation of the frequency of the output pulses delivered on the output 25, within a determined range and which surrounds the resonance frequency of the circuit of the choke 19 or one of its harmonics and of the capacitor 20. For example, in the considered range, the frequency thus varies between 70 kHz and 160 kHz, so as to necessarily intersect the resonance frequency, chosen by construction equal to approximately 100 kHz for example.

Selon l'invention, le générateur d'impulsions 24 est conçu de telle manière que simultanément au balayage en fréquence des impulsions fournies, celles-ci présentent un angle de passage, c'est-à-dire un rapport de leur durée à leur période qui reste sensiblement constant au cours du balayage de la plage quelle que soit donc la fréquence de ces impulsions. A cet effet, le circuit 33 comporte une entrée 41 pour une tension de réglage délivrée à partir d'un pont de deux résistance 42 et 43, aux bornes desquelles est connectée une troisième résistance 44, le courant variable passant dans cette résistance 44, provenant d'un transistor 45 permettant de faire varier proportionnellement à la fréquence des impulsions donc à leur période, la durée de ces dernières. Si le transistor 45 est bloqué, l'angle de passage est maximum ; si, en revanche, le transistor 45 est conducteur et débite dans la résistance 44, l'angle de passage est minimal, en correspondance avec les valeurs également maximale et minimale de la fréquence de découpage dans la plage considérée, comme le réprésente la Figure 7 dans le diagramme de celle-ci donnant la forme des impulsions à la sortie du circuit 33, sur la connexion 25.According to the invention, the pulse generator 24 is designed in such a way that simultaneously with the frequency sweeping of the pulses supplied, they have a crossing angle, that is to say a ratio of their duration to their period which remains substantially constant during the scanning of the range, therefore whatever the frequency of these pulses. To this end, the circuit 33 has an input 41 for an adjustment voltage delivered from a bridge of two resistance 42 and 43, at the terminals of which a third resistance 44 is connected, the variable current passing through this resistance 44, coming from a transistor 45 making it possible to vary in proportion to the frequency of the pulses therefore to their period , the duration of these. If the transistor 45 is blocked, the passage angle is maximum; if, on the other hand, the transistor 45 is conductive and flows through the resistor 44, the passage angle is minimal, in correspondence with the equally maximum and minimum values of the chopping frequency in the range considered, as shown in Figure 7 in the diagram thereof giving the shape of the pulses at the output of circuit 33, on connection 25.

Le générateur d'impulsions 24 comporte par ailleurs un circuit 46, connecté à l'enroulement complémentaire 31 détectant le passage du courant à la sortie de la lampe 23, si une fois celle-ci allumée, ce circuit 46 permettant d'amener immédiatement à zéro la tension de sortie de ce circuit au point 47, en bloquant dès lors le transistor 45 et en restaurant par conséquent l'angle de passage des impulsions fournies par le circuit 33 à une valeur maximale et optimale, définie par le rapport des résistances 42 et 43, la résistance 44 n'intervenant plus. La tension ainsi amenée à zéro en 47 agit alors sur un circuit complémentaire 48, fournissant lui-même un signal permettant d'inhiber le transistor 37 de telle sorte que la tension en 36 et par suite la fré­quence de découpage du signal final de pilotage des tran­sistors T1 à T4 soit nécessairement ramenée à une valeur inférieure à la fréquence de résonance. Cet état se main­tient jusqu'à ce que la lampe soit à nouveau arrêtée accidentellement ou volontairement puis rallumée, auquel cas le balayage en fréquence recommence pour permettre une nouvelle résonance et une réinitialisation de l'arc de la lampe. Avantageusement, le circuit 48 est un circuit de type RESET 555, fabriqué notamment par les mêmes Sociétés que mentionnées précédemment.The pulse generator 24 also comprises a circuit 46, connected to the complementary winding 31 detecting the passage of current at the output of the lamp 23, if once the latter is turned on, this circuit 46 making it possible to immediately bring to zero the output voltage of this circuit at point 47, thereby blocking transistor 45 and consequently restoring the angle of passage of the pulses supplied by circuit 33 to a maximum and optimal value, defined by the ratio of resistors 42 and 43, the resistor 44 no longer intervening. The voltage thus brought to zero at 47 then acts on a complementary circuit 48, itself supplying a signal making it possible to inhibit the transistor 37 so that the voltage at 36 and consequently the chopping frequency of the final signal for controlling the transistors T1 to T4 is necessarily reduced to a value lower than the resonance frequency. This state is maintained until the lamp is again accidentally or voluntarily stopped then switched on again, in which case the frequency sweeping starts again to allow a new resonance and a reset of the arc of the lamp. Advantageously, the circuit 48 is a RESET 555 type circuit, manufactured in particular by the same companies as mentioned above.

En fonctionnement du dispositif, les impulsions issues du générateur 24, délivrées par le circuit 33 sur la connexion 25 sont acheminées après amplification conve­nable éventuelle en 49 à l'enroulement 28 du transorma­teur et soit directement vers les connexions 26 et 27 réunies aux grilles des transistors T1 et T3, soit à travers les enroulements 29 et 30 aux grilles des deux autres transistors T2 et T4, en assurant ainsi un pilotage des séquences de conduction et de blocage alternés de ces transistors, de manière symétrique et par des impulsions identiques, conformément aux dispositions mises ou eouvre de façon connue dans les appareils classiques du genre onduleurs série.In operation of the device, the pulses from the generator 24, delivered by the circuit 33 on the connection 25 are routed after suitable amplification if necessary in 49 to the winding 28 of the transformer and either directly to the connections 26 and 27 joined to the gates of the transistors T1 and T3, or through the windings 29 and 30 to the gates of the other two transistors T2 and T4, thereby ensuring control of the alternating conduction and blocking sequences of these transistors, symmetrically and by identical pulses, in accordance with arrangements made or opened in a known manner in conventional devices of the series inverter type.

La Figure 7 permet alors d'expliciter le fonction­nement particulier du générateur d'impulsions selon l'invention, lors de la phase d'allumage de la lampe où la tension de balayage est progressivement amenée à croître puis décroître avec une période prédéterminée pour assurer un balayage en fréquence adapte de la self du circuit résonnant. Les impulsions à la sortie du générateur 25 présentent en effet une fréquence variable, choisie de telle sorte qu'elle balaye de façon permanente, avec la périodicité ainsi prédéterminée, une plage de 70 à 160 kHz par exemple, et qu'elle recoupe donc nécessairement la fréquence de résonance du circuit self 19- capacité 20 ou une de ses harmoniques, en série avec la lampe 23. Simul­tanément, l'angle de passage des impulsions est maintenu constant par les résistances 42, 43 et 44 et limité à une valeur réduite, notamment de l'ordre de 5 %. Le diagramme de la Figure 7 illustre le profil des impulsions ainsi délivrées sur la connexion 25 à la sortie du générateur 24, la durée des impulsions étant d'autant plus réduite que leur fréquence est plus grande et vice versa, la quantité d'énergie correspondante restant au total identique à elle-même.FIG. 7 then makes it possible to explain the particular operation of the pulse generator according to the invention, during the lighting phase of the lamp where the scanning voltage is gradually caused to increase and then decrease with a predetermined period to ensure a Adequate frequency sweep of the choke of the resonant circuit. The pulses at the output of the generator 25 indeed have a variable frequency, chosen so that it scans permanently, with the periodicity thus predetermined, a range of 70 to 160 kHz for example, and that it therefore necessarily overlaps the resonant frequency of the self circuit 19- capacitor 20 or one of its harmonics, in series with the lamp 23. Simultaneously, the angle of passage of the pulses is kept constant by the resistors 42, 43 and 44 and limited to a reduced value , especially around 5%. The diagram of FIG. 7 illustrates the profile of the pulses thus delivered on the connection 25 at the output of the generator 24, the duration of the pulses being all the more reduced that their frequency is greater and vice versa, the quantity of corresponding energy remaining in total identical to itself.

A un moment donné au cours du balayage en fréquence ainsi réalisé, le circuit résistance self 19 - capacité 20 entre en résonance et produit aux bornes de la lampe 23 la surtension d'allumage nécessaire. La lampe s'allumant, elle débite immédiatement dans la self auxiliare 31 un courant, détecté et renvoyé vers le générateur d'impulsions 24. Celui-ci, du fait de la mise à zéro de la tension au point 47 arrête le balayage en fréquence et ramène la fréquence effective des impulsions de découpage à une valeur inférieure à la fréquence de résonance. A cet instant et comme on le voit également sur le diagramme de la Figure 7, l'angle de passage des impulsions est alors simultanément augmenté jusqu'à une valeur optimale, par exemple de l'ordre de 45 %. Dans l'exemple décrit, dès que la tension de balayage en 36 devient inférieure au tiers de sa valeur nominale, le transistor 37 est bloqué tandis que la fréquence de découpage est ramenée à sa valeur de référence, déterminée par la résistance 34 et le condensateur 35.At a given moment during the frequency sweep thus produced, the self resistance circuit 19 - capacitor 20 enters into resonance and produces, at the terminals of the lamp 23, the necessary ignition overvoltage. The lamp igniting, it immediately delivers a current, detected and returned to the pulse generator 24 to the pulse generator 24. This, due to the zeroing of the voltage at point 47 stops the frequency scanning and reduces the effective frequency of the chopping pulses to a value lower than the resonant frequency. At this instant and as can also be seen in the diagram in FIG. 7, the angle of passage of the pulses is then simultaneously increased to an optimal value, for example of the order of 45%. In the example described, as soon as the scanning voltage at 36 becomes less than a third of its nominal value, the transistor 37 is blocked while the switching frequency is brought back to its reference value, determined by the resistor 34 and the capacitor 35.

Bien entendu, il va de soi que l'invention ne se limite pas à l'exemple de réalisation plus spécialement décrit et représenté ci-dessus ; elle en embrasse au contraire toutes les variantes entrant dans le champ des revendications ci-après. Notamment, on a prévu de détecter l'allumage de la lampe par détection d'un courant dans un transformateur d'intensité ; en variante, on pourrait effectuer cette détection avec un détecteur à effet HALL ou un détecteur optique fournissant un signal de commande approprié.Of course, it goes without saying that the invention is not limited to the embodiment more specifically described and shown above; on the contrary, it embraces all the variants coming within the scope of the claims below. In particular, provision has been made to detect the ignition of the lamp by detection of a current in a current transformer; alternatively, this detection could be carried out with a HALL effect detector or an optical detector providing an appropriate control signal.

Claims (7)

1° - Procédé pour l'allumage d'une lampe à décharge, notamment du genre lampe à arc ou tube au néon, ladite lampe étant montée dans un circuit résonnant série comportant une self (19) et une capacité (20), la lampe (23) étant disposée en série avec la self et en parallèle sur la capacité, ce circuit résonnant étant disposé dans la diagonale d'un pont aux bornes duquel sont fournies des impulsions de tension délivrées par une alimentation à découpage, caractérisé en ce qu'il consiste à faire varier la fréquence de découpage des impulsions d'alimentation dans une plage de fréquences s'étendant entre deux valeurs extrêmes prédéterminées qui entourent la fréquence de résonance du circuit ou une de ses harmoniques, selon une loi approximativement linéaire, respectivement croissante puis décroissante, avec une période de balayage de cette plage donnée, à ajuster simultanément l'angle de passage des impulsions mesurant le rapport de la durée de celles-­ce à leur période à une valeur constante et limitée de telle sorte que le courant fourni à la lampe à chaque impulsion soit sensiblement réduit, puis à allumage de la lampe grâce à la surtension créée par la résonance du circuit lorsque la fréquence de découpage est égale à la fréquence de résonance ou une de ses harmoniques, à détec­ter le passage du courant dans la lampe pour ramener la fréquence des impulsions à une valeur notablement inférieure à la fréquence de résonance, l'angle de passage étant en même temps augmenté à une valeur optimale.1 ° - Method for lighting a discharge lamp, in particular of the arc lamp or neon tube type, said lamp being mounted in a series resonant circuit comprising a self (19) and a capacitor (20), the lamp (23) being arranged in series with the choke and in parallel on the capacitor, this resonant circuit being arranged in the diagonal of a bridge at the terminals of which are supplied voltage pulses supplied by a switching power supply, characterized in that it consists in varying the chopping frequency of the supply pulses in a frequency range extending between two predetermined extreme values which surround the resonant frequency of the circuit or one of its harmonics, according to an approximately linear law, respectively increasing then decreasing, with a scanning period of this given range, to simultaneously adjust the angle of passage of the pulses measuring the ratio of the duration of these to their period to a constant value and limited in such a way that the current supplied to the lamp at each pulse is appreciably reduced, then at switching on of the lamp thanks to the overvoltage created by the resonance of the circuit when the switching frequency is equal to the resonant frequency or one of its harmonics, detecting the flow of current through the lamp to reduce the frequency of the pulses to a value significantly lower than the resonant frequency, the angle of passage being at the same time increased to an optimal value. 2° - Dispositif pour la mise en oeuvre du procédé selon la revendication 1, comportant une alimentation à découpage constituée d'une source de tension (1-2) filtrée et redressée, réunie aux bornes (15-16) d'un pont compor­tant dans chacune de ses branches des interrupteurs électroniques (T1 à T4) deux à deux associés et, dans la diagonale du pont, un circuit résonnant comportant un enroulement de self (19) et une capacité (20), la lampe (23) étant montée dans cette diagonale en série avec la self et en parallèle sur la capacité, les interrupteurs (T1 à T4) étant manoeuvrés simultanément de telle sorte que les uns se ferment lorsque les autres s'ouvrent, caractérisé en ce que l'alimentation à découpage comporte un générateur d'impulsions (24) agencé de telle sorte que les impulsions aux bornes du pont présentent une fréquence variable respectivement croissante puis décroissante, en balayant une plage de fréquences s'étendant entre une valeur inférieure et une valeur supérieure à la fréquence de résonance du circuit ou une de ses harmoniques et dont l'angle de passage est faible, de telle façon qu'à la résonance le courant qui traverse la lampe et les interrupteurs soit limité à une valeur admissible, et en ce qu'il comporte en série avec la lampe, un organe détec­teur (31) du passage du courant dans cette lampe lors de son allumage de façon telle que le balayage en fréquence soit instantanément supprimé, la tension aux bornes du pont étant ramenée à une fréquence inférieure à la fréquence de résonance tandis que l'angle de passage est augmenté jusqu'à une valeur optimale.2 ° - Device for implementing the method according to claim 1, comprising a switching power supply consisting of a voltage source (1-2) filtered and rectified, joined to the terminals (15-16) of a bridge comprising in each of its branches switches electronic (T1 to T4) two by two associates and, in the diagonal of the bridge, a resonant circuit comprising a winding of inductor (19) and a capacitor (20), the lamp (23) being mounted in this diagonal in series with the self and in parallel on the capacity, the switches (T1 to T4) being operated simultaneously so that some close when the others open, characterized in that the switching power supply includes a pulse generator (24 ) arranged in such a way that the pulses at the terminals of the bridge have a variable frequency which increases respectively decreasing then decreasing, by scanning a range of frequencies extending between a value lower and a value higher than the resonant frequency of the circuit or one of its harmonics and whose angle of passage is small, so that at resonance the current flowing through the lamp and the switches is limited to an admissible value, and in that it comprises in series with the lamp, an orga detector (31) of the passage of current in this lamp when it is switched on so that the frequency sweep is instantly suppressed, the voltage at the terminals of the bridge being reduced to a frequency lower than the resonant frequency while the angle flow is increased to an optimal value. 3° - Dispositif pour la mise en oeuvre du procédé selon la revendication 2, caractérisé en ce que les interrupteurs électroniques (T1 à T4) sont constitués par des transistors recevant sur leur grille des impulsions de tension provenant du générateur et provoquant la conduction ou le blocage alterné de ces transistors.3 ° - Device for implementing the method according to claim 2, characterized in that the electronic switches (T1 to T4) consist of transistors receiving on their grid voltage pulses from the generator and causing conduction or alternating blocking of these transistors. 4° - Dispositif pour la mise en oeuvre du procédé selon la revendication 3, caractérisé en ce que les impulsions de tension sont formées à travers les enroulements d'un transformateur d'isolement (28).4 ° - Device for implementing the method according to claim 3, characterized in that the voltage pulses are formed through the windings of an isolation transformer (28). 5° - Dispositif pour la mise en oeuvre du procédé selon l'une quelconque des revendications 2 à 4, caractérisé en ce que le générateur d'impulsions (24) comprend en circuit (33) fournissant un signal en dents de scie dont l'amplitude et la période varient entre deux valeurs de coupure prédéterminées, des moyens (37 à 40) pour produire à partir de ce signal une variation de la fréquence de découpage respectivement croissante puis décroissante et des moyens (42 à 45) pour ajuster simultanément la période et la durée des impulsions de tension fournies selon la variation de la fréquence de découpage à un angle de passage présentant une valeur constante à travers toute la plage.5 ° - Device for implementing the process according to any one of claims 2 to 4, characterized in that the pulse generator (24) comprises in circuit (33) providing a sawtooth signal whose amplitude and period vary between two predetermined cut-off values , means (37 to 40) for producing from this signal a variation in the respectively increasing then decreasing switching frequency and means (42 to 45) for simultaneously adjusting the period and the duration of the voltage pulses supplied according to the variation from the switching frequency to a pass angle having a constant value across the entire range. 6° - Dispositif pour la mise en oeuvre du procédé selon la revendication 2, caractérisé en ce que le détec­teur du courant d'allumage dans la lampe est constitué par un enroulement de self complémentaire (31), disposé sur un conducteur réuni à une des électrodes de la lampe et dans lequel le passage du courant après l'allumage crée un signal de tension tel que la variation du courant ainsi détectée agisse sur le générateur d'impulsions (24) et ramène la fréquence de découpage à sa valeur inférieure dans la plage, où elle est inférieure à la fréquence de résonance, l'angle de passage des impulsions étant ramené simultanément à une valeur plus élevée.6 ° - Device for the implementation of the method according to claim 2, characterized in that the ignition current detector in the lamp is constituted by a complementary winding of self (31), arranged on a conductor joined to one of electrodes of the lamp and in which the passage of current after ignition creates a voltage signal such that the variation in current thus detected acts on the pulse generator (24) and reduces the switching frequency to its lower value in the range, where it is less than the resonant frequency, the angle of passage of the pulses being reduced simultaneously to a higher value. 7° - Dispositif pour la mise en oeuvre du procédé selon la revendication 2, caractérisé en ce que le détecteur d'allumage de la lampe est un détecteur optique ou à effet HALL.7 ° - Device for implementing the method according to claim 2, characterized in that the lamp ignition detector is an optical detector or HALL effect.
EP19870402640 1986-12-04 1987-11-24 Process and device for igniting discharge lamps Expired - Lifetime EP0271396B1 (en)

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FR8616969A FR2607996B1 (en) 1986-12-04 1986-12-04 METHOD AND DEVICE FOR IGNITION OF DISCHARGE LAMPS
FR8616969 1986-12-04

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GB2226463A (en) * 1988-12-21 1990-06-27 Sirous Yazdanian Control of fluorescent lights
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EP0408121A2 (en) * 1989-07-10 1991-01-16 Philips Electronics North America Corporation Circuit arrangement
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WO1997033456A1 (en) * 1996-03-06 1997-09-12 Robert Bosch Gmbh Circuit arrangement for igniting of high-pressure gas discharge lamps
WO1998035538A1 (en) * 1997-02-08 1998-08-13 Robert Bosch Gmbh Method for determining the resonance frequency of an electric resonant circuit
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WO2000030413A1 (en) * 1998-11-18 2000-05-25 Microlights Limited Improvements to electronic ballasts
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CN110677951A (en) * 2019-09-24 2020-01-10 华南理工大学 Full-bridge resonant circuit for ultra-high pressure mercury lamp and control method

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Cited By (29)

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GB2226463A (en) * 1988-12-21 1990-06-27 Sirous Yazdanian Control of fluorescent lights
EP0380795A1 (en) * 1989-01-30 1990-08-08 Kabushiki Kaisha Denkosha Starting device for discharge tube
US4999546A (en) * 1989-01-30 1991-03-12 Kabushiki Kaisha Denkosha Starting device for discharge tube
US5068574A (en) * 1989-01-30 1991-11-26 Kabushiki Kaisha Denkosha Lighting device for fluorescent discharge tube
EP0408121A2 (en) * 1989-07-10 1991-01-16 Philips Electronics North America Corporation Circuit arrangement
EP0408121A3 (en) * 1989-07-10 1991-10-23 North American Philips Corporation Circuit arrangement
WO1993001695A1 (en) * 1991-07-12 1993-01-21 Tridonic Bauelemente Gmbh Fluorescent lamp ballast for pulsed-mode operation
US5365151A (en) * 1991-07-12 1994-11-15 Tridonic Bauelemente Gmbh Gas discharge lamp ballast circuit with frequency modulated pulse control
GB2261332A (en) * 1991-11-06 1993-05-12 Horizon Fabrications Ltd Driving circuits for discharge devices
GB2261332B (en) * 1991-11-06 1996-05-08 Horizon Fabrications Ltd Driving circuit for electrical discharge devices
CH686390A5 (en) * 1992-10-12 1996-03-15 Juerg Nigg Gas discharge or fluorescent lamp operating system
WO1994018811A1 (en) * 1993-02-04 1994-08-18 O.C.E.M. S.P.A. Method for feeding a plurality of discharge or fluorescent lamps connected in series, and apparatus that carries out such method
WO1997033456A1 (en) * 1996-03-06 1997-09-12 Robert Bosch Gmbh Circuit arrangement for igniting of high-pressure gas discharge lamps
WO1998035538A1 (en) * 1997-02-08 1998-08-13 Robert Bosch Gmbh Method for determining the resonance frequency of an electric resonant circuit
US6546346B1 (en) 1997-02-08 2003-04-08 Robert Bosch Gmbh Method for determining the resonance frequency of an electric resonant circuit
GB2338358A (en) * 1998-06-13 1999-12-15 Simsoarica Limited High intensity discharge lamp ballast
GB2338358B (en) * 1998-06-13 2002-08-28 Simsoarica Ltd High intensity discharge lamp ballast
US6188183B1 (en) 1998-06-13 2001-02-13 Simon Richard Greenwood High intensity discharge lamp ballast
US6495971B1 (en) 1998-06-13 2002-12-17 Hatch Transformers, Inc. High intensity discharge lamp ballast
US6384544B1 (en) 1998-06-13 2002-05-07 Hatch Transformers, Inc. High intensity discharge lamp ballast
US6541923B1 (en) 1998-11-18 2003-04-01 Microlights Limited Electronic ballasts
WO2000030413A1 (en) * 1998-11-18 2000-05-25 Microlights Limited Improvements to electronic ballasts
EP1119224A1 (en) * 2000-01-19 2001-07-25 High Distribution Electrical device, in particular a fluorescent illuminating element, having a power source with a controlled converter
FR2803977A1 (en) * 2000-01-19 2001-07-20 High Distrib ELECTRIC APPARATUS, PARTICULARLY A FLUORESCENCE LIGHTING ELEMENT, HAVING A SUPPLY CIRCUIT COMPRISING A SERVO CONVERTER
EP1326486A1 (en) * 2002-01-02 2003-07-09 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Operating circuit for discharge lamps with pre-heating electrodes
US6753659B2 (en) 2002-01-02 2004-06-22 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH Operating device for discharge lamps having a preheating device
US7589480B2 (en) 2006-05-26 2009-09-15 Greenwood Soar Ip Ltd. High intensity discharge lamp ballast
CN110677951A (en) * 2019-09-24 2020-01-10 华南理工大学 Full-bridge resonant circuit for ultra-high pressure mercury lamp and control method
CN110677951B (en) * 2019-09-24 2023-12-08 华南理工大学 Full-bridge resonant circuit for ultra-high pressure mercury lamp and control method

Also Published As

Publication number Publication date
FR2607996A1 (en) 1988-06-10
EP0271396B1 (en) 1993-07-28
DE3786762T2 (en) 1993-11-11
FR2607996B1 (en) 1989-03-10
DE3786762D1 (en) 1993-09-02
ES2046212T3 (en) 1994-02-01

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