EP0113725A1

EP0113725A1 - Ignition device for discharge lamps

Info

Publication number: EP0113725A1
Application number: EP19830900617
Authority: EP
Inventors: Jean-Marie De Pra; Ugo De Pra
Original assignee: PRA UGO DE
Current assignee: PRA UGO DE
Priority date: 1982-02-03
Filing date: 1983-02-03
Publication date: 1984-07-25
Also published as: LU83920A1; EP0105042A1; WO1983002871A1

Abstract

Ce dispositif se raccorde par deux bornes d'accès (A, B) aux électrodes d'une lampe à décharge, ce dispositif étant alimenté par la tension cyclique du réseau à travers un ballast et les électrodes de ladite lampe. Il comporte des moyens statiques réalisant la fonction préchauffage (23 à 29) de la lampe pendant un temps dépendant des fluctuations du réseau et la fonction d'élaboration d'une impulsion de tension (7 à 22) n'advenant qu'après le temps de préchauffage. Il comporte également une protection (6, 30). Exemple d'application intéresant pour des tubes à décharge fluorescent de 36 et 58 W.This device is connected by two access terminals (A, B) to the electrodes of a discharge lamp, this device being supplied by the cyclic voltage of the network through a ballast and the electrodes of said lamp. It comprises static means carrying out the preheating function (23 to 29) of the lamp for a time dependent on the fluctuations of the network and the function of developing a voltage pulse (7 to 22) occurring only after the time preheating. It also includes protection (6, 30). Example of interesting application for fluorescent discharge tubes of 36 and 58 W.

Description

Starting device for discharge lamps

The present invention relates generally to a starting device for discharge lamps connecting by two access terminals to the electrodes of a discharge lamp, the device being supplied by the cyclic voltage of the network through a reactive ballast and the electrodes of said lamp.

The most widely used starting device comprises a glow discharge switch connected in parallel to the discharge tube and in series with the filaments of this tube, the alternative source, a commissioning switch and a- self stabilizer or ballast. The device has the drawback that the tube does not light up until after a certain number of awkward ignition attempts which affect the user and alter the life of the tube. Another drawback lies in the fact that the proper functioning of this device strongly depends on the temperature conditions, fluctuations in the network voltage as well as the aging of the tube and of the glow discharge switch.

More sophisticated devices, preventing flashing on ignition, exist but they generally include a mechanical element. This has the disadvantage of a lifetime linked to the number of requests.

There are also entirely static devices which operate, however with more or less satisfaction. Indeed, the proper functioning of these devices is only ensured within narrow limits of ambient temperature and fluctuation of the network voltage. Static devices often include inductors and / or more than two access terminals. In addition, they prove unable to properly ignite the new generation fluorescent tubes and more particularly the tubes.

OM of 36 and 58 W which replace the tubes of 40 and 60 W. The present invention aims to provide a new electronic starting device for discharge lamps not having the aforementioned drawbacks and advantageously designed in such a way

- that it produces an almost instantaneous ignition, without flashing,

- that it has an almost unlimited lifespan and

- that it operates in a very wide range of ambient temperature and even for temperatures below 0 ° C.

The aim of the invention is achieved by providing a starting device for discharge lamps which is connected by two access terminals to the electrodes of a discharge lamp, this device being supplied by the cyclic voltage of the network through a reactive ballast and the electrodes of said lamp, characterized in that it comprises static means performing the functions: adequate preheating of the lamp for a time dependent on fluctuations in »the voltage of the supply network and generation of a pulse of voltage adaptable to the type of lamp to be lit, the voltage pulse occurring only after the preheating time of the lamp. This device can also advantageously include a fully static protection which ensures that it is automatically switched off in the event of the tube not being ignited after a few ignition attempts. This can happen when the tube is at the end of its life. Adopting an adequate preheating time that adapts "naturally" to fluctuations in the supply network voltage, followed by a pulse occurring after this preheating time, largely eliminates the reduction in useful life of the tube which depends, among other things, on the number of ignition stresses.

f OMP The present invention is described in more detail by means of the example embodiments explained below. The following figures illustrate the various preferred embodiments without, however, limiting the scope of the present invention.

FIG. 1 shows a device for igniting discharge lamps belonging to the state of the art; Figure 2 - shows an electronic diagram being the basic cir¬ cooked of the present invention; FIG. 3 shows the circuit of FIG. 2 where the configuration of the circuit has been changed in order to be able to use higher ignition voltages; FIG. 4 gives the appearance of the voltage across the terminals of the device of the invention and of the current passing through it; FIG. 5 shows the circuit of FIG. 3 in which two additional terminals have been removed; Figure 6 i shows a way of connecting two tubes; FIG. 7 shows another embodiment of the invention in which another type of semiconductor switch is used; FIG. 8 shows the circuit of FIG. 7 modified to obtain an advantageous control of the semiconductor switches;

FIG. 9 shows another embodiment of the invention in which a third type of semiconductor switch is used; FIG. 10 shows the circuit of FIG. 9 modified to avoid re-priming of the preheating switch during the release of the pulse; Figure 11 shows the circuit of Figure 10 modified to be able to use higher starting voltages; FIG. 12 shows an embodiment of a circuit part making it possible to make even higher ignition voltages usable; Figures 13 and 14 show other means for simultaneously lighting two tubes;

Figure 15 shows another arrangement of the device of the invention in the circuit including the tube; Figure 16 shows another embodiment of the invention allowing the connection according to Figure 15;

Figure 17 shows another embodiment allowing the connection according to Figure 15; and FIG. 18 shows the shapes of the network voltages and at the terminals of the tube as well as the shape of the preheating current for the circuits of FIGS. 16 and 17. Identical references are used for identical or similar elements.

The device of the state of the art, represented in FIG. 1, comprises a lumi¬ nescent discharge switch 2, connected in parallel to the fluorescent discharge tube 1 and in series with the filaments l 'of this tube, the source alternative 4, the start-up switch 3 and a stabilizing choke or ballast 5. The life of the tube 1 depends on its use and on the number of ignitions, itself depending on the aging of the elements 1 and 2.

The device of the invention, the basic circuit of which is shown in FIG. 2, is subdivided into three functional parts; a) the elements 22 to 29 ensuring a preheating of the tube for a period depending on fluctuations in the voltage of the supply network, comprising at least one semiconductor switch 29 of the thyristor or triac type and a control circuit 23 to 28 rendered inactive during the rise of the priming pulse. b) the elements 7 to 21, forming a "forced switching" circuit, transferring the preheating current towards it at a determined time and delivering after this transfer, a voltage pulse initiating the tube, this part of the circuit comprising at least one semiconductor switch whose ignition, controlled by a circuit 7, 8, 9, 10, 11, 12, 13 in which the voltage rises in stages, depends, among other things, on the voltage drop across a resistor 16 while the preheating current is flowing and also comprising a means for producing a high voltage 17 to 21, c) a part guaranteeing a fully static protection consisting of a limitation of the voltage and / or a reduction of the current which traverses the device at a negligible value after a time ^" determined if the lamp does not light up. According to the invention, the control circuit of the semiconductor switch of the preheating function comprises a divider circuit of the resistor type 27 in series with another resistor 24 connected in parallel on a capacitor 23. According to the embodiment shown in FIG. 2, the semiconductor switch for the preheating function is a thyristor 29 or a functioning triac as a thyristor. According to the embodiment of FIG. 2, the semiconductor switch of the part of the circuit establishing a high voltage, is a component of the TRIAC 17 type, when the trigger circuit of the pulse is charged for 1 alternation for which the potential of B is higher than the potential of A. According to the invention, the means for producing a high voltage consists of a capacitor 20 in series with a diode 18 itself connected in parallel on a resistor 19 , all in series with the diode 21 in parallel on the triac 17. The basic circuit of the device of the invention shown in FIG. 2 operates as follows: during the alternation where the terminal A is positive with respect to terminal B (positive alternation), the first capacitor 23 charges through the diode 28 according to a law which depends on the resistors 24 and 27. When the voltage across the terminals of the capacitor 23 reaches the trigger voltage of the DIAC 26 (element also known under the name of "bi-directional Silicon trigger device"), it sends through the resistor 25 and the diac 26 a current pulse in the trigger of the thyristor 29 which becomes conducting. Consequently, a current flows through the ballast 5 (FIG. 1), the filaments l 'of the tube 1, the protection 6, the diode 28, the thyristor 29 and the resistor 16.

This current which is used to preheat the tube starts to flow in. The alternation where the potential of A is positive compared to that of B and stops by the presence of the self inductance of -ballast, when the potential of B is already become positive with respect to the potential of A. The uni-directional shape of this current is shown in Figure 4 (II). Note that the potential difference across the resistor 16 is the image of the ^' preheating current. This process is repeated for several cycles until the circuit consisting of elements 7 to 21 changes the

. system regime. While the preheating ends at each half cycle where the potential of B is positive compared to that of A, the following three events take place in the circuit made up of elements 7 to 21. 1) the capacitor 9 is charged according to a time constant essentially dependent on resistors 8 and 10 at a voltage whose value mainly depends on the dimensioning of elements 8, 9 and 10. Note that the presence of diode 7 allows this capacitor to charge in a unidirectional manner and to discharge through the resistor 10, during a cycle of the AC source: the capacitor 9 therefore charges and discharges once per cycle (the diode 7 could be eliminated, but this would result in greater dissipated power in items 8 and 10).

2) The capacitor 13 is charged by the current which passes through the resistor 12 and the diode 11. The elements 12 and 13 are chosen so that the voltage

~ - J * ^~ * E OM of the capacitor 13 rises in stages at each alter¬ nance where the potential of B is positive compared to that of A. The capacitor 13 does not discharge once per cycle like the capacitor 9. 3) The capacitor 20 charges through the resistor 19 and the diode 21 approximately at the peak value of the network voltage and remains charged at this value as long as the triac 17 is not started.

When the voltage at the terminals of 13, added to the voltage at the terminals of the resistor 16 (voltage which exists when the preheating current flows), reaches the triggering voltage of diac 15, the triac 17 is triggered. The triac 17 is triggered therefore takes place during the circulation of the preheating current, and as soon as it passes the capacitor 20 forces the current to cancel in the thyristor 29. Note that the diode 22 connected between the means to produce a pulse of high voltage 17 to 21 and the control circuit of the preheating function 23 to 28 prevents the ignition of the thyristor 29 during the release of the ignition pulse of the tube by putting the potential of the connection between 25 and 26 to the potential of the cathode of 29.

After the tripping of 17, the voltage across the tube goes from an almost zero value to a negative value (point B of potential greater than A) which is that of the voltage of the capacitor 20. The current which passed through the thyristor 29 is transferred to the branch made up of elements 17, 18 and 20. ^' The voltage across the terminals of capacitor 20 is gradually reversed according to a law which depends on the self inductance of the ballast 5, on the resistances of the circuit

⁽ resistance of the ballast 5, of the filaments 1 ′, of the element 6, of the resistances 27 and 16) and of the capacity of the element 20.

OMP One of the parameters which governs the choice of the condenser 20 is that the value of the time of the interval t -t. (see Figure 4 curve I) during which the capacitor 20 discharges, must be greater than the recovery time of the thyristor 29.

The shape of the preheating current during the forced switching phase is also given in Figure 4.

It will be noted that the current is canceled in 20 when the voltage across the tube (therefore across the capacitor 20) goes through its maximum.

It is obvious that if the elements are well chosen, the priming of the tube begins before the maximum tension is reached. FIG. 4 therefore shows, for reasons of clarification, the voltage present at the terminals of the tube when the latter does not light up, in other words the full pulse of the ignition voltage. The aim here is to show that we have mastered the possibility of setting the following parameters:

1) the time interval t -t. (essentially by the choice of element 20 and instant to, '

2) the maximum amplitude of the voltage (by the choice of element 20 and of instant t _Q ,

3) the instant when the forced switching is caused, that is to say the instant t (by the choice of 16 and of the elements which govern the evolution of the voltage across the capacitor 13). After passing through the maximum voltage across the tube, the decrease in the voltage across 20 occurs in an oscillating circuit whose choice of damping is set by resistors 19, 25 and 27. In fact the reverse current its sense of ^" circulation after passing through the maximum voltage and it must pass through the resistor 19 and the diode 21 due to the presence of the diode 18. It should be noted that once the tube is primed, the voltage present at terminals A and B is such that:

f OMP 1) the thyristor 29 never starts because the voltage across the terminals of 23 always remains lower than the voltage of the diac 26,

2) the triac 17 never starts because the voltage at the terminals of 13 will cap at a value much lower than that of tripping of the diac 15,

3) the current consumption in the whole circuit is very low as well as the power dissipated.

The protection of the device is carried out by means of a resistor VDR (voltage dependent resistor) 30 to avoid exceeding the voltage withstand of the components and by means of a nonlinear resistor 6, of PTC type (positive temperature coefficient thermistor) to limit the current to a negligible value if the lamp does not light after a few attempts to start.

It can therefore be seen that if the network voltage decreases, the preheating current decreases, but the time delay for the release of the ignition pulse is also modified by means of both a slower evolution of the voltage at the terminals of 13 and a voltage lower than the terminals of 16. On the other hand if the network voltage increases, the opposite effect occurs: the preheating time is shorter and the priming pulse of the tube is delivered earlier. An advantage of the device of the invention therefore lies in this "natural adaptation" effect to fluctuations in the network voltage. Another advantage is that the tube ignition pulse in the event after a time preheat Fage ^• adequate, very largely eliminates the diminu¬ tion of the useful life of the tube depends on the number - of solicitations ignition, among others.

An additional advantage is that this device can work with ordinary ballasts. The device of the invention is connected to the same place as the device of the state of the art (FIG. 2);

OMP so we ^'had to use the existing pipe supports.

The device of the invention has an almost unlimited lifetime considering the use of semiconductors and passi s entirely static elements. It has no mechanical element subject to wear.

According to the invention, the device provides pulses largely exceeding 1000 V for a voltage network of 220 V - 15% with a good level of energy. Another advantage of the invention consists in that it operates in a very wide range of ambient temperature and even at temperatures below 0 C. ^e

Taking into account the current state of the thyristor technology (sensitivity of the trigger - withstand voltage - cost) we will preferably use the circuit of figure 3 when we want ignition pulses higher than 700 V.

This assembly remains within the framework of the invention and adds interesting particularities to the circuit of FIG. 2.

Only the topology of the circuitry intended for preheating has changed. The thyristor 29 in FIG. 2 has been replaced by the thyristors 31 and 32. The resistor 27 forming a divider with the resistor 24 in FIG. 2 has been replaced by the resistors 34 and 35 which allow, in addition to the role played by 27 , to distribute the voltage of the ignition pulse between the thyristors 31, 32 when they have been blocked by the capacitor 20 and the voltage pulse is in the direct direction (potential A higher than that of B) .

L ^r .amorçage 31 and 32 occurs as follows: when the voltage 23 reaches the voltage déclenche¬ ment of the diac 26, the thyristor 32 is initiated and thereby cause the initiation of 31 because the capacitor 23 can supply a current pulse in the trigger of the thyristor 31 via the diode 33 and the thyristor 32 which has just turned on. The advantage of the change made in the part intended for preheating is to be able to admit pulse voltages of double value compared to the circuit of figure 2 when using for elements 31 and 32 of the same type as 29 (figure 2 ).

The cascading ignition of 31 and 32 is possible in the preheating phase since there is at this time, at terminals A and B, only the network voltage which is much lower than the voltage withstand of each of the 2 thyristors.

After blocking of 31 and 32 by the capacitor 20, following the priming of the triac 17, the triggers of 31 and 32 are brought back practically to the potential of B by the diode 22. This will prevent a reclosing of 31 and 32 during the duration of the priming pulse.

FIG. 5 shows a variant of the embodiment shown in FIG. 3. Two additional terminals C and D have been created by opening the connection between the thyristors 31 and 32. It may be noted that it is indifferent to open the link between 31 and 32 above the potential link connecting the connection between resistors 34 and 35 and the electrodes- connected in series of 31 and 32, or below this link as shown in Figure 5. This connected variant as shown in Figure 6, where the reference 36 represents the circuit of Figure 5, allows the priming of the two tubes L1 and L2.

The short-circuit of terminals C and D makes the circuit of Figure 5 strictly equivalent to that of Figure 3. Thus by a very simple modification of the circuit of Figure 3 consisting of the addition of two auxiliary terminals C and D, it is possible to obtain ^• a bipolar electronic starting device which can be used as well: a) for priming a single fluorescent tube connected between terminals A and B, terminals C and D then being short-circuited; b) to start two fluorescent tubes L1, L2 mounted in series, the terminals C and D then being connected according to 'FIG. 6 where the filaments FI and F2 of the tube L1 are respectively connected to the terminal A and to the terminal C, while that the filaments FI and F2 of the tube L2 are respectively connected to terminal D and to terminal B; the filament F2 of the tube L1 and the filament FI of the tube L2 being themselves connected in series. Figure 7 is another variant of the invention. The part intended for preheating is presented in a manner similar to that of FIG. 2 (elements 22 to 30) but certain components are dimensioned differently. The semiconductor switch 37 is a thyristor type component, which means that the control circuit must accumulate energy during the alternation for which the potential of A is higher than the potential. from B. A second difference with FIG. 2 is that the voltages of the control circuit 12, 13, 23, 24,27, 28 of the semiconductor switch 37 also depend on the voltages applied to the control circuit 23,24, 27, 28 of the semiconductor switch 29 of the preheating function ^* by the pooling of a resistor 24 in parallel on a capacitor 23. The diode 11 prevents the capacitor

13 to discharge by means other than that passing through the resistor 14, the diac 15 and the trigger of the thyristor 37. The discharge of the capacitor 13 and the subsequent ignition of the thyristor 37 also occur as in the circuit of FIG. 2, when the voltage across the capacitor 13 added to that present across the resistor 16 reaches the trigger threshold of the diac 15. The diodes 18, 21, 22, the resistor 19 and the capacitor 20 retain roles identical to those described in the explanations relating to the

- B-E

OP Figure 2. It is obvious that we can, from the circuit of Figure 7, develop a circuit having the same purpose as that of Figure 3, namely the possibility of producing high pulses by replacing thyristor 29 by two thyristors 31 and 32 as shown in figure 3. The transposition of the "preheating" part of the circuit of figure 3 to that of figure 7 being done in an obvious way, it was not considered useful to draw it but it is of course another variant of the invention.

FIG. 8 shows an improvement of the circuit of FIG. 7 by making the ignition circuit of the thyristor 37 less dependent on the tolerances of the diacs 15 and 26; This can be advantageously achieved by eliminating the capacitance 23 of the preheating control circuit, by replacing the common resistor 24 of the preheating control circuit and of the control circuit of the pulse-releasing switch with a capacitor 39 and a resistor 38 , put in parallel, by adding a resistor 40 in series with the elements 38, 39 above and by inserting a capacitor 41 in parallel on the preceding elements 38, 39 and on the resistor 40. This obviously supposes an adequate dimensioning of the elements 38 to 40. FIG. 9 shows another preferred embodiment of the invention in which the number of power semiconductor components is reduced to the unit. Advances in GTO thyristor technology (SCR's Turn-off) allow us to envisage a device according to the invention, the circuit ensuring the so-called heating function comprises a semiconductor switch of the GTO 42 type initiated by a circuit of RC command and blocked by a blocking circuit taking into account the preheating time and of which a circuit for developing a voltage pulse supplies a pulse after the blocking of said GTO. The GTO blocking circuit takes into account the adequate preheating by the resistor 16 which adds its potential difference which is the image of the preheating current to a potential difference increasing in stages in a capacitor 13 blocking the GTO 42 semiconductor when its poten¬ tiel is high enough. Elements 23 to 27 and 45 are intended to initiate the GTO 42 to produce preheating by the circulation of a uni¬ directional current as in the preceding circuits. This preheating current flows in the direction of terminal A, element 6, GTO 42, resistor 16, terminal B. The originality of the GTO with respect to the thyristor is that it can be blocked by a sufficient current pulse in the trigger, this current having the opposite direction to that which produces the priming of the GTO. The operating principle is analogous to that of the circuits of FIGS. 2 and 3: the capacitor 13 charges in stages in the negative voltage alternations of the source (potential of B greater than the potential of A) and sends the pulse of blocking at the GTO 42 as soon as the voltage at its terminals plus the voltage at the terminals of the resistor 16 reaches the voltage of the diac threshold 15. The current which passed through the GTO 42 before its blocking is transferred to the branch made up of the capacitors 20 and diode 18. A voltage pulse which is only limited by the choice of the blocking instant, various resistances (filament - ballast - PTC 6 - resistors 16 and 27), the self-induction coefficient of the ballast 5, VDR resistance 30 and capacity 20, arises ^; and initiates the fluorescent tube.

Note that the capacity 20, unlike the cases of the circuits of Figures 2, 3, 5, 7 and 8 is not charged, at the time of blocking of the GTO 42, at the value of the peak voltage of the network in the direction AB, but to a value which depends on the voltage of the network existing at 1 ^• boot 42 and the dimensioning of the resistor 19. After the passage by the maximum voltage at the terminals of the tube, the decrease in the voltage at the terminals of the capacitor 20 occurs in an oscillating circuit whose choice of damping is fixed by the resistors 19 and 27. The opto-coupler 44 avoids a reboot semiconductor (GTO) 42, by its photo-transistor. This opto-coupler 44 keeps the capacitor 23 discharged for the duration of the voltage pulse across the tube. This supposes elements dimensioned in such a way that the blocking pulse supplied by the capacitor 13 and a part of which passes through the LED component of the opto-coupler 44, this LED being connected in series with the limiting resistor 43, lasts long enough. Another particularly preferred embodiment of the invention is shown in FIG. 10. It includes a means for reducing the duration of the pulse supplied by the capacitor 13 of the unlocking circuit of the GTO 42. This said means advantageously consists of a VDR resistor 47 activating the base of a transistor 49 in parallel on the capacitor 23 of the ignition circuit of the GTO, this transistor 49 avoiding a loading of said capacitor 23, As soon as the threshold of VDR 47 is reached by the pulse voltage, a current flows in the base of the transistor 49 through the diode 45, the VDR 47 and the resistor 48. The capacitor 23 can no longer charge as long as this base current flows. The VDR 47 is chosen so that its threshold is higher than the peak voltage of the network so as to allow current to flow only during the voltage pulse.

It goes without saying that the means reducing the duration of the pulse supplied by the capacitor 13 can consist of an avalanche diode activating the base of a transistor 49 in parallel on the capacitor 23 of the ignition circuit of the GTO. Said means can also be advantageously replaced by any element sensitive to tension.

OMP known per se, such as a spark gap etc., without departing from the scope of the present invention.

A particularly preferred embodiment of the invention which allows the use of high pulse voltage levels is shown in Figure II. In this example, the circuit providing the preheating function comprises a thyristor 51 in series with the GTO 42 so that these semiconductors are started in cascade and that a higher voltage level is obtained. The pulse voltage is distributed over the elements 42 and 51 via the resistors 54 and 50. The cascading ignition of the GTO 42 and of the thyristor 51 occurs according to the same principle as for the circuit of FIG. 3: when 42 is primed, the impulse provided by 23 can pass through the trigger of 51 through the resistor 25, the diode 53, the trigger of 51, and the GTO 42 which has primed. Note that the circuits derived from those of FIGS. 9, 10 and 11 which would use only part or even delete the elements 18, 19 and 20 would only represent a particular degenerate form of these circuits; which means that such circuits would only constitute an unmarked form of the invention ^" and could in no case constitute a novelty or be used outside of this invention.

The circuit shown in FIG. 12 makes it possible advantageously to benefit from a high voltage level, for example greater than 2000 V, by using three thyristors 56, 57, 58 primed in cascade. Indeed, it suffices to replace, in the case of FIGS. 3, 7, 8, the circuit part located to the right of the diode 22 by the circuit of FIG. 12.

The resistors 55, 61, 62 make it possible to distribute the high direct voltage, existing when the priming pulse of the tube takes place, over the three thyristors

O PI 56, 57 and 58; which means that the assembly can hold practically three times the voltage which each of the three thyristors can block, in the direct direction.

The principle of cascading ignition shown in Figure 12 can obviously be extended to a higher number of thyristors. It can also be transposed to the circuits of Figures 9, 10 and 11 without departing from the scope of the invention.

For the circuits of FIGS. 9, 10 and 11, the thyristor 58 is replaced by the GTO 42.

In another example of application, it may be advantageous to connect, in parallel to the resistor 16 of the circuits of FIGS. 2, 3, 5, 7 and 8, a voltage limiting device which ensures that the preheating current is cut off at a value which does not fluctuate as a function of the voltage variations of the AC source. This would draw the advantage of a reduced dimensioning of the capacity 20. The same device transposed in the circuits of FIGS. 9, 10 and 11 would have the advantage of. require a smaller GTO 42 blocking pulse and therefore fewer means to produce it.

Such a voltage limiting device can consist for example of diodes connected in series or of a zener diode. Another way of using the invention to ignite two tubes simultaneously is shown in Figures 13 and 14. The device 64 of Figure 13, the details of which are given in Figure 14, is connected to two tubes L1 and L2. connected to the supply network through ballasts 5 and 65. The transformation of the dipole device of FIG. 2 into a quadrupole device as shown in FIG. 14, consists essentially of adding the elements 66 to 72 and removing the terminals E and F The addition of means 69, 70, 71 comparable to means 18, 19, 20 makes it possible to produce a voltage pulse which ignites the second tube. Diodes 67 and 68 allow

WIPO to keep the two pulses separate and individualized at the level of each of the tubes.

The major advantages of this configuration compared to that of FIG. 5 are in particular: I ^e . This configuration allows, by means of an obvious transposition to the diagram of FIG. 3, to obtain higher voltage pulses for each tube. 2 ". The addition of elements similar to elements 68 to 72 and connected in a similar manner makes it possible to light a number of additional tubes corresponding to the number of circuits used constituted by these elements, two additional terminals being output for each addition.

Two remarks can still be made concerning these devices for multi-tube ignition:

1. The tube connected on the A-B side plays the pilot tube sheet in the sense that a triggering of the resistance P.T.C. 6 stops the operation of all the tubes connected to the device. On the other hand, the deterioration of any of the other tubes connected to the device does not prevent the others from operating.

2. The preheating current of all the tubes connected to the device passes through the thyristor 29 (or the thyristors 31, 32 in the diagram in FIG. 3). So far, only the use of a so-called "uncompensated" arrangement has been described. For various reasons, known per se, it may be necessary to use a compensation capacitor 73, in series with the ballast 5, as shown in FIG. 15. The devices described above, due to the ^" uni-directional nature of the current preheating, do not allow to light a tube connected according to Figure 15. However, by making the preheating current bidirectional, it is possible to use the principles described above and to light a tube fluorescent connected as shown in Figure 15. The device 74 of Figure 15 includes the means necessary for this purpose.

One way of using these means is shown in FIG. 16. The device described in FIG. 3 has been taken up by adding the elements 75 to 81 which allow the passage of a preheating current in the direction BA and thus ensure a bidirectional character in preheating. The elements 75 to 81 can be arranged so that the triac _. 76 is replaced by a conductive thyristor in the BA direction without bringing a different character to the device 74. The diode 75 allows the elements 76 to 81 not to have to withstand high voltage when the ignition pulse is released from the tube, while the diode 22 plays the same role as before, namely 1 inactivation of the ignition circuit 31 and 32 during the release of the above pulse.

Figure 18 explains very well the shapes of the voltages, respectively, of the network and at the terminals of the tube, as well as the shape of the preheating current during the period preceding, as in that which follows, the ignition of the tube.

The period t -t represents the shapes during preheating. The section t _? -t, represents the end of the preheating period. At time t ₃ , the ignition pulse is released. From t., The transitional ignition stage (not shown) having passed, we find the system established. It can be seen, without going into details, that the charging of the capacity 13 still takes place as in the case of uncompensated mounting, when the potential of B is greater than that of A and before activation of the triac 76, and that the ignition pulse is released, when the voltage across the terminals of the capacitor 13 added to the voltage drop across the resistor 16, caused by the preheating current flowing in the direction AB reaches the starting voltage of the diac 15.

In the case where the starting voltage can be limited to values compatible with the voltage withstand of the elements, an advantageous execution of the device 74 can be presented as shown in FIG. 17. A single bidirectional switch 22 of the triac type replaces the three switches 31, 32 and 76 in FIG. 16. The triac 82's priming circuit, comprising the elements 23 to 27, 83 and 84, makes it possible to prime the triac 82 in both directions and thus give the bidirectional character to the pre-heating current. The diode 22 always plays the role of making the triac 82's ignition circuit inactive during the release of the ignition pulse from the tube.

It is understood that the device 74 makes it possible to light a tube in an uncompensated arrangement as well as in a compensated arrangement and therefore confers a universal character on these devices.

In general, it should be noted that a discharge resis¬, carefully dimensioned, can be connected in parallel on the capacitor 13 of the devices described from the start. This makes it possible to start the device under ideal initial conditions and thus avoid a premature ignition pulse which could occur if the capacitor 13 had an initial charge, a vestige of a previous ignition. It is obvious that any electronic component can be replaced by equivalent components or circuits known per se without bringing anything new to the present invention. It is, moreover, obvious that any simplification of the circuits presented in the figures represents only a degenerate form of the invention. The detailed explanations given above clearly show the advantages of the device of the present invention over the state of the art. By choosing a clever and cumbersome arrangement of the circuits, it is possible to use the device of the invention in existing installations.

Claims

claims

1. Starting device for discharge lamps connecting via two access terminals (A, B) to the electrodes of a discharge lamp (1), this device being supplied by the cyclic voltage of the network through a ballast reagent (5) and the electrodes (1 ') of said lamp, characterized in that it comprises static means performing the functions: adequate preheating of the lamp for a time dependent on fluctuations in the voltage of the supply network and processing of a voltage pulse adaptable to the type of lamp to be switched on, the voltage pulse only occurring after the lamp preheating time.

2. Device according to claim 1 characterized in that it includes a fully static protection which ensures its automatic switching off in the event of non-ignition of the tube after a few ignition attempts.

3. Device according to claim 2 characterized in that the protection consists in a reduction of the cou¬ rantqui travels the device to a negligible value after a determined time, if the lamp does not light and / or in a voltage limitation priming.

4. Device according to claim 3 characterized in that the protection is carried out by means of a VDR resistance (voltage depend resistor) (30) to avoid exceeding the voltage withstand of the components and by means of a resistance non-linear (6), PTC type (positive temperature coefficient thermistor) put in series with all the components of the device to limit the current to a negligible value if the 'lamp does not light after a few attempts to start.

5. Device according to one of the preceding claims, characterized in that the preheating function comprises at least one semiconductor switch (29) of the thyristor or triac type and a control circuit (23 to 28) made inactive during the rise in the priming pulse.

6. Device according to one of the preceding claims, characterized in that the part of the circuit which generates the ignition pulse comprises at least one semiconductor switch, the ignition of which is controlled by a circuit in which the voltage rises in stages ( 7, 8, 9, 10, 11, 12, 13) depends, among other things, on the voltage drop across a resistor (16) while the preheating current is flowing and also comprising means for producing a high voltage (17, 18, 19, 20, 21).

7. Device according to one of the preceding claims, characterized in that it comprises a diode (22) connected between the means for producing a high voltage pulse (17 to 21) and the circuit for controlling the preheating function (23 to 28), preventing reactivation of the preheating circuit during the release of the priming pulse from the tube.

8. Device according to claim 5 characterized in that the preheating function is carried out by means of two thyristors (31, 32) primed in cascade.

9. Device according to claim 5 characterized in that the preheating function is performed by means of three thyristors (58, 57, 56) primed in cascade.

10. Device according to claims 5 and 8 characterized in that two additional terminals are created (C, D) by opening the connection between the two thyristors (31, 32).

11. Device according to claim 6 characterized in that the semiconductor switch is a triac type component (17) when the trigger circuit of the pulse is charged when the potential of B is "higher than the potential of A or a thyristor type component (37) when the control circuit accumulates energy during the alternation for which the potential of A is higher than the potential of B.

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12. Device according to claim 6 characterized in that the voltages of the control circuit (12, 13, 23, 24, 27) of the semiconductor switch (37) ensuring the release of the pulse also depend on the applied voltages to the control circuit (23, 24, 27 ⁾ of the semiconductor switch (29) beyond the preheating function by pooling a resistor ⁽ 24 ⁾ in parallel on a capacitor (23).

13. Device according to claim 12 characterized in that the capacity (23) of the preheating control circuit is eliminated, in that the resis¬ tance (24) common to the preheating control circuit and to the control circuit of the semiconductor switch releasing the pulse by a capacitor (39) and a resistor (38) placed in parallel, in that a resistor (40) is added in series with the elements (38 , 39) above and in that a capacitor (41) is inserted in parallel on the elements (38, 39), themselves in parallel, and on the resistor (40).

14. Device according to claim 6 caracté¬ ized in that the means for producing a high voltage consists of a capacitor (20) in series with a diode (18) in parallel on a resistor (19), all in series with the triac 17 in parallel on the diode 21.

15. Device according to claim 1 caracté¬ ized in that the circuit ensuring the preheating function comprises a semiconductor switch of the GTO type (Gâte turn Off SCR's) (42) initiated by an RC control circuit and blocked by a blocking circuit taking account of the preheating time and in that a cir¬ cuit for developing a voltage pulse provides a pulse. after blocking said GTO.

16. Device according to claim 15 characterized in that said blocking circuit of the GTO takes account of adequate preheating by the resistor ⁽ 16 ⁾ ° which adds its potential difference which is the image of the preheating current at a potential difference increasing by stages in a capacitor ⁽ 13 ⁾ , this sufficiently high potential difference blocking the GTO semiconductor (42).

17. Device according to claims 15 and 16 characterized in that an optocoupler (44) avoids a reboot of the GTO semiconductor.

18. Device according to claims 15 and 16 characterized in that it comprises means for reducing the duration of the pulse supplied by the capacity (13) of the blocking circuit of the GTO and for preventing its re-ignition.

19. Device according to claim 18 characterized in that said means consists of a VDR resistor ^' (47) or an avalanche diode, activating the base of a transistor (49) in parallel on the capacitor (23) of the circuit. the GTO, this - transistor (49) avoiding the charging of the capacitor (23) during the release of the priming pulse from the tube.

20. Device according to claims 15 to 19 characterized in that the circuit 'ensuring the preheating function comprises at least one thyristor (51) in series with the GTO (42) so that these semiconductors are initiated in cascade .

21. Device according to any one of the preceding claims, characterized in that a voltage limiting device is connected in parallel to the resistor (16) providing the image of the preheating current to the circuit releasing the priming pulse. tub.

22. Device according to any one of the preceding reven¬ dications characterized in that it comprises -. again one or more times the circuit (68 to 72) making it possible to produce a voltage pulse, so as to ignite two or more tubes synchronously, the pulses being individualized at the level of each tube.

23. Device according to any one of the preceding reven¬ dications characterized in that it also comprises a circuit (75 to 81) which also allows the passage of a preheating current in the direction BA, the circulation of the bidirectional current being ensured, on the one hand, from A to B, as in the device of the preceding claims and, on the other hand, from B to A, by the control of the thyristor or triac (76) of the complementary circuit (75 to 81).

24. Device according to any one of reven¬ dications 1 to 22 characterized in that it provides bidirectional preheating comprising a single power element of the triac type (82) connected to the means intended to produce an impulse as in the device of previous claims.

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