LU83920A1 - STARTING DEVICE FOR DISCHARGE LAMPS - Google Patents

Description

V

»» 1.

Starting device for discharge lamps.

The present invention relates generally to a starting device for discharge lamps which is connected 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 common 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 start-up switch and a stabilizing choke. or ballast. The device has the drawback that the tube does not light until after a certain number of troublesome ignition attempts for the user and alters 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 drawback of a lifetime linked to the number of requests-25 citations.

There are also fully static devices that work, however with varying degrees of satisfaction. Indeed, the proper functioning of these devices is only ensured within narrow limits of ambient temperature and fluctuation in the network voltage. Static devices often include inductors and / or more than two access terminals. In addition, they prove to be incapable of correctly lighting the new generation 35 J fluorescent tubes and more particularly the 2 -.- \ 36 and 58 W tubes which replace the 40 and 60 W tubes.

The present invention aims to provide a new electronic starting device for discharge lamps not having the aforementioned drawbacks 5 and advantageously designed in such a way that - it produces an almost instantaneous ignition, without blinking, - that it has a duration almost unlimited life and, - it operates in a very wide range of 10 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 15 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 includes 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 voltage adaptable to the type of lamp to be switched on, the voltage pulse only occurring after the lamp warm-up time.

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 lit after a few ignition attempts. This can happen when the tube is at the end of its life. The adoption of an adequate preheating time adapting "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 on the number of ignition stresses.

i \ 3.,.

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, being limiting in the field 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 circuit 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 shape of the voltage across the terminals of the device of the invention as well as the shape of the current passing through the circuit;

Figure 5 shows the circuit of Figure 3 in which two additional terminals have been taken out to connect a second tube;

Figure 6 shows how to connect two tubes to the circuit of Figure 5;

Figure 7 shows another embodiment of the invention, in which the configuration of Figure 3 has been changed due to the use of another type of semiconductor switch;

FIG. 8 shows the circuit of FIG. 7 in which certain additional precautions have been taken for the advantageous control of the semiconductor switches;

FIG. 9 shows another embodiment of the invention in which a third type of semiconductor switch is used; Î Figure 10 shows the circuit of Figure 9 for which the configuration has been modified using a means other than Figure 9 to avoid ____ a re-ignition of the switch of t 4 \ * r preheating during the release of 1 ' impulse ;

FIG. 11 shows the circuit of FIG. 10 in which the configuration 5 has been modified in order to be able to use higher starter voltages,

FIG. 12 shows an embodiment of a part of the circuit replacing the corresponding part of the circuits of FIGS. 2, 3, 7 and 8 and 10 making it possible to make even higher initiation voltages - d1.

Identical marks are used for identical or similar elements.

The prior art device, represented in FIG. 1, comprises a glow discharge switch 2, connected in parallel to the fluorescent discharge tube 1 and in series with the filaments 1 ′ of this tube, the alternative source 4, the commissioning 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 dependent 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 network voltage supply, comprising at least one semiconductor switch 29 of the thyristor type 30 and a control circuit 23 to 27 made inactive during the rise of the ignition pulse, b) the elements 7 to 21, forming a circuit "forced switching", transferring the preheating current to it at a determined time and delivering after this transfer,

A voltage pulse priming the tube, this part of the circuit comprising at least one semiconductor switch whose priming, controlled by a 5 * r 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 circulating and also comprising means for producing a high voltage 18, 19, 20, c) a part guaranteeing fully static protection consisting of a voltage limitation and / or a reduction of the current which flows through the device to a negligible value after a determined time if the lamp does not light up.

According to the invention, the control circuit of the semiconductor switch for the preheating function comprises a divider circuit of the resistor type 27 in series with another resistor 24 connected in parallel 15 to a capacitor 23.

According to the embodiment shown in Figure 2,; the semiconductor switch for the preheating function is a thyristor 29.

According to the embodiment of FIG. 2, the semiconductor inter-interrupter of the part of the circuit establishing a high voltage is a component of the TRIAC 17 type, when the triggering circuit of the pulse is charged during l 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 to a resistor 19.

The basic circuit of the device of the invention 30 shown in FIG. 2 operates as follows: during the alternation where the terminal A is positive relative to the terminal B (positive alternation), the capacitor 23 is charged through the diode 28 according to a law which depends on resistors 24 and 27. When the voltage 35 across the capacitor 23 reaches the voltage of η triggering of the DIAC 26 (element also known as i 6 \ sends through the resistor 25 and the diac 26 a pulse of current in the trigger of the thyristor 29 which becomes conducting. Consequently, a current crosses the ballast 5 (figure 1), the filaments 1 '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 begins to circulate 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 the 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 15 16 is the image of the preheating current. This process is repeated for several cycles until the circuit made up of elements 7 to 21 modifies the system speed. While the preheating ends at each alternation where the potential of B is positive compared to that of A, the following three events occur in the circuit made up of elements 7 to 21.

1) The capacitor 9 charges according to a time constant essentially dependent on the resistors 8 and 10 at a voltage whose value depends mainly on the dimensioning of the elements 8, 9 and 10. Note that the presence of the diode 7 allows this capacitor to charge in a unidirectional way and to discharge through the resistor 10, during a cycle of the alternative source: the capacitor 9 charges 30 and consequently discharges once per cycle (the diode 7 could be deleted, but this would result in greater dissipated power in elements 8 and 10).

2) The capacitor 13 is charged by the current which passes λ through the resistor 12 and the diode 11. The elements 12 and 13 are chosen so that the voltage \ 7 * t 'of the capacitor 13 rises in stages at each alternation where the potential of B is positive compared to that of A.

5 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 to the peak value of the network voltage and remains charged at this value until the triac 17 is 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 the diac 15, the triac 17 is triggered 17. The triac triggering 17 therefore takes place during the circulation of the preheating current and as soon as it flows, the capacitor 20 forces the current to cancel in the thyristor 29.

20 Note that the diode 22 connected between the means for producing a high voltage pulse 18, 19, 20 and the control circuit of the preheating function 23 to 27 prevents the ignition of the thyristor 29 during the release of the pulse of priming the tube by setting 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 terminals of the tube goes from a virtually 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 capacitor 20 gradually reverses according to a law which depends on the self-inductance of the ballast 5, the resistances of circuit A (resistance of the ballast 5, of the filaments 1 ′, of the element 6, of the resistors 27 and 16) and the capacity of element 20.

% 8

One of the parameters which govern the choice of the capacitor 20 is that the value of the time of the interval I

tQ-t ^ (see Figure 4 curve I) during which the capacitor 20 discharges, must be greater than the 5 recovery time of the thyristor 29.

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

It will be noted that the current is canceled out in 20 * when the voltage at the terminals of the tube (therefore at the terminals 10 of the capacitor 20) passes by 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 15 of the tube when the latter does not light up, in other words the full pulse of the ignition voltage. The goal here is to show that we master the possibility of fixing the following parameters: 1) the time interval t ^ -t ^ iessentially by the choice of the element 20 and of the instant t, 2) the maximum amplitude of the voltage (by the choice of the element 20 and of the instant tQ, 3) the instant when one causes the forced commutation that is to say the instant t ^ (by the choice of 16 25 and of the elements which govern the evolution of the voltage across the capacitor 13).

After passing through the maximum voltage at the terminals of the tube, the decrease in the voltage at the terminals of 20 occurs in an oscillating circuit whose choice of damping is set by resistors 19, 25 and 27. In fact the current reverses its direction of flow 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 35 that once the tube is primed, the voltage present at the 1 terminals A and B is such that: 9 \ 1) the thyristor 29 never starts because the voltage at the terminals of 23 always remains lower than the voltage of the diac 26, 2) the triac 17 does not start never because the voltage at the 5 terminals of 13 will cap at a value significantly 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 VDR resistor (voltage dependent resistor) 30 * to avoid exceeding the voltage withstand of the components and by means of a non-linear resistor 6, of the PTC type (positive temperature coefficient thermistor) to limit the current to a negligible value if the lamp does not light up after a few attempts to start it.

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 25 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 consists in that the priming pulse of the tube, occurring after an adequate preheating time, eliminates very largely the reduction in the useful life of the tube which depends on the number of ignition stresses, among others.

An additional advantage is that this device can work with ordinary ballasts.

The device of the invention plugs into the same place. v that the device of the state of the art (Figure 2); 10 -c "τ * therefore the existing tube supports can be used.

The device of the invention has an almost unlimited lifespan given the use of semiconductors and the 5 elements, entirely static passive. It has no mechanical element subject to wear.

According to the invention, the device supplies pulses largely exceeding 1000 V for a network of. 220 V voltage - 15% with a good level of energy.

Another advantage of the invention is that it operates in a very wide range of ambient temperature and even for temperatures below 0 ° C.

Given the current state of thyristor technology (sensitivity of the trigger-withstand voltage-cost 15) we will preferably use the circuit of Figure 3 when we want ignition pulses greater than 700 V.

This assembly remains within the framework of the invention and adds interesting particularities to circuit 20 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. 25 2 has been replaced by the resistors 34 and 35 which, in addition to the role played by 27, to distribute the voltage of the priming pulse between the thyristors 31, 32 when they have been blocked by the capacitor 20 and the voltage pulse is in the forward direction 30 (potential A higher than that of B).

The priming of 31 and 32 occurs as follows: when the voltage of 23 reaches the tripping voltage of the diac 26, the thyristor 32 starts and therefore causes the priming of 31 because the capacitor 23 can supply a current pulse in the trigger of the thyristor Jf 31 via the diode 33 and the thyristor 32 which has just lit.

11 ...

\ 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 elements for the same type as 29 are used for 31 and 32 ( 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 thyris-> 10 tors.

After the 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 avoid a reclosing of 15 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 connection between 31 and 32 above the equi-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 variant connected as shown in FIG. 6, where the reference 36 represents the circuit of FIG. 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 j 30 circuit of Figure 3 consisting of the addition of! two auxiliary terminals C and D, it is possible to obtain i a bipolar electronic starting device which can be used as well: a) for the ignition of a single fluorescent tube connected IB5 between terminals A and B, terminals C and D being Jf then short-circuited; 3L · 12 b) to start two fluorescent tubes LI, L2 connected in series, the terminals C and D then being connected ï according to FIG. 6 where the filaments Fl and F2 of the tube L1 are respectively connected to the terminal A and 5 at the terminal C, while the filaments F1 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 F1 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 similar way to that of FIG. 2 (elements 22 to 30) but certain components are dimensioned differently. The semiconductor switch 37 is a component 15 of the thyristor type, which means that the control circuit must accumulate energy during the alternation for which the potential, of A is higher than the potential of B. A second difference with FIG. 2 is that the voltages of the control circuit 20 12, 13, 23, 24, 27 of the semiconductor switch 37 also depend on the voltages applied to the control circuit 23, 24, 27 of the semiconductor switch 29 for the preheating function by pooling a resistor 24 in parallel with 25 a capacitor 23. The diode 11 prevents the capacitor 13 from discharging by a different route 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 terminals of the capacitor 13 added to that present across the terminals of the res istance 16 reaches the trigger point of the diac 15. The diodes 18, 21, 22, the resistor 19 and the capacitor 20 retain identical roles 35 to those described in the explanations relating to the i 13

NOT

figure 2. It is quite obvious that one can, starting from 1 of the circuit of figure 7, develop a circuit having I the same goal as that of figure 3, namely the possibility | the ability to produce high pulses by replacing the thyristor 29 with two thyristors 31 and 132 as shown in FIG. 3. The transposition of the "preheating" part of the circuit of FIG. 3 to that of FIG. 7 obviously, it was not considered useful to draw it but it constitutes of course another variant of the invention.

I ”Figure 8 shows an improvement in the circuit of | FIG. 7 by making the priming circuit of the B thyristor 37 less dependent on the tolerances of the diacs 15 | and 26; This can advantageously be carried out by removing the capacitance 23 from the preheating control circuit, by replacing the common resistor 24 of the preheating control circuit and the control circuit of the pulse-releasing switch with a capacity 39 and a resistor 38, put in parallel, by adding a resistor 40 in series with the preceding elements 38, 39 and by inserting a capacitor 41 in parallel on the preceding elements 38, 39 and on the resistor 40. This obviously requires dimensioning items 38 to 40.

Figure 9 shows another preferred embodiment of the invention where the number of semiconductor components. of power is reduced to the unit. Advances in GTO thyristor technology (SCR's Turn-off) allow 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 RC command and | blocked by a blocking circuit taking account of the preheating time and of which a circuit for generating * 35 a voltage pulse supplies a pulse after L · “* ~“ * “'' '' 14 \ ^ tÊÊ • r hold account of 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 by stages in a capacitor 13 blocking the GTO semiconductor 42 when its potential difference is. high enough. Elements 23 to 27 and 45 are intended to initiate the GTO 42 to produce preheating by the circulation of a unidirectional current as in the preceding circuits.

* 10 This preheating current flows in the direction terminal A, element 6, GTO 42, resistance 16, terminal B. The originality of the GTO compared 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 is charged in stages in the negative voltage alternations of the source (potential of B greater than the potential of A) and sends the blocking pulse. at the GTO 42 as soon as the voltage at its terminals plus the voltage at the terminals of the resistor 16 reaches the threshold voltage of the diac 15. The current which passed through the GTO 42 before it is blocked is transferred to the branch made up of the capacitors 20 and of the 25 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 30 and initiates the fluorescent tube.

Let us note that the capacity 20, contrary to 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, with the value of the peak voltage of the network in the direction AB , but 135 well at a value which depends on the voltage of the existing network at the time of priming of 42 as well as on the dimensioning of the resistance 19. After the passage A- 15 ...

\ by the maximum voltage across the tube, the decrease in voltage across the capacitor 20 occurs in an oscillating circuit whose choice of damping is set by resistors 19 and 27.

The opto-coupler 44 avoids a reboot of the 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 dimension-10 elements born in such a way that the blocking pulse supplied by the capacitor 13 and 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 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 20 VDR resistor 47 activating the base of a transistor 49 in parallel on the capacitance 23 of the ignition circuit of the GTO, this transistor 49 avoiding a loading of said capacitance 23. As soon as the threshold of the VDR 47 is reached by the voltage pulse, a current flows in the base of the transistor 25 49 passing through the diode 45, the VDR 47 and the resistor 48. The capacitor 23 can no longer charge as long as this * current .base circulates. The VDR 47 is chosen so that its threshold is greater than the peak voltage of the network so as to allow current 30 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 λ 35 of the GTO. Said means can also be replaced J / advantageously by any element sensitive to tension, 16

NOT

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 makes it possible to use high pulse voltage levels is shown in FIG. 11. In this example, the circuit ensuring the preheating function comprises a thyristor 51 in series with the GTO 42 so that these semiconductors are cascaded and 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 pulse provided by 23 can pass through the trigger of 51 via 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 a part or even delete 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 Figure 12 advantageously benefits from a high voltage level, for example greater than. 2000 V, using three thyristors 56, 30 57, 58 primed in cascade. Indeed, it suffices to replace, in the case of FIGS. 3, 7, 8, the part of the circuit 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 forward voltage, existing when the priming pulse of the tube takes place, on the three thyristors __ ’\ 17 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.

5 The principle of cascading ignition shown in FIG. 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.

10 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 that does not fluctuate. . not according to the voltage variations of the AC source. This would draw the advantage of a reduced dimensioning of the capacity 20. The same device 20 transposed into the circuits of FIGS. 9, 10 and 11 would have the advantage of requiring a smaller blocking pulse from the GTO 42 and therefore means reduced to produce it.

Such a voltage limiting device can consist for example of diodes connected in series or of a zener diode.

* It is obvious that any electronic component S 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 \ ^ 1 \ 18 and space-saving layout of.,; circuits, it is possible to use the device of the invention in existing installations.

..l ·

Claims (24)

1. Starting device for discharge lamps connecting by 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 reactive ballast (5) and the electrodes (1 ') of said lamp, characterized in that it includes static means performing the functions: adequate preheating of lamp 10 for a time dependent on fluctuations in the supply network voltage and generation of a voltage pulse adaptable to the type of lamp to be lit, the voltage pulse only occurring after the lamp preheating time. 15 2. Device according to Claim 1, characterized in that it includes an entirely static protection which ensures that it is automatically switched off in the event of the tube not igniting after a few ignition attempts. 3. Device according to claim 2 characterized in that the protection consists in a limitation of the voltage and / or in a reduction of the current which traverses the device to a negligible value after a determined time, if the lamp does not light up . 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 non-resistance linear (6), PTC type (positive temperature coefficient thermistor) 30 connected 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 ignition attempts. 5. Device according to one of the preceding claims, characterized in that the pre-heating function comprises at least one semiconductor switch I (29) of the thyristor type and a control circuit (23 to 27) t --- ---- • in 6. Device according to one of the preceding claims B 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 by steps (7, 8, 9f 10, 11, 12, 13) depends, among other things, on the B voltage drop across a resistor (16) while m the preheating current is flowing and comprising 1 also means for produce a high voltage 1 10 (18, 19, 20). ] 7. Device according to one of claims; previous characterized in that it comprises a diode (22) connected between the means for producing a high voltage pulse "(18, 19, 20) and the control circuit 15 of the preheating function (23 to 27), preventing the 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 control circuit of the semiconductor switch for the preheating function comprises a divider circuit of the resistor type in series (27) with another resistor (24) connected in parallel to a capacitor (23). 9. Device according to claim 5 characterized in that the preheating function is carried out by means of two thyristors (31, 32) primed in cascade. 10. Device according to claim 5 characterized • in that the preheating function is performed by means of three thyristors (58, 57, 56) primed in cascade. 11. Device according to claims 5 and 9 characterized in that two additional terminals are created (C, D) by opening the connection between the two thyristors (31, 32). 12. Device according to Claim 6, characterized in that the semiconductor switch is a component I of the triac type (17) when the trigger circuit vk of the pulse is charged when the potential of B is higher than the potential of A. 4 21 'r'> 13. Device according to claim 6 characterized in that the semiconductor switch is 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. 14. 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 voltages applied to the control circuit (23, 24, 27) of the semiconductor switch (29) of the preheating function by, a pooling of a resistor (24) in parallel on a capacitor (23). 15. Device according to Claim 14, characterized in that the capacity (23) of the preheating control circuit is eliminated, in that the resistor (24) common to the preheating control circuit and to the control circuit is replaced. of the semiconductor switch 20 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 preceding elements (38, 39) and in that a capacitor (41) is inserted in parallel on the elements (38, 39), themselves in parallel, and on the resistor (40). 16. Device according to claim 6 characterized 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). 17. Device according to claim 1 characterized in that the circuit ensuring the preheating function t comprises a semiconductor switch of the GTO type (Gate turn Off SCR's) (42) initiated by an RC control circuit and blocked by a blocking taking account of the preheating time and in that a circuit for developing a voltage pulse supplies a pulse after the blocking of said GTO. 11 18. Device according to claim 17 Jaj characterized in that said blocking circuit of the GTO: ¾¾ takes account of the adequate preheating by the resistor (16) which adds its potential difference which is the image of the preheating current to a difference of ί increasing potential by level in a capacitor (13),, * B this sufficiently high potential difference 1 blocking the GTO semiconductor (42). $ 19. Device according to claims 17 and 18 10 characterized in that an optocoupler (44) avoids a reboot of the GTO semiconductor. 20. Device according to claims 17 and 18 characterized in that it comprises a means for reducing the duration of the pulse supplied by the capacity (13) of the blocking circuit of the GTO. 21. Device according to claim 20, characterized in that said means 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 20 GTO, this transistor (49) avoiding the charging of the capacitor (23) during the release of the priming pulse from the tube. 22. Device according to claim 20 characterized in that said means consists of an avalanche diode activating the base of a transistor (49) in parallel on the capacitor (23) of the ignition circuit of the GTO, this transistor (49 ) avoiding the charging of the capacitor (23) during the release of the priming pulse from the tube. 23. Device according to claims 17 to 22 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 i are started in cascade . 24. Device according to any one of the preceding claims, characterized in. which is connected 35. a voltage limiting device in parallel on the t resistor (16) providing the image of the preheating current to the circuit releasing the priming pulse from the tube. ____- 23.,: N