CH282532A - Device for igniting and supplying at least one luminescent tube. - Google Patents

Description

Device for priming and supplying at least one light tube. The subject of the present invention is a device for priming and supplying, from an alternating current source, at least one pressure-breaking gas-filled luminescent tube, having at least one electrode capable of being electrically heated. - tricantly at least before 1'amorgage.

Devices of this type are already known, in which the passage of the heating current is controlled automatically by contacts placed under the dependence of means which automatically cut off the current after a certain period of time, of the order of one second, and in which a strong surge ensuring the tobe's Famor@age is produced when the heating current is interrupted. These known devices, of the so-called choke type, have the disadvantage of being delicate and easily damaged.

Other devices of the type in question are known, in which manually operated contacts are provided for interrupting the heating current. The disadvantages of such non-automatic devices are 6v i- teeth.

0n still knows a third kind of amorq.age devices, comprising exclusively static means causing a strong overvoltage ensuring 1'amorgage. The heating circuit remains constantly closed, means are simply provided for automatically reducing the intensity of the heating current after ignition. This third category of devices has the disadvantage of being able to cause premature priming, that is to say before the electrodes have been brought to a sufficiently high temperature, which deteriorates the latter. Furthermore, very often, the heating current of the electrodes is not reduced to a sufficient extent after ignition; the latter are therefore very hot during operation, which shortens the duration of the tobe.

The author of the invention has found that, in many cases, the overvoltage which is applied to the tube to produce the ignition is not necessary and that, on the contrary, it has the advantage of causing the ignition. before the electrodes have been sufficiently heated.

The present invention seeks to remedy the drawbacks pointed out. The device which is the subject of the invention is characterized by a transformer of which at least a part of the primary winding is connected to RTI ID="0001.0270" WI="9" HE="3" LX="1585" LY="1788" > said source via at least one drop impedance whose total value, in operation, is at least equal to half the impedance in operation of the load circuit comprising said tube, this transformer, tor having at least one heating winding connected to the terminals of said electrode.

The appended drawing represents, by way of example, five embodiments of the device, object of the invention. Figs. 1 through 5 are respective electrical diagrams of each of the embodiments.

As far as possible, the same reference signs are used to designate the corresponding elements of the different figures.

The device represented in FIG. 1 is intended to ensure the ignition and the power supply in operation, from a source supplying an alternating voltage close to its ignition voltage, of a tube 1 filled with gas at high pressure having two electrodes capable of be electrically heated. These electrodes 2 and 2a each have two terminals respectively connected to heating windings 3 and 3a of a transformer 4 whose primary winding 5 is connected to source 6 via an impedance 7. Each of windings 3 and 3a has a common point with primary 5 of transformer 4, connected in parallel with the discharge circuit of tube 1. ment received at neutral pole 0 of source 6.

The operation of the device is as follows: Suppose that the source 6 supplies a voltage close to the voltage necessary for the ignition of the tube 1 when its electrodes 2 and 2a are heated to the desired temperature. When this source is connected to the device, an induced current flows through windings 3 and 3a and electrodes 2 and 21 are heated. When the electrodes have reached a sufficient temperature, after approximately one second, a discharge begins in the first tube 1. The discharge current passes through conductors 9 and 7.0, respectively 9a and 1.0a, connecting the electrodes 2 and 2% to the windings 3 and 3a and then passes through impedance 7. Member 14 serves to facilitate discharge initiation by increasing the potential gradient in a portion of the discharge circuit prior to initiation. Thus, in the device shown in FIG. 1, the discharge is initially initiated in the vicinity of the electrode 2. The member 14 may be constituted by an electrode placed inside the tube, by a metal coating placed on a part of the tube , or again and preferably by a metal part of a frame intended to receive the tube and which can also serve as a support for the assembly of all or part of the device. It was found that the firing of the tube was the most regular and occurred with the least high supply voltage when the conductive member was directly electrically connected RTI ID="0002.0272" WI="2" HE="4" LX="1459" LY="704"> ä, a neutral pole of the power source. However, the ignition conditions are already considerably improved when it is electrically connected. to one of the terminals of the transformer 4, either directly or through the intermediary of an impedance which the device comprises. It is obvious that, this member acting only by capacitance and its relatively low kaut capacitance, it can be connected to any one of the aforementioned points by means of an impedance of relatively high value.

We know that a light tube has, in operation, a static impedance and a dynamic impedance. Impedance sleeps. referred to in the above definition is the ratio of the mean rms voltage applied to the discharge tube or circuit comprising several tubes to the rms current passing through this discharge circuit. The total value in operation of said drop impAdance is at least equal to ä. half of the operating impedance of the discharge circuit and of the part of the primary winding connected in parallel with it, or even at least equal to the operating impedance of the circuit of discharge. Also preferably, the transformer is a high quakte closed circuit magnetic transformer and not a gap or leakage transformer or even a magnetic shunt transformer.

As soon as the tube is primed, the voltage drop across the terminals of impedance 7 causes the voltage across the terminals of part 5 of the primary winding of the tube to decrease. transformer connected to the source 6, so that the heating power supplied to the electrodes 2 and 2a by the windings 3 and 3a is reduced in very Brandes proportions.

Since the potential difference between conductors 9 and 9a is slightly greater than the potential difference between conductors 10 and 10a, the greater part of the discharge current passes through conductors 9 and flows through windings 3 and 3a and impedance 7 to source 6. Windings 3 and 3a are thus charged by the discharge current and the voltage at their respective terminals is reduced by the voltage drop produced. by the discharge current in each of these bearings. The heating voltage applied to the electrodes 2 and 2a from the windings 3 and 311 is therefore reduced. This voltage is also and it is mainly reduced due to the voltage drop produced by the discharge current crossing the impedance 7. This voltage drop has the effect of lowering in Brands proportions the voltage applied to the Primary 5 from the source 6. If the voltage of the source 6 was not quite sufficient to cause the ignition of the tube 1, this tube could still be initiated because the difference in potential between the respective ends of the electrodes 2 and 2a connected to the conductors 9 and 9a is higher than the potential difference applied to the primary 5 of the transformer and can, in certain cases, be higher than the electromotive force from source 6.

As was said above, in the positive device shown in FIG. 1, the largest part of the discharge current passes through the conductors 9 and 91. With certain tubes, this device may present disadvantages because the discharge current is not distributed uniformly in the electrodes 2 and 2a , represented by filaments. Such a filament could thus be locally overheated during operation.

This drawback can be reduced or eliminated by reversing the direction of the windings 3 and 3a, so that only a relatively small part of the discharge current passes through them. The heating current then decreases to a lesser extent after ignition, but the electrodes are heated more uniformly. It is also possible to use middle-tapped heating windings, preferably center-tapped, and connect this tap to the primary winding of the transformer. All or Part of each heating winding can be constituted by a Part of the Primary winding, the latter then having at least RTI ID="0003.0272" WI="6" HE="4" LX="1647" LY="699"> an Intermediate Hold. All or part of each heating winding can also be wound in relatively resistant wire, for example in constantan wire, always with the aim of improving the distribution of the discharge current in the electrode and to heat it more uniformly in operation.

The transformer can be a step-down or step-up autotransformer, its primary winding having an intermediate tap to which is connected one of the electrodes of the tube or one of the poles of the source, as the case may be, this same pole or said electrode being connected to the end of this winding adjacent to said socket.

The second embodiment shown in FIG. 2 is intended to ensure ignition and power supply in operation of a luminescent tube 1 having two electrodes 2 and 2a capable of being electrically heated before ignition. These electrodes are fed by windings 3 and 3a of a transformer 4 whose Primary winding 5 is connected in series with the discharge circuit and with an inductance 11. The discharge circuit and the inductance 11 are shunted by a capacitor 7, in series with winding 5, and which constitutes a drop impedance and which serves two purposes. This capacitor has an impedance at least equal to half and preferably substantially equal to that, in operation, of the discharge circuit in series with the inductor 11. current through coil 5, so that the desired voltage is applied to each of the electrodes 2 and 2a by their respective heating coils 3 and 3a. As soon as the discharge begins, the capacitor 7 is used to improve the cos (p of the device and the primary 5 is simultaneously traversed by a capacitive current passing through the capacitor 7 and by a phase current of at least 120 and, preferably, - ence, of at least 135 with respect to the first current and crossing the inductor 11 and the discharge circuit between the electrodes 2a and 2. The current resulting in the winding 5 is thus reduced in Brandes proportions, likewise the heating power supplied to the electrodes 2 and 2a through the transformer 4. The conductive member 14 is electrically received directly at the neutral pole 0 of the source. It is connected to one of the terminals of the transformer 4 by 1 through the inductor 11 and to another through the capacitor 7. This device is advantageous because the winding 5 is a low impedance winding, having a low number of turns and economical to manufacture.

The third embodiment shown in FIG. 3 is intended to ensure the amorpge and the supply of two luminescent tubes 1 and 1a. In this device, the impedance 7 at least equal to half Gelle, in operation, of the discharge circuit is constituted by an inductor, and a capacitor 12 is connected to the terminals of the source 6, in parallel with the rest of the device, to improve the cos 99 of this one. The transformer 4 comprises a primary 5 and two windings 3 and <B>31</B> respectively each supplying an electrode 2, 2 of the tubes 1 and 1a. These tubes are connected in series to the Terminals of Primary 5 and their two other electrodes 2a and 2" are heated from a winding 3b, one point of which is connected to a point of Primary 5 via a resistor 13. The electrodes 2a and 2b are connected in series to the terminals of the winding 3b, so that the heating voltage supplied by this winding is partially added, for each of the tubes 1 and 1a, to half the voltage applied. - quee to the set of Ges two tubes, between] the electrodes 2 and 2e. Under Ges conditions, it suffices that the voltage of the source 6 sofft close to the ignition voltage with heated electrodes of 1 ' together the two tubes 1 and the branches in series to ensure ignition of the tubes. Theoretically, and depending on the respective values of impedance 7 and somewhat lower than said break-in voltage. The layout of the RTI ID="0004.0272" WI="12" HE="4" LX="1111" LY="701"> windings 3, 3a and 3'' corresponds to the windings 3 and 3a of fig. 1. The resistor 13 is a high ohmic resistor intended to prevent the transformer 4 from being charged by the discharge current, at Gas where only one of the tubes 1 and 1a would be primed.

The fourth embodiment shown in FIG. 4 is intended to ensure the ignition and the power supply in operation of four tubes 1, 1a, 1b and 1e, each of the tubes having an electrode capable of being electrically heated. The arrangement corresponds to Gelle of the third embodiment shown in 1a. fig. 3, the first tube 1 of rette figure being replaced by the tubes 1 and 1a branches in series of fig. 4 and the first tube 1a of FIG. 3 being replaced by the tubes 1b and 1 branches in series of fig. 4. The electrodes 8 to 8 of this fourth embodiment, which are not electrically heated, are connected together two by two, the electrode 8 of the tube 1 to the electrode 8a of the tube ja, and so on , and the common points of Ges pairs of electrodes are joined to the sockets of the Primary 5 of the transformer by means of high ohmic resistors 13. The impedance 7 at least equal to half of Gelle, en. operation, the discharge circuit is constituted by an inductor having an intermediate tap, and a capacitor 12 is connected between this tap and the pole of the source 6 opposite to that to which the inductor 7 is connected. capacitor 12 is thus used for two purposes: it improves the cos (p of the device and it makes it possible to obtain, at the Terminals of the Primary 5, a voltage substantially greater than Gelle of the source 6. The fifth embodiment, represented at Fig. 5, is intended to supply two tubes 1 and 1a in parallel, from a supply network 6. It comprises, for each tube, a transformer connected in the same way as that to which the transformer is connected 3, 3a, 4 and 5 of the first embodiment, and a tapped inductance 7, respectively 7a, whose impedance is at least equal to half that, in operation, of the tube 1. or 1a. A capacitor 12, intended to improve the power factor, is connected between the sockets of the inductors 7 and 7a which form, with the primaries 5 and <B>51</B> of the transformers, a bridge connected to the. lattice 6 into two of its opposite vertices. This arrangement is absolutely symmetrical, from the electrical point of view, and thereby greatly reduces the stroboscopic effect due to the low inertia of the tubes, and greatly amplified by an asymmetry, which is difficult to avoid, under the conditions of priming of each tube. To obtain this result, the tubes thus supplied must be adjacent to each other.

In the embodiments represented in FIGS. 1, 3, 4 and 5, it will be noted that or, primaries 5 and 5a are only slightly or not charged by the discharge current, so that this primary can be wound in relatively fine wire. The windings 3, 3a and <B>3'</B> and 3c must be wound in wire of stronger section and be able to support the heating current of the electrodes 2 to 2 before. ignition, and the reduced heating current of these electrodes after ignition, in certain cases, added to all or part of the discharge current.

The impedances 7 and 71 of these same embodiments could also be constituted by capacitors, or even by resistors. However, impedances consisting of inductors are preferable from all points of view.

The devices described are particularly advantageous because they do not include any moving parts and any contact liable to oxidize or be burned. ignition, they are only charged because of the heating power which they supply to the electrodes of the tubes.These transformers can, therefore, be wound on cores of small dimensions, their primary being made of fine wire and comprising a large number of turns, so as to present a high value inductance and to consume only a very low magnetization current.The transformer of the second embodiment described has the advantage of comprising only a small number of coils, this transformer being a low impedance transformer whose primary is connected in series with the discharge circuit and with an inductance.These positive devices are, consequently, economical while being very efficient. By way of example, a device has been produced intended to ensure the ignition and the supply, directly from a 220 volt alternating current distribution network, of a tube having an operating voltage of 110 volts. and consuming 40 watts. With this device, mounted according to the diagram of FIG. 1, the heating current before ignition was about 1 ampere for each of the two electrodes and fell to 0.6 amperes after 0.6 seconds and to 0.08 amperes after ignition. Priming was carried out very regularly and the tubes tested burned for the duration guaranteed by the manufacturer and with the prescribed priming frequency of one priming every three hours of service, without the slightest trace of blackening occurring at the vicinity. swimming electrodes or elsewhere.

Claims (12)

CLAIM: Device for initiating and supplying, from a source of native alternating current, at least one low-pressure gas-filled luminescent tube, having at least one electrode capable of being electrically heated at least before ignition, device characterized by a transformer of which at least part of the primary winding is connected to said source via at least one drop impedance whose total value, in operation, is at least equal to half the operating impedance of the discharge circuit comprising said tube, this transformer having at least one heating bearing connected to the terminals of said electrode. 1. Device according to claim, characterized in that the discharge circuit is connected in parallel with at least part of the primary winding of the transformer, and in that the said heating winding has at least one common point. with this winding. 2. Device according to claim and sub-claim 1, characterized in that the total value in operation of said drop impedance is at least equal to the impedance in operation of the discharge circuit and of the part of said winding. connected in parallel with it. 3. Device according to claim, characterized in that the total operating value of said drop impedance is at least equal to the operating impedance of the discharge circuit. 4. Device according to claim, characterized in that said transformer has a so-called closed magnetic circuit. 5. Device according to claim and sub-claim 1, characterized in that said drop impedance is an inductor having an intermediate tap and in that it comprises a capacitor connected between this intermediate tap and an input terminal of the device opposite to that connected to said inductor, this capacitor serving to improve the <I>cos</I> (p of the device and, together with a part of said inductor, to be supplied before ignition, across the terminals of said part of the primary winding of the transformer connected to the source through this inductance, a voltage higher than that of the source, but insufficient to cause premature ignition. 6. Device according to claim, for aL1 at least two luminescent tubes connected in series, characterized in that the transformer comprises at least two heating coils each connected to the terminals of at least one electrode, at least one electrode of each tube being connected to one of said heating coils. 7. Device according to claim, characterized in that the discharge circuit is connected in series with the primary winding of the transformer and with an inductor, and in that the discharge circuit and this inductor are shunted by a capacitor constituting said drop impedance. 8. Device according to claim and. Sub-claim 7, characterized in that the said inductor has in operation a united impedance such that the impedance in operation of the discharge circuit in series with this inductor is substantially equal to the impedance of the said capacitor. 9. Device according to claim, characterized in that it further comprises at least one conductive member disposed in the vicinity of at least part of the discharge path and electrically connected to one of the terminals of said transformer. . 10. Device according to claim and sub-claim 9, characterized in that said conductive member consists of a metal part of an armature intended to receive said tube. 17.. Device according to claim and sub-claims 9 and 7.0, characterized in that said armature also serves as a support for the entire device. 12. Device according to claim and sub-claim 9, characterized in that said member is directly electrically connected to a neutral pole presented by said source, this pole being connected to one of the terminals of the transformer.