US2588858A - Circuit arrangement for discharge tubes, particularly glow discharge tubes - Google Patents

Description

March 11, 1952 FALEHMANN 2,588,858

CIRCUIT ARRANGEMENT FOR DISCHARGE TUBES, PARTICULARLY GLOW DISCHARGE TUBES Filed Sept. 28, 1948 5 Sheets-Sheet l vol %&%%L%

March 11, 1952 F LEI-[MANN 2 588,858

CIRCUIT ARRANGEMENT FR DISCHARGE TUBES, PARTICULARIIY GLOW DISCHARGE TUBES Filed Sept. 28, 1948 v 5 Sheets-Sheet 2 6 (2 f m i I .4. 5 I? 2c 73% A g i II -'ma v:

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March 11, 1952 EHMANN 2 588,858

F. L CIRCUIT ARRANGEMENT FOR DISCHARGE TUBES, PARTICULARL Y GLOW DISCHARGE TUBES Filed Sept. 28, 1948 5 Sheets-Sheet 3 Patented Mar. 11, 1952 CIRCUIT ARRANGEMENT FOR DISCHARGE TUBES, PARTICULARLY GLOW DIS- CHARGE TUBES Frantisek Lehmann, Chomutov, Czechosiovakia Application September 28, 1948, Serial No. 51,608 In Czechoslovakia October 7, 1947 7 Claims.

The discharge tubes and more particularly the glow discharge tubes, which due to their low current requirements and other advantages have been more widely used recently, show in practical utilisation certain less favourable characteristics which are inherent to such tubes and for the elimination of'which a number of methods have been proposed directed more particularly to the circuit arrangement of the tubes. Those characteristics of the discharge tubes towhich the proposed improvements relate substantially have bearing on the ignition difliculti'es, the stabilisation necessity, the flickering in each half cycle '(strob'oscopic effect) and on the unfavourable alteration of the phase shift of the network current due to the use of choke coils.

However, the means hitherto proposed permit to eliminate usually a single of the diflicul'ties referred to andare complicated in themselves so that a combination of such proposed means, which sation of "their current, the elimination of the strobo'scopic efiec't and a compensation of the .phase shift are obtained at the same time.

In accordance with the present invention the desired effect is achieved by connecting each of the discharge tubes to the same phase of the network in series with an inductance, a capacity being connected up in parallel with at least each alternate discharge tube and with a part of its series connected inductance adjacent to the network, while a further capacity is connected up in the circuit of at least one discharge'tube'in series with the latter.

'In a circuit arrangement for two or three discharge tubesit is sufficient to 'connec't'up thesaid furlther capacity only in the circuit of one of the tubes; with Tfour discharge tubes the capacity referred will .be connected up in two circuits etc.

The aforementioned parallel capacities by means of which resonant circuits 'for the ignition proper are obtained should be connected up in parallel with at least "each alternate discharge tube, as stated ereinbeiore; of course they may be included also in the circuits of more than each alternate discharge tube, and if desired in the circuit of all the discharge tubes.

If the parallel ignition capacities are included only in the circuits of some of the discharge tubes, first those discharge tubes are ignited whose circuits include the said capacities and then the ignition of the other tubes takes place. For this purpose such ignition circuits are practically quite sufficient in which the corresponding ignition voltages approximate more or less the resonant voltage. A particularly advantageous arrangement is obtained when the resonances, even partial ones, in the circuits of the various discharge tubes are produced by the effect of higher, may be different, harmonics of frequences contained in the network current.

In the circuit arrangements of the invention relatively very small ignition condensers are quite suiiicient; this is of advantage not only from the aspect of losses and thus of economy of operation but also in view of the stability of the discharge. Indeed, too large condensers connected up in parallel to the discharge tubes usually lead to flickermg.

In accordance with the invention, certain portions of the inductances comiected in series with the discharge tubes may be used at the same time in the circuits of two or more discharge tubes. As is explained in connection with the example described in the body of the specification, a particularly advantageous arrangement is that one, in which a portion of the inductances :is made common to the circuits of at least two discharge tubes, the said common portion being that one which is adjacent to the network.

The inductances which are connected up in the circuits of the various discharge tubes may be formed by a number of choke coils, preferably two choke coils. These component chokes, if desired together with the chokes from the circuits of the other discharge tubes, may be assembled into a structural unit. In this connection it is of advantage to make use of a combined choke coil which preferably maybe formed of Term-- magnetic, especially iron spools as disclosed in my application Ser. No. 767,275, filed August 7, 1947, now abandoned.

Further details and possibilities of application of the circuit arrangement for discharge tubes in accordance with the present invention are disclosed in the following description of examples in conjunction with the accompanying drawings inwhich Fig. '1 shows 'a circuit arrangement for two glow discharge tubes in which ignition capacities are connected up in both circuits and the series connected inductances are formed each by two independent chokes;

Fig. 2 represents a similar circuit arrangement as that shown in Fig. 2, but for three glow dis charge tubes;

Fig. 3 shows a circuit arrangement for two glow discharge tubes in which a choke is used in common for the two circuits;

Fig. l shows a similar circuit arrangement as that of Fig. 3, but for three glow discharged tubes;

Fig. represents a circuit arrangement similar to that of Fig. 3 in which, however, a combined coil choke is used, and

Fig. 6 shows a similar circuit arrangement as that of Fig. 5, but for four glow discharged tubes.

The circuit arrangements shown in Fig. 1 and likewise in Fig. 2 represent, as far as the use of the individual components is concerned, one of, the.

most perfect embodiments of the invention, and accordingly these examples are the most suitable for explaining in detail the circuit arrangement.

In the circuit arrangement shown in Fig. 1 the terminals and 2 of a single phase low voltage source of alternating current have connected thereto a main ignition'circuit, which consists of a choke 3 and a condenser 4, a glow discharge tube 5 being connected to the plates of the condenser over a stabilising choke B. The chokes 3 and 6 form together the stabilisation impedance of the glow discharge tube 5, and the ignition condenser 4 is so selected as to produce a resonant efiect with the choke 3 preferably for any higher harmonic of the supply network current. When the terminals I and 2 havebeen connected to the network an increased voltage is obtained on the condenser 4 and this voltage leads to the ignition of the glow discharge tube 5. In accordance with the present invention this circuit arrangement, which is substantially known per se, has connected in parallel the circuit of another glow discharge tube 1 which differs from the aforedescribed circuit in that the stabilisation impedance in addition to the chokes 8, 9 comprises a condenser l0. The values of the choke 8 and of the condenser H in the ignition circuit are selected preferably in such a way that resonance is obtained in this circuit for a different higher harmonic than in the ignition circuit of the glow discharge tube 5. V

The circuit arrangement just described secures aninstantaneousignition of the two glow discharge tubes 5 and 1 even at a lower supply volt- 7 age and without preheating the electrodes. Un-

der the influence of the condensers used the dark periods overlap each other on the'lighting tubes so that permanently at least one of the glow discharge tubes emits light whereby the strobes'copic effect, which often is very troublesome, is

eliminated in a relatively simple way. The condensers connected up in the circuit, especially the condenser Hi, exert an influence on the power factor of the supply network and not only can completely compensate the harmful phase shift produced by the chokes employed, but also when necessary they can insure an over-compensation of the said shift.'

For the sake of completeness numerical indicai tions will be given for a typical practically tested embodiment of the above described circuit arrangement in accordance with the present invention. With standard glow discharge tubes having an input power of 40 watts at a voltage of 220 volts on the terminals i and 2, a choke 3 was used having an inductance of 1.18 henrys and a condenser l having a capacity of l microfarad, these values corresponding to a resonance for the third harmonic of an alternating current of 50 cycles/sec. Upon switching on the current from the network an ignition voltage of 280 volts was measured on the terminals of the condenser 4 which voltage was reduced to 105 volts after the ignition was completed. With a stabilising choke 5 having an inductance of 0.58 henry, a current of 0.5 ampere was obtained through the glow discharge tube 5 in stabilised condition and a current of 0.13 ampere through the condenser 4.

. In the ignition circuit of the glow discharge tube 1 a choke 8 of 0.53 henry and a condenser I l of 3 microfarads were used, which values correthrough the choke 8.

The power factor of the lighting current was compensated to 0.9. It was found that the sum total of the capacities of the condensers used was lower than the total capacity which would be otherwise required for such a compensation of the phase shift. w

Still better results areobtained when the circuit arrangement in accordance with the present invention is used for three glow discharge tubes as is shown in Fig. 2. In addition to the components i to H which are formed in the same Way and denoted by the same reference numerals as in Fig. l, the parallel by connected circuit of the glow discharge tube [2 is used and this last mentioned circuit corresponds to the circuit of the glow discharge tube 5.-

In connection with the numerical values of the components inthe just described example, it should be noted that the values in the two circuits of the glow discharge tubes 5 and 1 are also the same as'in the first example. In the ignition circuit of discharge tube l2 the same inductance of the choke l3 was used as that of the choke 3 and the capacity of the condenser 15 1 was 2 microfarads so that a resonance for the discharge tube, a current of 0.136 ampere flowed through the condenser l5 and a current of 0.45 ampere flowed through the choke l3. 7

The circuit arrangement as thus far described may be applied in similar way also for a larger number of discharge tubes. Thus, for instance,

' in a parallel connection of fourdischarge tubes it is possible to combine two pairs of discharge tubes which are-connected up as shown in Fig. 1, and by this method the combination may be -further developed for a larger number of discharge tubes. Y

The other examples shown represent simplified circuit arrangements in accordance with the pres- V ent invention. Thus Fig. 3 shows a parallel connection of two glow discharge tubes 5 and 1, the

tissues-a circuit of the-glow discharge tubeb being quite similar to the arrangement of Fig. 1, while the second glow discharge tube "I Iisconnected over *portions of its stabilisin'g circuit directly to the terminal I of the network, andis connected to the terminal 2 of thentwork behind the choke 3. The supply con ductors of the glow discharge tube 1 include the chokes 8 and!) corresponding to the chokes 3 and 6,'the equalising condenser being connected up between the choke 9 and the network. The ignition condenser l l is connected in parallel with the glow "discharge tube 1-to the choke 9 and condenser 'lll'and consti- "tutes the ignition circuitwith the chokes '3 and 8. .An'advantageof this arrangement consistsmore particularlyi'n'the Simultaneous utilisation of the choke 3 for'the series circuits of both glow discharge tubes and 1 whereby the material for "the otherwise'neees'sary second choke is saved and this single "choke '3 "view of the predominantlyind'uctive load in the circuit "or the 'glowdischarge tube 5 and the capacitive loa'd'in the 'circuitof the glow discharge "tube 1, the totalworking current flowing through the choke 3 is extraordinarily small because the a 'just me'ntionedcurrents neutralise each other in maybe very small sincejin the choke. Moreover, in viewof the fact that in the ignition circuitof the glow discharge tube 1 the two chokes 3 and 8 are in series and therefore their inductancesare added to each other,a frelatively'small condenser H is sufiicient for an appropriate increase in the ignition voltage.

As it has been stated hereinbefore usually it is not necessary in these'casesthat a complete resonance should beobtained in theignition circults, it being sufl'icient to obtain-a voltage lower :thanthe resonant voltage in order toimpress 'on the terminals of the tube at leasttheignition voltage. This remark'applies to both the last mentioned ignitioncircuits, i.-e.for the circuits includingthe condenser I l and the condenser 4.

4 Another advantage of the aforedescribed sim- "IpIified arrangement consists in the possibilityof "o'jmitting the ignition condenser 4 in the circuit ofthegl'ow discharge tube 5. For thisreasonthe condenser 4 is shown in dottedlines in'Fig.'3. In

this case ffirst the glow discharge tube 1 is ignited under the effect of the ignition circuit 'when the voltage has 'beenconnected to the terminals l and 2, and thereafter also the glow 'discharge'tube 5 is ignited due tothe e'fiectof the voltage-increased by the voltage'drop across the choke 3 enem be alsoacross the choke 6.

The practically "tested values for thevarious components in the above described examples are 'thefollowing The choke 3 havingan inductance of 1.2.henr'ys, the choke 6 has an inductance of '0:5 henrya-nd the condenser 4 a capacity of 0.5 micr'ofarad;

"the'chok'e -8 has an inductance of 1.2henrys, the

sun directly to "the network terminals 1 and 2 The corresponding values of the components of this circuit may be I the following: 7,

The choke may have an inductance of 1.2

6 ihenr'ysjthe choke M an inductance of 0.25 henr-y andthe condenser I5 a capacityof 3 'micro'farads.

All the chokes included in the circuit arrangements as far described, or some of them, may be conveniently and easily formed into a structural unit by connecting the cir'cuits of the'various chokes to a common magnetic circuit.

In the usual so-called core construction of chokes, the cores of a common magnetic frame carry either the corresponding individual chokes or their separate coils, the magnetic frame being closed by means of end yokes. In the caseof a circuit arrangement with more than two glow discharge tubes the two magnet cores may be conveniently connectedalso by means of amiddle yoke.

The construction of such a choke is shown diagrammatically in Fig. 5,, in which the oncuitarrangement corresponds fully to that of Fig. 3 andtherefore the individual components are denoted by the same reference numerals. The combined choke is assembled in this case of separate component chokes 3, 6, 8 and 9 and ic'ompose'd of windings iii which are wound spirally, e. g. of an insulated iron strip. The various windings are assembled in two columns which are connected at each end by means of yoke l1 and I8, respectively.

The/choke construction shown in Fig. 5 is very advantageous especially "in respect of econemy of the material for making the chokes and also in respect of the advantageous mutual magnetic coupling 'of the various parts of the circuit during operation. In this way diilerent irregularities may be equalised, and if one of the glow discharge tubes becomes extinguished for any reason it is immediately ignited again. In this embodiment of the invention it is possible precisely to omit one ignition circuit for one of the glow discharge tubes, that is to omit the condenser 4, whereby the voltage drop across the component choke 3 and that across the component choke has well, are added to the supply voltage on the terminals I and 2 and thus produce an increased ignition voltcausing the glow discharge tube 5, which does not yet'glow or has been just extinguished, to be struck when the other discharge tube has "been previously ignited. The embodiment of the combined choke just described may used with advantage in a similarway for three parallelly connected glow di charge tubes in an arrangement corresponding to thatshown in Fig. 4. The common choke -may conveniently provided with a yoke in acentraliposition. v

In this connection Fig. '6 "shows diagra nniati Cally the use of a common choke for feeding in parallel .four glow discharge tubes 5, 1, 2i and 22 ffrom a single phase network I, 2. The lower part of this figure shows a pair of glow discharge tubes i with accessories, which pair corresponds to Fig. 5. In addition thereto second pair of glow discharge tubes 2! and 2 is rovided which may be connected up togethe h their respective circuit elements to form igement quite similar to that of the first'pa-ir 5 l, "and it of advantage to chose the the elements as to secure in the ignition circuit an increase the t'oltage under the effect of iffei ht harmonics. its upper part a .figw a. ehews s mewhat .I lied circuit arrangement for the second pal-r ef glow discharge tubes 2| and 22.

a The component chokes -23 and 24 correspond quiet and continuous burning of the discharge tubes is not an absolutely necessary require- 'ment.

"The effect of the condensers 26, 2'! and 28 is quite the same as that of the condensers s, H] and H of the lower pair of glow discharge tubes 5 and '4. Similarly as in the foregoing circuit arrangement, the condensers ti and 26, shown in dotted lines, may be omitted, and then all the four glow discharge tubes will be struck by the ignition circuits containing the condensers II and Ed. The condensers IE] and 21 serve for compensation and their operation has been explainedin the foregoing description.

Fig. Gshows the end yokes, l1 and it, which correspond to the yokes denoted by the same references in Fig. 5, and a middle yoke 29, the construction of which is adapted to its function. The use of such a middle yoke represents a relatively great saving of material as compared with the use of two independent chokes corresponding to a separate feeding of the two pairs of glow discharge tubes, the pair Eand on the one hand, and the pair 2i and 22 on the other hand. The middle yoke 29 may be made weaker than the edge yokes I1 and I8.

Referring now to the values of the circuit elements in the arrangement shown in Fig. 6 each pair of windings of the lower half of the chokes has a self inductance of 0.2 henry and the corresponding condenser d has a capacity of 3 microfarads, the condenser is has a capacity of 4 microfarads and the condenser H has a capacity of 3 microfarads. In the upper half of the chokes each pair of windings has a self inductance of 0.3 henry, and the corresponding condenser 26 has a capacity of 2 microfarads, the condenser 2'1 has a capacity of 4 microfarads and the condenser 23 has a capacity of 3 microfarads. Of course, as it has been stated in the foregoing description, the condenser 1i, and if desired also the condenser 26, may be omitted.

By the use in accordance with the present invention of combined chokes assembled of component chokes, first of all a large amount of material is saved, as previously stated, which material would be required otherwise for the construction of the individual chokes separately from oneanother. A further advantage in the present case consists in the provision of a common magnetic coupling for all the component chokes, such a coupling having a favourable effect on the compensation of any irregularities which may appear during the operation of the glow discharge tubes.

The advantage of using ferro-magnetic windings for the combined chokes appears from the a part of the description relative to Figs. 5 and 6 of the drawings. Apart from the possibility of substituting ordinary iron for the more valuable copper, an exceedingly simple construction,

which is very advantageous from the standpoint of manufacture and is much superior to the constructions as hitherto used, is secured for such chokes. Another important advantage consists in the possibility of obtaining combined chokes which have distinct electrical characteristics of any desired value, by assembling identical windings manufactured in mass production.

The examples described do not exhaust all the possibilities of utilisation of the invention. Still further possibilities exist consisting in various combinations of the elements referred to in the present specification.

What I claim is:

1. In combination with a single phase source of alternating current of a predetermined frequency, a circuit arrangement for starting and feeding first and second glow discharge tubes connected to said source via parallel circuits, the

circuit to each tube from said source including a starting inductance and a stabilizing inductance connected in series with the tube and a capacity connected in parallel with the tube through only one of said inductances, and one only of said tube circuits including a capacity connected in series with the tube to establish a phase difference between the current waves of the two tube circuits, the values of the starting inductance and parallelconnected capacity of each tube circuit being so chosen as to produce respectively therein substantially resonant conditions at different harmonics of the frequency of said source.

2. A circuit arrangement for a pair of glow discharge tubes as defined in claim 1 wherein the inductance capacity starting units of the two tube circuits become substantially resonant respectively at the second and third harmonics of the frequency of said alternating current source.

3. In combination with a single phase source of alternating current of a predetermined frequency, a circuit arrangement for starting and feeding first and second glow discharge tubes connected to said source via parallel circuits, the circuit to said first tube from said source including a starting inductance and a stabilizing inductance connected in series with the tube, and the circuit to said second tube from said source including a starting inductance and a stabilizing inductance and also the starting inductance only included in said first tube circuit connected in series with the second tube, and a capacity connected in parallel with the second tube through only one of the said inductances series connected with said second tube, the capacity and starting inductances in the circuit of said second tube having such a value as to establish in said circuit a substantially resonant condition, and one only of said tube circuits also including a second capacity connected in series with the tube to establish a phase difference between the current waves of the two tube circuits. 7

4. A circuit arrangement for a pair of glow discharge tubes as defined in claim 3 wherein the circuit of said first tube includes only said starting and stabilizing inductances.

5. A circuit arrangement for a pair of glow discharge tubes as defined in claim 3 wherein all the said inductances are constituted respectively by windings distributed on two columns of a common choke, the winding appertaining to the starting inductance in the circuit of said first tube being arranged on one of said columns, and the three windings appertaining respectively to the remaining three inductances are arranged on the other of said columns. 7

6. An arrangement for two pairs of glow discharge tube circuits with the tube circuits of each pair arranged in accordance with claim 3 wherein all of the said inductances of the four lamp circuits are constituted respectively by windings distributed on two columns of a common choke, the ends of said columns being magnetically connected by end yokes and their mid-parts bein magnetically connected by a middle yoke, the two windings appertaining respectively to the starting inductances in the said first tube circuit of each pair being arranged on one of said columns at opposite sides of said middle yoke, and the three windings appertaining respectively to the remaining three inductances in the tube circuits of each pair being arranged on the other of said columns at opposite sides of said middle yoke.

7 A circuit arrangement for two pairs of glow FRANTISEK LEHMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 15 2,195,114 McCarthy Mar. 26, 1940 2,373,402 Lecorguillier Apr. 10, 1945 2,404,254 Short July 16, 1946

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