US2481468A - Luminescent tube system and apparatus - Google Patents

Description

P 1949- J. H. BRIDGES 2,481,468

LUM-INESCENT TUBE SYSTEM AND APPARATUS Original Filed Aug. 12, 1943 2 Sheets-Sheet l V6 Samm Z X f I Sept. 6, 1949. J. H. BRIDGES 2,481,463

LUMINESCENT TUBE SYSTEM AND APPARATUS Originai Filed Aug. 12, 1943 2 Sheets-Sheet 2 gluvucmlo o of my invention, while;

Patented Sept. 6, 1949 LUMINESCENT TUBE'SYSTEM AND APPARATUS I John Herold Bridges, New York, N. Y., assignor to National Inventions Corporation, a corporation of New Jersey 7 Original application AugustlZ, 1943, SeriabNo. 498,344. Divided and this application October 1, 1946, Serial N0. 700,427 I Claims. (Cl. 315258) My application is a division of my copending application 498,344 of August 12, 1943, entitled Luminescent tube system and apparatus, now patent 2,436,951 of March 2, 1948, which in turn is a continuation-in-part of my copending application Ser. No. 469,365 of December 1'7, 1942, entitled Luminescent tube system and apparatus, and the invention relates in general to electric lighting systems and more especially concerns luminescent tube systems of illumination and apparatus therein. A

The object of my invention is the provision of a safe, reliable and highly practical gaseous electric discharge tube lighting system including a transformer source of electrical energy. and a plurality of tubes, which system is characterized by thoroughly satisfactory distribution of current to the tubes, by prompt and substantially simultaneous energization of the tubes, in which there is displayed but little'stroboscopic effect,

and which during operation has an exceedingly good power factor.

Another object of my invention is the provision of a gaseous electric discharge tube lighting system including a single-transformer source of electrical supply, which system is especially adapted for operating four up to as many as ten or more included light tubes, which achieves highly effective control over the tube-energizing current, and which is capable of continued operation in a safe and efficient manner despite failure of one or more of the plurality of included tubes.

Other objects will in part be obvious and in part pointed out hereinafter in connection with the following description taken in the light of the accompanying drawing,

In the accompanying drawing:

Figure 1 represents a gaseous electric discharge v tube lighting system including certain features Figure 2 is a diagram of the circuit employed in Figure 1 and additionally illustrates an advantageous grouping of tubes, and;

Figure 3 depicts a modified form of system in accordance with my invention.

As conducive to a clearer understanding of certain features of my invention, it may be noted at this point that gaseous electric discharge tube lighting systems are today in wide acceptance in various fields of illumination where incandescent lighting systems formerly were employed. There are numerous advantages which more than justify the employment of such lighting systems,

among these being characteristically low power consumption, coolness of operation, simplicity, sturdiness, improved dissemination of light,'and wide choice in the physical form of tube or tubes employed. A number of different physical dispositions or arrangements, moreover are possible in obtaining desired lighting effects as in factories, stores, and private homes ;-and the use of a variety of fillings such as fluorescent salts on phosphorus as active ingredients of the tubes enables the provision of a number of different colors of light. 1

Although," as pointed out, there has been wide acceptance of gaseous electric discharge. tube lighting, many of the systems present features which for practical reasons are'not wholly 'desirable:- Certain of the systems. essentially operate at low voltages and the tubes requirepreheating before initial starting is successfully achieved. These systems usually include a heater circuit and switchover mechanismwhich, as appurtenances, represent items of expense and a source of possible trouble in operation. A further objection 1 exists in that the tubes flicker during the preheating periodand considerable delay occurs before steady operation is achieved. Hot cathode tube systems also are found to be unstable in operation at low temperatures, such as under temperature conditions frequently encountered in outdoor use.

In certain heretofore known gaseous electric discharge tube systems of the multi-tube type, failure of one or more of the included tubes disrupts further operation until full and proper replacement of the worn out tubes is made. This latter objection is notable particularly in lighting systems which include a single transformer source of power and a plurality of tubes connected in series with each other and with the source of power. Such'systems-also require an increase in operating potential where the number; sizegor length of tubes is increased. On the other hand an upper limit on voltages is imposed by the Fire Underwriters'and thus the number of tubes employed as well as the dimensions thereof are sharply curtailed.

There too, are multi-tube systems wherein the tubes are connected in parallel across a source of electrical supply. In these systems lower operating potentials are made possible than should series connection of tubes be employed. There is, however, a tendency in such systems for an included tube of low starting potential or of high conductance to draw such a large part of the load current available that other included tubes either fail to start, or when they do start, draw such low currents that the current densities are wholly in- 3 V sufiicient to produce the desired brilliant glow. Still another objectionable feature, commonly termed stroboscopic efiect, is encountered in gas- 7 eyes, very discomforting, and in all is wholly desirable.

One of the outstanding objectsof' my ii iveii'ifion', Hi6

accordingly, is the provisionof a system if il mmr nation including a plurality of gaseous electric discharge tubes and a single transformer-source of electrical supply, in which system continuous operation of the tubes is notdisruptd by ,failureof one or several of the tuhes,l. in;which;all ftnbes promptly reach substantially full conductance r and brilliance and give a stable quality of illumination in and after starting, and in whioh a maximum length of tubing is safely and efliciently ape-rated. r

'sRei erring now :to the :general zipractiee {of invention, .1 provide .:an electrical illuminating system which comprises a step-sup transiiurmer, and :a plurality of gaseous ieleutric discharge tubes, advantageously eight to tender :or seven 'a's'ifiew as :fzoln :tubes individually I'conneeted ii-n maraliel with :a single :outpnit source of the "transformer. Each stuhe :cirmiitiiinclndes tan rz-imluctiue *reactance, and a gaseous electric discharge tube connected in series. 'oneznrim'one or Ithe'Jmbe icircuits, suchras alternatecir'ouits ..-additionally include a, condenser conrrectecl in the tube and iin'ductiue reactance. Eline inductive neactances tnrefierahlyia're ofrgsnch l typelas more fully :pointcd out-hereinafter;

illustratiue-iof the of any invention {in 11 :of the dnawmg there electric lighting system :con inrising ta shellatywe .step np itransrormm' in! having an imiernmieiportron I51 flanked on :opposite sidesebyl :C shaped V imiter dore' portions -12 .and its. 'Ilhe transformer core ima'de f paramagnetic material zsuch -;as or laminated iron. The zinnerpoitioniotfi'the owe mfera'bly has a 6ross-sectiona1learea subshan finally itwice' as iarge either mime iouter more iportions.

Inia'ss'embled condition thednansifomner none V maths mutually including .ilnrner oore'portioniil-li and respectively including outer more ipjortionsjwlsz and .:It will, L-hOW (IVBT FbE umderstood that-ideaspire certain aclya'n'tages being achieved through :the use @of a ,shell type transformer, a care w xtr ans former may instead be employed-in my.

'rl ig htingsystem. 1' V The :transfiomner shown includes la.

:ooil d4 'wvound tor ;example of heavy gauge wine V and disposed about :iin-ner aOOIB portion 114,. Sunjply ileads 46 fand ll extend :fromia-n alternating @curnent :source of electrical supply 158, .nonyendentlysoflw and 220 voltsrating toeppositeiends :01 the vtransformer primary coil .;A secondary coil l5 also disposed about inner coregportion Elli adjacent the l-primary (coil preferabl is wound nof small gauge wire and possesses .such number of turns as to have induced therein :ajdesined gstepped-up ,output voltage. At times .,I mount the" rprimary and secondary coils -.on .the transformer core .in superimposed rre'lationship so as so ,gain maximum advantage of compactness and isa ifings in materials. j M :While-it is within the province of my inven- ;tion to employ the transformer Ll]! .as an ror'difnary ltransformer with the primary and ,sec-

ondary windings related only inductively, I prefer to produce the necessary high output voltages by means of autotransformer connection. 7 Thus,

- 'ner :co're port'ion l l linking secondary coil l5 qretinningthrough outer core portions l2 and I*3to the primary winding. A high terminal voltage, zalccordingly, is induced in the transformer 2Q secondary winding, which winding for autotransiormer ,connection consists of lthe senies con-r nected coils l hand l5. 7 r .In .rthe ensuing half-cycle of {primary current the direction rof current is reviersediand flux coursestrom the ,primary windingsthrough inner co'reportion .Llto the left Eigure;1.- l'lhediiux,

in returning to V the primary {winding courses to the right along router core portions ill-and l3 -and tqlthe left back through inner core portion LL, The coils]; and \L5Lagainare linkedlimgne'tically'andlan electromotive forcenfnpposite direction ,to, that resulting from the first-half cycle of primary current-builds rupgacross the transformer seccndaryawinding. I 35, In. the illustrative embodiment o'f ,my viru en- V ltion I shown injEigure 1,, I emplo some eight;to 'ten' or "more, '{or as few ,as lfour fluorescent gas .d ischangetubesl; such .as fltubes' :Iil, T2, 113;,14, etcpgviconnected in parallel acnoss the autotransifonmer windings .of' transtormer Ill .One of the parallel tube circuits conveniently is traced the righthand side of secondarycoil 1L5 worked 22 to .terminal123; thence ,overleads 25 rand'zli, "through tube ialqng lead 721, Winding 'W,l -,of

mreacftur .Rl.,,and lead 28 over lead 2] .toi-terinitial 210; and thence elonglead 1.6,, across coil 11., lead [9 and coil 15 lbaok to the mintr be innin the ri hthand side of secondary ,coil I5 ouerIlead V 2,2 .to terminal 23,; lead condenser .Cw and 'lead 29 toitube T2, thron -h tube v.over lead 310, and across windingWl of'reac'tor R2; overleads .3 I .and 2] to terminalzq; and thence'alon-g lead Z5,.,.acro#ss Qoi1'. |'4,, ,lead1%,.ahd coil l5 back-tattle ,point of beginning. j

Tube T3 is energized inn .circuittitaqed from the righthand .side' of coil 15.0w! lead 22 to terminal 23,; thence lover leads .25 and 32, through tube across lead 33,, windingW3 ..of reactor R3, and lead'3'4; along leadfl] lto iterm'inal 2 and across lead 1.6. can 1.4, dead L'S'andcoil "l5'bagfiki0fihefi0inhof beginning. r

Another tube circuit, beg nning .at the ri ht 5 handend .of coil ll 5', extends over lead .22., through terminal '23 across lead i2 ,,vcondenser C, and

7 actors may .be connectedlacross .lea'dsQZJ and 124 7 ,so .as to .Iorm parallel .condensiye circuits with Y the tran former, nutput winding, and/prim in the present embodiment of my invention, I 7

Assume, for

TA second tube circuit "is'traced' beginning =,at

parallel across leads 2I and 25 so as not td include the condenser C. The tubes of the entire system provided advantageously are grouped or banked such as in pairs of adjacent or contiguous tubes with one tube only of each pair being in a condensive circuit. Other groupings may be used in which at least one tube in condensive circuit is present, even to the extent of all the tubes of the system being in one bank. Each tube circuit may be closed by a separate switch (not shown) or each bank may be controlled through a separate switch, as pointed out more particularly hereinafter with respect to the embodiment illustrated in Figure 3. Where the-tubes of the entire system form but one bank, I find advantage in placing alternate tubes in condensive circuits and controlling pairs of adjacent tubes with corresponding switches.

Through the use of a reactor in each oithe tube circuits, any tendency for one circuit to draw such high currents that the current density in the remaining circuits is insufiicient to produce light at-full brilliance, is substantially dispelled. The additional use of a condenser in several of the tube circuits lends an improved power factor to the entire lighting system. Tubes in the condensive circuits, moreover, operate in out of phase relationship with the tubes in the remaining circuits so as to maintain stroboscopic effect of light emitted from the system as a whole at a minimum. l

The lighting system is highly efiicient in operation and has particular utility where some eight or ten or more gaseous electric discharge tubes, or even as few as four of such tubes, of substantial length, are to be energized. The tubes employed are found to have long life due at 'least partially to the excellent control over energizing current maintained in the system. With an increased number of tubes in the system, initial installation costs are readily justified, especially When account is given to cost of installing and maintaining a like number of tubes in accordance with the prior art. By operating on increased number of tubes with a single transformer, as for example, up to '70 inches or more of 25 millimeter tubing, core losses in the system decreases, and operational efiiciency increases all the more. The characteristic reduction in stroboscopic effect achieved is enjoyed at full maximum by grouping the tubes so as to obtain blended light from the tubes operating in diiferent phase relationship. One advantageous grouping of tubes is shown diagrammati cally in Figure 2 of the drawing where-paired tubes in adjacent side by side relationship are connected as in Figure 1 for out of phase operation.

I prefer to use reactors in my lighting system which display little, if any, current controlling action when no-load conditions prevail, but which instantly interpose high reactances when the tube loads are energized and high current begins to flow.

A reactor, illustrative of the type just mentioned, is indicated generally in Figure 1 by reference character RI. The embodiment shown includes a shell-type core comprising a longitudinal inner core portion 38 having a reactor winding W I thereon and terminating at one end in oppositely extending transverse portions El, E2. Outer core portions 39 and 40 extend from the other end of inner core portion 38 around winding WI to points just short of the ends of extensions EI, E2, respectively. The outer core 'portions thus form magnetic paths through andreluctance. I prefer to make core portions 33 and 40 of like cross-section and the inner core portion approximately twice as large in cross section as either of the outer core portions. I also prefer to maintain a symmetrical disposi-- tion of all component core legs in the reactor assembly and equal calibration of air-gaps so as to obtain balanced magnetic conditions in the several magneticpaths of the reactor.

Similarly, reactors R2, R3 and R4 comprise inner core portions 38a, 38b and 380, respective-- ly, and corresponding laterally extending end portions E3, E4; E5, E6; and E1, E8. Reactor windingsW2, W3, W4 are mounted on respective inner core portions of the reactors. Outer core portions 3311,4011; 39b, 40b; 39c, 40c extending from opposite sides'of the lefthand ends'of the inner core portions, form air-gaps G3, G4; G5, G6, G1, G8 of calibrated reluctance with the laterally extending end portions.

In the present embodiment the reactors RIR.4 are designed for the same or similar tube loads, and one substantially alike in construction. It will be understood, however, that the reactors may possess different current limiting qualities depending, for example, upon the tube loads to be energized in the individual parallel circuits. The reactors also may to good advantage be of the core-type having single magnetic circuits interrupted by fan included air-gap of calibrated reluctance.

When the primary circuit of transformer I0, including alternating current source'of supply I8, lead I6, primary winding I4 and lead I1, is closed by means of a suitable switch (not shown) an induced voltage is impressed across the transformer output terminals 20, 23. This Voltage rises and falls at the same rate as does the current through the primary winding I4 and a tendency exists to develop a flux in the magnetic paths or circuits of the reactor cores. The direction of this flux is such as to induce in the coils WI, W2, W3 and W4 by self-inductance a voltage tending tooppose the provision of the included air-gaps GIG8 in the reactor cores the decrease in secondary voltage could reach important values and could appreciably retard the initial energization of the tubes. It is to nullify the effect of the self-induced voltage that the air-gaps 'GI-G8 are provided.

The tubes thus are energized readily, and a high current tends to flow through the system able quantity. A voltage, proportionate to the increased current, is induced in coils W IW4 to oppose further increase in current through the coils and to limit current flow through the tubes TI-T6.

It will, therefore, be seen that the reactors not only permit substantially full terminal voltage to be impressed across the corresponding tube loads at the time of starting, but seem to counteract the tendency for increasein current flow due to negative resistance characteristics of the tube loads or due to short-ci'rcuiting. The air-gaps in the reactor "magnetic circuits, 1 being of such arena 7 Fealibrated reluctance as to'prevent a. substantial amount of no-load flux from passing .thereacross and yet not being oflsuch high reluctance as to prevent .an appreciable amount of flux from crossing while the tubes are energized, are instru- 1 mental in maintaining the tube-energizing current within safe and properly controlled limits without impairment of the rapid starting characteristics of the tubes.

In Figure 3 of the drawing a somewhat-moth fled lighting system in accordance :with any invention is illustrated. The system is particularly "useful where a plurality of light sources controlled by separate switches areneeded as in auditorium or stage lighting or in illuminatinga number ofroom's of a building. Astep-u trans- :former All, such as an autotransformer having a primary winding 45 and a-secondary windin vinclucling coils 45 and'46,is employed for'energizi-ng some-eight to tenor more or even as few'as four gaseous electric discharge tubes, illustratively tubes T5--Tl0, connected in parallel with the transformer secondary winding. :The tubes preferably are arranged in'remotely spaced-or contiguous banks, each bank comprising two or more tubes, such as tubes T5-,-T6, v 'I"i-.T8, and T TH), is providedwith an energizin circuit which includes condenser and reactor means; and at" least oneother tube, as one of tubes 'lfi, T'Land T9 is controlled :by reactor means without the and light emittedfrom the energized is 'rthe "tubes display long life and thoroughly satis- -factorylig'ht-emissive qualities. 7 I; also prefer to employ tubes lined with a fluorescentcoatingof phosphor and filled with a gas such as neon, ar-' gon, helium, or the-like, with or ithout mercury Va pOI'w In my lighting system the particular parallel network .distributes'higher operating voltages for 7 given output voltage than doesthe conventional series connection heretofore'employed. The tubes strike extremely rapidly. and give off a steady light during operation even Where cold weather conditions prevail. I find'that in using a high secondary terminal voltage of, for example, :550

aid of a condenser. The tubesin each bank ad- 7 vantageousl are grouped together as inside vby side relationship illus'trativelyin a fixture having a suitable reflector,land are controlled by switch means, as for eXample-oneof the switches 48, '52 or. 56, independently of tubes in the other banks. v

In the embodimental systemillustratedin Figure 3, a secondary circuit may bevtracedfrom the righthand side of coil 46 over leads 4'! and 48 including switch 43a; lead 49 through reactorRE, lead a, tube T5 and leads 5| 44 to junction 43, and thence along lead 43' through autotransformer cells 45 and 46 back to the point or beginning. A parallel circuit is traced from the righthand side :of coil 46 across leads 4'! and ,48 includin switch 48a, lead 50, reactor Rilead Ellafthrough tube T6 and over lead v511b, through V condenser C5; leads 50c, 5| and 44 to junction 43, and along lead 4| and throughcoilsdli an 45 back to the point of beginning.

Likewise, parallel circuits are closed across the transformer output line Hill through lead 52 including switch 52a, first along lead 53, through reactor RLlead 53a, across tube T1 and through lead 531) and lead and, secondly, along lead 54b, through condenser C8 and across leads 54c and 55.

Similarly, two other parallel through lead 56, includin switch 55a, across lead 5'! and reactor R9, thence over lead 51a and through tube T9, and over leads 51b and 59; and; secondly, by Way of lead 56 including switch 56a,

lead '58 and reactor Rio, thence acrosslead 55a and tube T10, along lead 58b through condenser CW, and leads 58c and 59, respectively or 600 Volts, 'whichstill is Within the limits permitted by the FireUnderwriters for .autotransformer equipment, a: maximum length of is quite successfully energized. V I "Thus it will be seen that with my invention there is provided asystem of illumination in which the objects hereinbefor'e noted, together with many-thoroughly practical advantages/are successfully achieved. It will be seen that a.

single transformer output source is used insu-pe circuits areclosed across the transformer output leads 44, 41, first system, comprising in combination; a trainsformer including a primary winding connected -While the tubes in the several parallel circuits may be energized from the transformer secondary winding through individual switches in each en- 1 1 ergi-z-ing circuit, particular advantage is gained by energizing the tubes in banks including out of ,phase tubes through a switch ecorresponding to each bank as a whole. Thus when a particular switch isclosed, outof phase operationiis plying energizing current' to' a plurality of gaseous Zelectric discharge tubes in several parallel circuits, and that the voltage in the several circuits is'notonly high'but of substantially uniform value. It, will further be seen that the particular choke-condenser principles employed lend to prompt energization of the tubes, a

" steady character of illumination substantially free of stroboscopic' effect Where the tubes are closely grouped as hereinbefore described, and a hi hlysatis'factory power factor; and that the system .is adapted for operating a maximum length of included tubing and capableof safe,

continued operation despitethe failure of one :01

more of the several tubes.

r As manyvpossible embodiments may .be made of my invention and as many changes may be made the embodiments hereinbefore set forth, it

will be understood that all matter described herein or "shown in the accompanying drawing ,is to be interpreted as illustrative, and not in a limitingsense. f r .7 f

['I claim: r -i' r a '1. A gaseous-electric dischargetube lighting across a source of electrical supply, and a secondary winding step-up source of output supply; 7 at least two pairs of gaseous electricdischargze tubes connected .in.parallel1acircuits with said transformer secondary winding; current Elihu-ting iselfinductances having magnetic cores :and :included air-gaps included in each circuit of each 1 :pair of said parallel circuits; and individual condensers additionally included fin one of each pair ,of said circuits for eiT-ecting dizfiierzent phase operation for one tube cincuitrofeachspatr tubing 7 as compared with the remaining tube circuit of that pair,

2. A gaseous-electric discharge tube lighting system, comprising in combination; a transformer having an electrically continuous secondary winding; a plurality of tube banks individually including two gaseous electric discharge tubes; current limiting self-inductances having magnetic cores and included air-gaps included in circuit with each of the tubes; and individual condensers additionally included in circuit with one tube of each bank for effecting different phase operation for one tube of each bank as compared with another tube in the bank.

3. A gaseous-electric discharge tube lighting system, comprising in combination; a transformer having a secondary winding; two pairs of gaseous electric discharge tubes connected in parallel with said secondary winding and energized by said secondary winding through switches corresponding to the pairs; current-limiting selfinductances having magnetic cores with included air-gaps included in circuit with each of the tube circuits; and a condenser included in one tube circuit of each pair of tubes for reducing stroboscopic efiect.

4. A gaseous electric discharge tube lighting system, comprising in combination; a transformer having a shell-type core with a primary winding mounted on the central leg thereof and adapted to be connected across a source of supply, and a secondary winding also mounted on said central core leg; a pair of gaseous electric discharge tubes connected in parallel circuits with said transformer secondary winding; two current limiting self-inductances having magnetic cores and included air-gaps respectively connected in said parallel circuits; and an electrical condenser additionally included in one of said circuits for effecting different phase operation for one tube circuit as compared with the other tube circuit.

5. A gaseous electric discharge tube lighting system, comprising in combination; a transformer having a shell-type core with a primary winding mounted on the central leg thereof and adapted to be connected across a source of electrical supply, and a secondary winding also mounted on the central leg of said core and connected in auto-transformer relation with said primary winding; a pair of gaseous electric discharge tubes connected in parallel circuits with said transformer primary and secondary windings; two current limiting self-inductances having shell-type cores with included air-gaps respectively connected in said parallel circuits; and an electrical condenser additionally included in one of said circuits for effecting different phase operation for one tube circuit as compared with the other tube circuit.

JOHN HEROLD BRIDGES.

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

UNITED STATES PATENTS Number Name Date 2,050,135 Tour Aug. 4, 1936 2,298,935 Freeman Oct. 13, 1942

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