US2305907A - Self-ballasted arc lamp - Google Patents

Description

INVENTOR, G'Eofm: 5. Siwa-nerf.l BY ATTORNEYS HW/Mil. A c.

DCC- 22, 1942- G. sfsPERTl SELF BALLASTED ARC LAMP Filed May 5, 1941 UNITED STATE Patented Dec. 22, 1942 asoman Asiam;nilLLAs'rnn Ano George S.`Sperti, Fort Mitchell, K y.,anignor to' w Institutum Divi Tlxomac` Foundation,

Cincinnati, 01110, a corporation .of Ohio ino., t

aspiration Moy 5, 1941, soi-iol Norsslsc (on 11s-i) iolaimi.

My invention relates to' lampsof atype in -which an arc is struck between `electrodes in an envelope.y containingy rareiled and ionized gas. Suchlamps are useful lfor afwide varietyof purposes. For example, when the envelope conwavelengths of light, such .1axnpsare. useful as tains mercury and is `pervious tothe shorter.A

. Way.' ,the[advantages ofwhich the ensuing description;

4 iliieciiji'catlo'n.` I accomplishby that certain combisources DI ultra-violet radiations. Employed in connection with fluorescent substances,'thelamps are usefu1 as illuminants. The fleldfof .utilitypi the lamps, the nature of the arc (whether low pressure o r high pressure), the nature of the sub-,

stance controlling jthewavelength ofthe radiation., and whether the envelopeis pervious or impervious to ultra-[violet light or has a 'filtering action on theY light produced dol not constitute a limitation on my invention, -and will not hereinafter be discussed.

, The f chieibject of my invention is the soinr tion of the problemof .providing a self-ballasted Vlamp ofthe,` generalcharacter referred to above..

The problem itself is not new. There is-need, for an -arc devicewhich dici not. require externall ballast-.ing inpedances. such' as resistances, chokes or transformers, lnoi' start- ,ing devices. Anexemplar offan ideal structure .nation of elements of-whichl I shall vnow describe the'aforesaid'exemplary embodiment. Reference 1 Figure' 1. is a vertical sectional' view"of the exemplary lamp. j 1

Figs.'2 and Bare diagrams` showing the operrig.' i is, o; kperspectiva. view of the'thire oleowould befa lamp ofthe ,typeV referred to, genkind, itbeing understood., however,that the' shape of the envelope, the disposition-oitheparts. the

nature ofthe .base andthe like may all be widely Mvaried to provide lamps for 'different `eltls of use without departing from thel invention .fas expressed `in the appended claims.

erallyresembling an ordinary incandescent lamp, and capable oi' the` saine indiscriminate use in -any outlet1oitherequired voltage.` I shall denscribe Amy invention in any embodiment of this Brieiiy, in the practice of myinvention 1 provide,l in'an envelope with a suitable-atmosphere,

1a pair oi' alternate. electrodes, which'I 'willrefer toas electrodes A andB. electrodes are eachconnecteddirectly to one ofthe linetermi- Across the'lineterminals I also provide a doubleiimpedance, conveniently a resistance in -thef'orm of'a mament v or lamentsf. The i'mpedanceis double in .the sense not more thansilbstantially half f itv'ls required t0 bal- 305 lastthelaire.-V vBlihstalliiiilly 'at the effective midimpedance point of. this element 1 provide an electrode C, equipped with electron emitting Much work been done'on seli-baliasted n lamps land workable structures have been proced. But such structures have had certain de-v ects,l the elimination of which form ancillary objects of this invention. Such structures have in general been complicated in form, expensive to produce, frequently fragile and of limited life, and have often involved dual use of elements with accelerated destructionthereon e. g., the use of iilaments both as incandescent elements and as arc electrodes. Moreover the exigencies of the design and manufacture of such devices has frequently been such that the electrode elements could not be properly placed to give an arc of the required length or at a position in the envelope suitable for optimum radiation of the emitted light. l

means. These elements, together with supportingmeans for the parts and shielding lmeans for 1 the niainentsjwhere required, constitute the fundamental operatingv elements of my'` structure.

Their mode of 'coaction vtvilljbe set forth hereinau.e r. l..

inthe exemplary structure shown in Fig. el, I is 'an' envelope of suitable translucent substance and containing the desired atmosphere under the 'desired pressure.

2 and 3 are the line terminals passingthrougha press 4 into the envelope. A of' alternate -arc electrodes A and B are connected to the line terminals. The press is also shown as supporting refractory shielding tubes 5 and 6 of glass, ceramic, quartz or the like. The impedance mentioned above is shown as a continuous filament 1 disposed in substantial U shape. and having its legs encased in and shielded by the tubes 5 and 6. The ends oi the illament are connected respectively to the line terminals 2 and 3 as at 9 and Il.

Intermediate the ends ot the illament, and Preferably at or near the center or resistance It is also an object of my invention to provide I provide an electrode C. There should be an electron emissive substance in connection with this electrode: and the form of the structure which I prefer to use is shown in Fig. 4. In practice I provide a ceramic block II perforated longitudinally as shown. The filament 1 is associated with the block by being laced forwardly and backwardly through the holes, also as shown, so that the passage of current through the filament will heat the block and in turn a metallic sleeve I2 on it. The sleeve I2 is coated with an electron emissive substance such as a refractory oxide. The sleeve is connected to the filament 'I at or near its mid-impedance point by a connection I3. The electrode may be supported from one of the tubes 5 or 'I by a bar I4 or in some other suitable way. Other electrode structures for the electrode C may be employed; but it should be with this electrode .that the electronemissive substance is associated, for reasons which will be clear hereinafter.

The manner of operation of the device i-s shown in Figs. 2 and .3. The filament heats the electrode C causing the electron-emissive substance associated with it to give off electrons. While the electrode C is located approximately at the mid-impedance point of the filament 1, it will nevertheless (as shown in Fig. 2) be negative with respect to electrode A on one alternation of an alternating exciting current. Under these circumstances an arc will strike between electrode` C and electrode A. The portion of the iliament lying between C and B will act as ballast for the arc so struck, and the other portion of the illament will be effectively short circuited by the arc. It is true that under thesecircumstances electrode C will be positive with respect to electrode B; but no arc will be struck between these two electrodes, for the reason that the stream of electrons causes the arc lto pass between electrode C and the electrode which is electro-positive with respect to it. On lthe other half of the alternating cycle, the conditions are reversed, and, as shown in Fig. 3 the arc will pass between electrode C and electrode B which is now electropositive with respect to it. The portion of the lament lying between A and C will act as ballast for the arc. This alternating action will continue, changing with alternations of the current. First one section of the lament and then the other will actas ballast for the arc, and this is why I have referred to the impedance 1 as a double impedance.

My lamp is, however, operable on direct current as will be clear. Alter the atmosphere in the envelope has become sumciently ionized, the arc will strike and pass continuously from electrode C to either electrode A or electrode B depending upon which is electro-positive withr respect to C, and this in turn will depend on the way in which leads 2 and l are connected to the power terminals.

l'he tubes l and i protect the illament sections and prevent the striking of an arc to any Portion o! the filament. It will be understood that the lamp will be provided with a suitable base, not shown: and that the placement and disposition of the parts can be varied without departing from the spirit of my invention.

Having thus described my invention, what I clalin;s as new and desire to secure by Letters Paten t 1. In a light source of the character described. an envelope. a press in said envelope, a pair of conductors passing through said press, elongated insulative tubing means engaged with and supported by said press and extending a substantial distance therefrom, a pair of filamentary resistance means connected to said lead-in wires and extending the length of said tubing means, said resistances being connected together beyond the termination oi' said tubing means and connected to a thermionic cathode, and a pair of electrodes located adjacent said press and connected respectively with said lead-in wires, each of said resistance means having sumcient resistivity to ballast an arc struck betweensai-d thermionic cathv ode and one of said electrodes.

2. The structure claimed in claim said insulative tubing means consists of two interspaced tubes of tran-slucent substance, eachr ed with respect to said sleeve as to heat it,A therel being an electrical connection between said sleeve and said filament. 'v

4. Thev structure claimed in claim 1 4wherein said insulative tubing means consists oi' 'two interspaced tubes of translucent substance, each containing one of said resistance means. and in which said thermionic cathode means is supported by one of said tubes, and in which said thermionic cathode means comprises a metalV sleeve coated with electron emissive substance. said resistance means comprising in eilectr a continuous resistive iilamentga` portion '-o'f which is so located with respect to said sleeve as to `heat it. I

there being anV electricalconnection between said sleeve and said iilament. and in which said elec- -trodes are supported on wires passing through said press, vthere being electrical connections between said wires and said lead-in wires.

y 1 GEORGE S. SPER'I'I.

1 wher/ein

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