US1721384A - Electric lamp - Google Patents

Description

July 116, 32$.

G. R. FQNA mzmm ELECTRIC LAMP Filed May 51, 1928 emss WOOL A/ifi ammo/{me MA TE/P/ALS aoaron a. FONDA, onscnnnno'mnvflhvnw roan, assrenon no eannmr. anaemiccommmr, A. conroaarron or I NEW YORK.

nnnc'rnro Lair.

Application filed May 81,

The present invention relates to the construction of electric lamps and in particular to incandescent gas-filled lamps and its object is to provide a construction whereby destructive arcing in electric lamps is prevented upon the burn-out of the filament, or other light-giving body.

When large sized incandescent lamps are burned out by a severance of the filamentat some point, an arc tends to form between the two severed ends of the filament and this are tends to jump to the current supply wires and travel back to the base of the lamp, Where it may finally cause such overheating and fusion of the metal parts as to weld the burned out lamp into its socket.

In accordance with my invention I have provided arc-quenching materials in the path which the arc Would take from the burned-out filament to the base of the lamp. The volatilization of these materials causes such rise in the voltage necessary to sustain an arc, that the arc is extinguished before damage is done to the members surrounding the socket of the burned-out lamp.

My invention is illustrated by the accompanying drawing in which Fig. 1 is a side elevation of an incandescent lamp embodying my invention and Fig. 2 is an enlarged View partly in section of a portion of the filament mount.

Referring to the drawing, the lamp which is illustrated in Fig. 1 is of the gas-filled, concentrated filament type in which arcing is apt to be most destructive. Such a lamp comprises the usual sealed glass bulb 1 upon the stem 2 of which is affixed a pedestal 3 for holding the supports or anchor wires 4 of the incandescentfilament5. The endsof the filament 5 are connected to the current supply Wires 6, 7 which are sealed into the stem 2 and make electrical contact with external base, (not shown in the drawing). The filament 5 consisting of tungsten, or other suitable material, is of the usual closely coiled, zig-zag form which is supported at intermediate bent portions by the anchor Wires 4.

At some distance removed from the terminals of the filament a hollow section 8 is provided in the supply Wires, this section being supplied with arc-quenching material. I have found that certain salts, as for example, a nitrate of nickel, or copper, or sodium or barium, or the sulphates of copper or nickel to be suitable. Iron sulphate and barium sul- 1928. Serial No. 281,734.

phate also may be used in some cases. The sulphates of copper and nickel are particular- 1y favorable for use as they can withstand without decomposition a considerably higher temperature than the temperatures at which incandescent lamps are exhausted and operated. In general, suitable substances for the purposes of my invention are such which when heated by contact with an arc evolve gases, such as oxygen, or the oxides of sulphur or nitrogen, in which an arc is maintainable only at high voltage.

A small quantity of such arc-quenching material is placed in a tubular. container which is closed and connected at its ends by electr c welding or otherwise in such a Way that 1t forms a part of the current supply conductors without coming into immediate contact with the incandescent filament. I have ndicated small plugs of glass wool at opposite ends of the hollow container 8 but it Is not necessary in all cases that such plugs should be provided. The arc-quenching materlals may be placed into a small diameter tube which may then be swaged or otherwisemechanically reduced in diameter and finally cut up into suitable lengths which are made a part of the current-conveying conductors for the filaments.

hen a lamp, constructed as above described and illustrated, is burned out, an arc may continue to operate for some time between the severedends of the filament or may ump to the ends 9, 10 of the current conveyng conductors, particularly when the lam 1s operating in such position that these on s are located above the break in the filament. As'the filament leads usually consist of more readily fusible metal than the filament itself the arc will melt or volatilize the sections of the supply conductors intervening between the ends 9, 10 and one of the tubular containers 8. Upon reaching this tubular section the arc will volatilize the contained arcquenching material which will cause the arc to be extinguished.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. An electric lamp having current-conveying conductors and means operable by an are between said conductors for yielding gaseous materials having a quenching efi'ect upon said arc.

2. An incandescent lamp rovided with a gas-filled bulb, an incandgscent filament mounted therein, current-conveying conductors for said filament and a material capable of evolving an arc-quenching gas associated with at least one of said conductors.

3. A gas-filled incandescent filament lamp having current-conveying leads at least one of WhlCh contains an arc-quenching salt.

4. An incandescent filament lamp com rising a gas-filled container, a lighting ody therein, current-conveying leads therefor comprising a hollow member and a compound contained therein which has the property of producing conditions unfavorable to the operation of an are at the operating voltage of said lamp.

In witness whereof, I have hereunto set my hand this 29th day of Ma 1928.

GORT N R. FONDA.

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