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Publication numberUS2153009 A
Publication typeGrant
Publication dateApr 4, 1939
Filing dateAug 28, 1936
Priority dateSep 10, 1935
Also published asDE887668C
Publication numberUS 2153009 A, US 2153009A, US-A-2153009, US2153009 A, US2153009A
InventorsWilliam J Scott
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electric discharge lamp
US 2153009 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

April 4, 1939 w SCOTT 2,153,009

ELECTRIC DISCHARGE LAMP Filed Aug. 28, 1956 INVENTOR WiHiam Joseph Scott Patented Apr. .4, 1939 I PATENT. OFFICE ELECTRIC DISCHARGE LAMP Williani Scott, Rugby, England, assignor to General Electric Company, a corporation of New York 7 Application August 28, 1936, Serial No. 98,380 I Great Britain September 10, 1935 l 3Claims. (01.176-126) This invention relates to electric discharge lamps and more particularly to lamps having a filling of a metal vapor and a rare gas. In such lamps at high pressure the anode and cathode functions can with advantage be fulfilled by different parts of the electrode. Good electrodes for such lamps consist of a block porous fritted metal, such as molybdenum or tungsten, impregnated with electron emitting material.

A block of porous metal however is not easily outgassed when eddy current heating is employed.

The object of this invention is to provide an improved electrode for the above type of lamp and to that end it consists in making the electrode of a coned disc preferably of porous fritted tungsten fixed or moulded around an axial tungsten wire or bundle of wires which project through the apex of the cone into the are. When out gassing an electrode of such a shape by induction heating, the larger cross-section of the cone encloses many more lines of force than a block such as hitherto used and as the walls of the disc are thin, the distance from the centre of the material to the surface is much less than in a block so that out gassing can be carried out much more easily and thoroughly. The large area of the cone is further advantageous in that during the running up period the whole of the surface may act as the anode.

The accompanying drawing illustrates this invention Fig. 1 showing one form of electrode in section secured in the end of an envelope and Fig. 2 showing an alternative form in cross section. In Fig. 1, l represents an envelope of glass or other suitable material in the end of which is mounted an electrode consisting of a cone ll of porous fritted metal such as molybdenum or tungsten impregnated with an electron emitting material. This cone II is fixed to or moulded round a tungsten wire l2 which projects through the apex of the cone. The single wire l2 may be replaced by a twisted bundle of small wires if desired. The end of the wire l2 may be made smooth or it may be enlarged by securing thereto appropriate half cycle.

operation of the lamp and provide visible light.

Alternatively the end of the tungsten wire or wires may be are welded and rounded over as shown at I 4 in Fig. 2. The disc is wholly or partly anysuitable way and may-be heat treated for instance, by firing in hydrogen before sealing it into the lamp. The axial wire I! is either sealed directly through the envelope in, or is joined to the inlead or to a heatinsulating wire loop joined to the sealed inlead, when desired. Impregnation and outgassing are facilitated by making the disc thin and by using a minimum weight of electrode material. The conical shape assures accurate centering of the are at the electrode. Athigh pressures the projecting tungsten wire or wires l3 fulfils the anode function and the outer cone surface the cathode function. At low pressures and on starting practically the whole electrode fulfils both functions thus minimizing electrode disintegration.

In order to improve the mechanical strength of the fritted mass and its adhesion to the axial wire or wires the tungsten may have a minute percentage of a metal such as nickel added to it. This can be done, for example, by adding the nickel as a powder, as a solution of one of its compounds, as a colloidal, suspension, or by ball milling the tungsten powder in a nickel container before moulding, when desired. It is important that the quantity of nickel be kept low as otherwise it is apt to evaporate and blacken the tube walls.

This addition of nickel can under certain conditions serve to improve the electrode electron emission. For starting purposes part of the inner cone surface may be covered with a layer of nickel l5 shown in Fig. 1 which is in turn coated with electron emitting material. This nickel may be a sheet or gauze washer or may be sprayed on to the tungsten.

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

1. An electrode for an electric discharge lamp device having electrodes and electrode leads sealed therein, said electrode comprising a coned disc of porous tungsten secured at its apex to a tungsten electrode lead on which said coned disc is axially mounted, the apex of said coned disc being'in closer proximity to the opposite electrode than the base thereof, said lead extending through said coned disc and projecting through the apex thereof, the end of said wire forming a rounded projection.

2. An electrode for an electric discharge lamp device having electrodes and electrode leads sealed therein, said electrode comprising a coned disc of porous, fritted tungsten having an admixture of nickel therein and a material of high electron emissivity characteristics associated therewith,

said coned disc and projecting through the apex thereof,

3. An electrode for an electric discharge lamp device having electrodes and electrode leads sealed therein, said electrode comprising a coned disc oi.

porous, fritted tungsten having an admixture of nickel therein and being secured at its apex to an electrode lead, the apex of said coned disc being in closer proximity to the opposite electrode than the base thereof, said lead extending through said coned disc and projecting through the apex thereof.

WILLIAM J. SCO'II.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2562887 *Jan 4, 1945Aug 7, 1951Westinghouse Electric CorpVapor lamp and system
US2622409 *Jul 26, 1946Dec 23, 1952Inst Divi Thomae FoundationUltraviolet light source and circuit for refrigerator cabinets
US2670451 *Jan 12, 1950Feb 23, 1954Westinghouse Electric CorpShort arc high-pressure vapor discharge lamp
US2716713 *Mar 22, 1950Aug 30, 1955Gen ElectricCold electrode pulse lamp structure
US2720474 *Sep 13, 1952Oct 11, 1955Raytheon Mfg CoCoated electrodes for electron discharge devices
US2725495 *Jun 4, 1951Nov 29, 1955Westinghouse Electric CorpDischarge lamp
US5256935 *Aug 28, 1991Oct 26, 1993Toshiba Lighting & Technology CorporationLow pressure mercury vapor discharge lamp having cold cathode
DE1088612B *Dec 11, 1958Sep 8, 1960British Thomson Houston Co LtdVerfahren zur Herstellung einer Rohelektrode fuer Elektroden von Hochdruckentladungslampen
EP0441387A2 *Feb 7, 1991Aug 14, 1991TOSHIBA LIGHTING & TECHNOLOGY CORPORATIONLow pressure gas discharge lamp
EP0473164A2 *Aug 29, 1991Mar 4, 1992TOSHIBA LIGHTING & TECHNOLOGY CORPORATIONLow pressure mercury vapor discharge lamp having cold cathode
Classifications
U.S. Classification313/331, 313/355, 313/627, 313/351, 313/346.0DC, 313/325, 313/326, 427/77
International ClassificationH01J61/073, H01J61/06, H01J29/10, H01J31/08, H01J29/43, H01J29/38, H01J31/50
Cooperative ClassificationH01J61/0732, H01J2231/50026, H01J31/50, H01J2231/50063, H01J29/38, H01J29/43
European ClassificationH01J61/073A, H01J31/50, H01J29/43, H01J29/38