US1551524A - Electric lamp - Google Patents

Description

f A 1551524 E.. FRlEDERlCH ELsc'rnxq LAMP Aug. Z5, 1925.

nud hug. 50, 1921 .'b'y an inertgas or vapor,'and so Patented Aug. 25, ,1925.

UNITED STATES PATENToFFlcE.

-ERNST FRIEDERIGH, 0F BERLIN, GERMANY, ASSIGNOR, BYIIESNE ASSIGNMENTS, T0. GENERAL ELECTRIC COMYANY, 0F SICHENECTADY, NEW YOP-K, A CORPORATION 0F New YORK.

sanering LAMP.

Appucauan med August so, mai. "smal no. 496,942.

(ensures ummarnarnovrsxous or rma ser or man s, m1, 41 sur. L., ma.)

To all whom it may concern: Y

Be it known that I, ERNST FRIEDERICH, a

citizen of Germany, residing at Berlin, Ger

many, have invented certain new and useful Improvements in Electric Lamps (for which applications for patents have been ledin Germany, June 3, 1914, A26055, VIH/21 f, and August 13, .1914, A215383, VIII/2U; Hungary, May 22, 1915, and August 13, 1915;` Switzerland, May 22, 1915, and August 10, 1915; Netherlands, May-28, 1921, and August 10, v1915; Sweden, June 2, 1915,' and August 11, 1915;, Great Britain, June 3,1915, and August 1,2, .1915; Japan, March 4, 1920,and March 11, '1920; Austria, May 31, 1915, vand'August 23, 1915), of ,which the following is a specification.

The' present invention relatesfto electric lighting, and more particularly'to a lamp in which an are is operated in an enclosed envelope between electrodes of highly fractory metal, such as tungsten-surrounded PI'OPQI" tioned -that they will be heated descence. v- One ofthe objects ofmy invention is to provide means for'starting the arc in a lamp of this nature. A further object of my invention is to lprovidean improved arrangement of electrodes whereby a higher operating efficiency, a. longer life and a better lightdistribution may be obtained.

The novel features; omy invention with further objects and vantages will .best be understood by .reference to the-following description taken in connection with the ae- -lrcompanying drawing in which. Fig. 1 illustrates a lamp equipped with one of my imm proved starting devices; Fig. 2 shows -a modification thereof inwhich two vsets of electrodes are Aconnected in series and in which electrodes of an improved formi are employed;-v Fig. 3 is a view of the supportf ing arrangement for the electrodes o the lamp shown in Fig. 2 taken at a right angle tothe view indicated in Fig. 2; Fig. 4 is a bottom v iew of'the arrangement used `in Fig. 2`for starting the lamp; and Fig. 5is an enlarged detail view of one pair of the `electrodes of the lamp shown in Fig..`2 with 'the starting conductor which bridges them when the lamp is not'in operation. Fig; 6 is a` wiring diagram of the arrangementshown 1n Fig. 2.

the arc in lamps of th1s nature because of the fact that a higher voltage is required to bridge the gap between the electrodes to start the are than is required forits normal removlng an intermediate oonductin mem. 'ber which. bridges the electrodes w en the lamp is not in operation, provided` a suit-- 'able' material is used for this bridging mem- Diiculty has been experienced in starting 55 operation. Neither can the arc'bereadily 60 l ber. .Among the materials -which ma -be used for this purpose are metals which v materials which are more suitable are oxides which are good Aconductors when cold, such iii uranium-oxide, vanadium oxide and the 1 e.

The method of operationof vmy-improved VQ 70 a higher electronic emission than tungsten starting device may' perhaps be explained 80- as follows:

0f the conductive bridging member some portion, though very small, will cling to the refractlf electrodes by the mechanical pressure of the contact or by fritting as soon as the`part which is in contact becomes heated byits resistance when the circuit is closed. At these particles the arc starts and easily-persists in consequence of the suitability of the material. These small particles 9 of course are vaporized rapidly but in the meantime the temperature` of the electrodes has risen so rrapidly that they themselves now maintain the arc continuously and reliably. With respect to the conducting oxides it is possible that the suitability of such materials may for myY purpose be explained b the well-known phenomenon thati drop across the electrodes. The conductive uranium oxide having a formula ljOz'fis particularly well adaptedv forthezprgsent pur- 'such 'exi esas soon asthey become heated emit large -numbers of electrons and on this 10 'account reduce to a'large extent the'v voltage in comparison with that of the anode has' still another advantage. In lighting lamps ol' this nature it is necessary that the cathode shall tlrst be heated to a high temperature. It the 'cathode is -of small area inI compari' on with the anode-and the lamp is to be' started by bringing the electrodesv in contact and withdrawing them,'the cathode will become more highly heated at the contact point by reason of"its small size and higher resistance, and on this account it 1vbecomes possible to start the arc by merely bringing the electrodes together and separating them. This advantage is also present when the lamp is lighted by the use of an auxiliary electrode or if it is to be lighted by removing a bridging rmember as heretofore described.

Itwill o `eurse be understood that the methode starting which I have described is in no way limited to spherical electrodes as other forms of electrodes, helical for exalnl'ple, may equally well be employed. It wi also be apparent that many variations -may be made in the particular arrangement used for withdrawing the bridging member from contact with the electrodes.v

' 35 of a. sealed envelope having thereinI electrodes of-highly refractoryv metal separated -by ashortgap and so proportioned as to be .heated to mcandescence by the passage of an arc between them, the surface area of the 40 electrode which serves as a cathode being" so small with respect to that of the anode that Iwhen the lainp is in operation the temperatur ofthe cathode is maintained higher than that of the anode.

-2. An electric lamp comprising a sealed envel e having therein spherical electrodes of hig ly refractory meta'l separated by a` short gap and so proportioned as to be heated to incandescence by the passage of L an arc between them, the electrode which 'serves as a cathode being larger than the one which serves as anode whereby when the lamp is in operation the temperature of the cathode is maintained' higher than that of the anode.

3. An electric lamp comprising a sealed envelope having therein spherical electrodes of highly refractory metal' separated by a short gap and so proportioned as to he 80 heated to incandescence by the passage ot an arc between them, vthe electrode which serves as a cathode being larger than the one-which serves as anode,. whereby when the lamp is in operation the temperature-of the cathode is maintained higher than that of the`anode, and means forstarting an arc between said electrodes comprising a body electrodes when the lamp is, not in operation and which is automatically withdrawn from -said bridging position when current starts toflow in said lamp.

il. In an arc lamp a sealed envelope, a`

pair of electrodes of solid refractory metal adapted to be connected to a source ot current, said electrodes separated by a gap, a solid arc starting element bridging the gap and being in contact with the tw'o electrodes before the arc is established and electromagnetic Ameans for separating the element from the electrodes for establishing the arc between the electrodes andlor holding the element from across the gap as long as the arc isv established, the surface of said element having a higher electronic emission than the metal at the same temperature whereby the arc -may be established at a `ot conducting material which bridges said y lower voltage than when the electrodes are brought into contact directly.

5.In an arc lamp asealed'envelope, a pair of electrodes of refractory solid metal adapted to be connected to a source of current, said electrodes separated by a gap, an arc starting element forming Contact with the electrodes and bridging the gap, electromagnetic means for starting 'the arc between the electrodes by withdrawing the element from across the electrodes and formaintaining the element out of engagement with the electrodes while the arc is in operation. said element being inthe form of .a solid the surface of which is adapted to yield an electronic emission sufficient to start the arc between the electrode at a lower voltage than if the electrodes are brought into contact directly and separated, said envelope containing a gas which is inert with respect to the electrode.

6.' In an arc lamp a sealedenvelope, a. no

pair of electrodes of tungsten adapted to be connected to a source of current. said electrodes separatedvby a gap, asolidvarc starting element bridging the gap and being in contact ywith the two electrodes before the arc is established and elcctromagnetic'means for separating the element from the electrodes for establishing the are between the electrodes and for holding the clement from across the gap as long as the arc is established.v the surface of said element having a higher electronic emission than the metal at the same .temperature whereby the, arc' may be established at n .lower voltage than when the electrodes are brought into conl tact directly.

7. In. an arc lamp a sealedenvelope, a pair otfelectrodes of tungsten adapted to beconnected to a source of current, said electrodes separated by a gap, an arc starting element forming contact with the elec- ERNST vogage chan mt@ com/act

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