US2019633A

US2019633A - Vapor electric device

Info

Publication number: US2019633A
Application number: US687602A
Authority: US
Inventors: Rentschler Harvey Clayton; Donald E Henry
Original assignee: Westinghouse Lamp Co
Current assignee: Westinghouse Lamp Co
Priority date: 1933-08-31
Filing date: 1933-08-31
Publication date: 1935-11-05
Anticipated expiration: 1952-11-05

Description

NV- 5, v1935- H. c. RENTscHLER AL 2,019,533

VAPOR'ELECTRIC DEVICE Filed Aug. 31, 1.9.53

Patented Nov. 5, 1935 PATENT OFFICE VAPOR ELECTRIC DEVICE Harvey Clayton Rentschler,

Donald E. Henry, Bloomeld, N. J., assignors East Orange, and

to Westinghouse Lamp Company, a corporation oi Pennsylvania A Application August 31, i933, Serial No. 687,602

1o ons. (ci. 17e-122) u This invention relates t'o an electric discharge device and more particularly to such a device that is adapted to be employed for illuminating purposes. More specifically the invention is an im- 5 provenient over the device disclosed in the copending application of Harvey C. Rentschler and 'Donald E. Henry, which application was led on.

August 30, 1933. bears Serial #687,391, and is f .assigned to the same assignee as the present ap- -l 0 pliction.

An object of our invention is to provide an electric discharge device of the metal vapor type whose efficiency is higher than that of similar devices'o this character heretofore produced.

Another object of our invention is to provide a metal vapor lamp whose container has a subn stance therein for rendering ineective deleterious gases which may be evolved orotherwise con= tained therein.

Another object of our invention is to provide an improved electric discharge device having indi rectly heated cathodes so arranged with an expansion element' for increasing the mechanical properties of said device during operation.

'l 25 Another object of our invention is to provide an electric discharge device having an improved novel electrode structure therein.

A further object of our invention is to provide A. an electric discharge device which may be rely assembled and transported.

Another object of our invention is to 'provide an improved electrode. structure.

Other objects and advantages of our invention vwill be perceived from the following description and drawing wherein,

Figure 1 represents a view in elevation with some parts in cross section oi a discharge device embodying our invention.

Fig. 2 represents a cross sectional view oi one 40 ofgvthe'electrodes embodying our invention.

-Fig represents a cross sectional view taken onlineIIIT-m ofFig.1. Y

Referring to the drawing, our electric discharge device which nds utility as an illuminating means comprises an elongated glass envelope le composed of boro-silicate glass resistantto sodium vapor; The ends of the envelope are in the form of outwardly extending presses li and l2 in which are Ahermetilcally sealed respective rigid leading-in conductors i3 and it hich extend exteriorly and interiorly of said envelope.

f An insulating plug I5 having a recessed portion denlng a `shoulder and a central'opening through the depththereof is located in one end of a coated nickel hollow cylinder le, serving as an electrode,

The nickel cylinder has its ends uncoated, but that portion of the cylinder between said uncoated ends has a layer of good electron emitting material, such as oxides or carbonates of calcium, strontium and barium. That portion of the con- 5 ductor i3 located adjacent the inner face of the end plug l5 is enlarged at i6' so that its cross sectional area is greater than that of the central opening of' said plug. A similar plug il ts in the other end oi said electrode it, with a rigid l0 conductor it extending through the central opening therein.

That portion oi the conductor it within the cylinder has an enlarged section l@ bearing against the plug to prevent the conductor i8 from l5` being withdrawn through said central'opening.

A short nickel rod 2t is welded to the conductor i3 to prevent longitudinal movement of the plug with respect to the conductor i3. A nickel ring 2l is welded to the conductor i8 to prevent longi-l 20 tudinal movement of the plug with respect to the conductor i8. An l. shaped conductor 22 has its short arm welded to the conductor it and its long arm to the uncoated section'oi the nickel cylinder le. A plurality of spaced light but rigid 25 nickel angles it are welded to the upper uncoated` section of the cylinder it and bear against the plug il] to further insure proper rm cooperation between the plug and cylinder. A helically coiled heater element 2d, adapted upon incandescence 30 to heat the. electron emitting material to such a temperature that requisite electron emission takes place therefrom is welded to the rods it and it. The electrode Just described is located at one end `of the envelope it. At the other end of 35 said envelope and symmetrically arranged with respect to said electrode is another electrode also comprising a nickel cylinder 25 having its ends uncoated and the portion between said uncoated portions being coated with a good electron emis- 0 sion material. A plurality oi?l plugs 2t and 2l like the plugs l5 and il, are located in the ends thereof. The conductor it and a short conductor 2t respectively extend through the central opening in the plugs 2t and 2i. Each of these conductors 45 have enlarged sections within the cylinder 25 which sections bear againet the respective plugs.

A ring or cross bar 29 is welded to the conductors ld and 28 outside of the plugs for maintaining the plugs in position. e A plurality of 50 nickel angles iid bearagainst the plug 2t and are welded to the electrode 25.`

An L shaped rod 3l is welded to the conductor llt and to the uncoated sections of the electrode 25. A coiled lamentary heater, not shown, and 55 similar to the heater 24 is welded to the rods I4 and 28 and is located in the cylinder-25.

An element 32l for mechanical expansion and contraction purposes and for other mechanical purposes is welded to the rods I8 and 28. The element 32vmay be composed of nickel or copper and is in the form of a helically wound contraction spring for maintaining the parts in straight line position as shown.

Contained Within said envelope which is first completely evacuated is a quantity of rare gas,

. such as neon, argon, helium. When argon is employed, it is preferably at a pressure of about 0.2 mm. of mercury. Together with the rare gas is a sumcient quantity of metal such as sodium, caesium, rubidium, zinc, cadmium or the like.

In the course of our experimentations with devices of this character we have found that the efciency of devices employing oxide coated electrodes to be relatively low and generally not higher than about '22 lumens per watt. The voltage drop in 'these lamps we have found to be higher than was expected. We have further ascertained that the voltage drop depends upon the particular rare gas or combination of rare gases employed with the sodium as the atmos phere within the envelope.

The voltage drop is lowest when argon is employed, higher with neon-argon and still higher with neon. Our experiments disclose that the voltage drop was lowest and about l2 volts when argon is employed and about l5 to 17 volts when neon-argon is employed, depending, of course, somewhat upon the spacing between the electrodes and the gas pressure.-

We believe that theilow lamp emciency is due in part at least to a deleterious gas, such as a diatomic or triatomic gas contained therein during the operation of said devices. Gases of this character, as for example carbon monoxide,

oxygenx and carbon dioxide are liberated fromthe electron emitting material during bombardment thereof. When the oxides, such as barium, strontium and calcium are employed as the electron emitting means, they are generally prepared by coating with carbonates of these elements the nickel cylinderv that is to serve as an electrode.

The coated cylinder is then subjected to ele- Vated temperatures whereby the carbonates are dissociated into oxides .and carbon dioxide or carbon monoxide, the latter pass oi as a gas. Even with the normal precautions taken, we do A not believe that absolutely all of the carbonates have been converted into the oxides, but that there is some carbonate left in the coating after the heat treatment. This heat treatment is carried out with the parts all assembled and with the envelope connected to the exhaust pumps and maintained in a highly evacuated condition.

After the coating has been converted to an oxide, the envelope is sealed. Some of the plum-atomic gases we believe are not entirely exhausted from said envelope, but are probably tenaciously retained by the inner wall of the envelope and the metallic parts contained therein.

During the operation of the device these gases may leave the envelope wall and the metal parts contained therein. iin addition due to bombardment of the thermionically active oxide there Vare gases liberated therefrom. It is our opinion that probably part of the emission from a barium oxide containing coating is derived from barium suboxide and barium metal which might have been formed during the breaking down of the carbonates. The residual carbonates contained in said oxide coating and probably some -of the oxide are continually breaking down during the operation of the device to liberate carbon monoxide, carbon dioxide and oxygen.k These gases are deleterious and,V therefore, adversely affect the emission and the nature of the discharge. These gases poison the electron emitting coating to lower the quantity of emission that may be obtained therefrom. This poisoning action will probably be less when the device is operated on direct current than when operated on alternating current since the peak voltages when on alternating current are higher than the direct current operating voltage and inasmuch as some of vthis gas again disappears by being driven into'one or the other electrode. The degree of gas disappearance in the electrodes is not the same Aand hence on A. C. operation this gas may partly be shuttled back and forth between the electrodes thus leaving more free gas at any one time than if operated on D. C. In addition the presence of these diatomic gases within the envelope introm duces inelastic impacts between the electrons and the atmosphere within the envelope. f

In order to obviate the above difficulties we have provided a means for increasing the efficiency of said device and this means we believe renders ineffective the deleterious gases that are present within said envelope. This means comprises an inverted metal cup 33 having a quantity of a clean up agent or getter, such as misch y metal, magnesium or the like contained therein.

The -cup 33 together with its contents is welded or otherwise secured to the conductor at a place below the cylinder it and has its open end facing away from said cylinder it,

The getter material may be vaporiaed means of a high frequency coil energization. The getter is deposited on to the end of the envelope adjacent the press i i. The getterreacts chemically with the deleterious gases to render the same ineiective during the operation of said device. After the getter is ashed in the lamp as heretofore described, we have observed that its eiiiciency may be as high as 29 to 33 lumens per watt. That is to say that the efficiency of 4a sodium vapor lamp is increased at least 30% when misch metal or similar getter is employed.

A misch metal gutter in a sodium vapor lamp lowered the voltage drop so that it was as low as 8 or 9 volts when argon was employed therewith,h

ll-13 volts when neomargon was employed therewith, and .l5-i7 volts when neon was emf ployed therewith. The values are, of course, not' fixed because they depend somewhat on electrode spacing. Lower values may be obtained or the voltages may be somewhat raised by greater spacing. In substantially all cases the voltage drop is substantially uniform for diierent lamps em.A

ploying the same atmosphere and electrode spacing.

The reason for the above-surprising results which we have obtained is due to the fact that the diatomic gases that are contained within the device as originally prepared and/or evolved durn ing operation thereof are now rendered ineiective. No longer can they poison the electrodes or reduce the elasticity of impact between the electrons and the atmosphere contained in said envelope.

An evacuated double-walled open-ended chamber 34 surrounds said device so that the proper temperature may be maintained during operation thereof. The chamber 34 and the lamp may be supported by means of a stem 35 having a are 36 oi' appreciable width and a press 31.

Wrapped around said stem and having a portion.

thereof resting upon the flare is an insulator band or ribbon 38 of asbestos whose outermost lap frictionally bears against the chamber 34. Sealed in the press 31 are a plurality of

rigid conductors

39, 40 and 4|, which extend towards the envelope I0 and only the

conductors

39 and 40 extend exteriorly of said stem. The conductor 40 is welded to the conductor I3 and the conductors 39 and 4I respectively are welded to

rigid conductors

42 and 43 which extend along, but are out of contact with the envelope I0 and are welded to the exterior portion of the conductor I4. These rigid conductors serve as electrical conducting means and supporting means for the lamp. i

Although our invention has been described with some particularity, it is to be limited only by the prior art.

What is claimed: l

1. An electric lamp comprising an envelope, an atmosphere of a condensable valkali metal vapor and a thermionically active means therein, means also within said envelope for rendering ineffective gas derived within .the space enclosed by said envelope which gas would normally lower the eciency of said device when expressed in lumens per watt, said means'having a low volatility characteristic preventing its forming a deposit throughout the envelope which would obstruct the passage therethrough of the generated light, said means having a higher activity towards the deleterious gas than does said alkali metal vapor, said means having a low combining power with said alkali metal.

2. An electric lamp comprising an envelope, an atmosphere of a condensable alkali metal gas and an electrode therein, said electrode comprising a metal base and a thermionically active oxide coating on said base and a getter therein for rendering ineffective by chemical action deleterious gas entering said atmosphere and which gas when normally present therein lowers the luminous efliciency of said device when expressed in lumens Der watt, said means having a low volatility characteristic preventing its forming a deposit throughout the envelope which would obstruct the passage therethrough of the generated light, said means having a higher activity towards the deleterious gas than doesfsaid alkali metal vapor, said means having a low combining power with said alkali metal.

3. An electric discharge device comprising an envelope, an atmosphere of a condensable alkaliy r a low combining power with said alkali metal.

4. An electric discharge device comprising an envelope, an atmosphere of a condensable alkali metal gas and an electrode therein, said electrode including Aa metallic foundation anda thermionically active oxide on said foundation and means within said envelope for rendering ineffective plum-atomic gas liberated from said coating during operation of said device and which gas when normally present would lower the lu- 5 metal and a thermionically active electrode there- 15.-

in, and misch metal within said device for increasing the luminous eiliciency of said device.-

when expressed in lumens per watt. 6. A lamp comprising an envelope, an alkali metal, a rare inert gas and a thermionically ac- 20,

tive electrode therein, said electrode comprising a metallic base and an oxide coating, and means located within said envelope at one end thereof for rendering ineffective a gas contained within said envelope which gas normally would lower the luminous eiiiciency of said device when expressed in lumens per watt.

'1. An electric lamp comprising an envelope, an alkali metal, a rare gas and a plurality of electrodes therein, one of said electrodes having a metal base and an oxide coating thereon, and misch metal at one end of said envelope for rendering ineffective gas evolved from said oxide coating which would normally lower the luminous eiliclency of the device when expressed in lumens per watt.

`8. An electric discharge device comprising an envelope, having a, plurality of presses, a plurality of electrodes in line and located in said envelope, conductors sealed in said presses and extending into said envelope, heater elements in series and electrically connected respectively to said conductors, said electrodes surrounding said elements and including thermionically active surfaces, said electrodes being electrically connected 45 to said conductors, a thermal barrier at each end of said electrodes and a mechanical expansion and contraction element connecting said heater elements.

9. An electric discharge device comprising an envelope having a plurality of presses, a conductor sealed in each press, insulators having an v opening therein through which said conductorsl pass, heater elements connected to said conductors, a coiled element connected to said heater elements, a metallic cylinder coated with a good thermionically active material surrounding said heater Lelements and having their upper and lower ends respectively closed by said insulators, other insulators'closing the other ends of said cylinder. 60 10. An electrode structure comprising a hollow body coated with a good electron emitting material, an insulating plug, having a shoulder, located at each end of said hollow body, a heater element within said body, conductors passing through openings in said insulators and connected to said heater elements, means abutting an outer face of one of said plugs and secured to said hollow body for preventing said plug from moving away from said hollow body. Y0 HARVEYCLAYTON RENTSCHLER..

DONALD E. HENRY.