US2007941A - Electric discharge mantle - Google Patents

Description

y 1935- c. H. BRASELTON ELECTRIC DISCHARGE MANTLE Filed Aug. 27, 1950 INVENTOR Patented July 9, 1935 ENT 2.0mm ELECTRIC mSe ee E,

; Chester. H. Braselton, New York, N! .1 assignor ,Sirian Lamp Germa Ntwer J a 29 n tei oa at De a ar App t n August 27, 1939, Serial No. 478,059

7 5 Cla ms- (01. re- 1 This invention relates to devices adapted for e ss on o r iant n g art p e l 1 91 d ice swamps. hi h er -u for lumi ation. v 1

bi c i h nv n i n s t v p ovid a type of lamp which employs as a radiating element a selective light emitter of the Welsbach mantle.

Another object of the invention is to provide new means for activating the light emitting sub stances of a selective "light emitter, such as the combination oi the oxides of thorium and cerium. Another object is to' utilize the energy given oil? in the form of highly activated gases adjacent the conductor which is coated with an electron emitting material and heated in an atmosphere of inert gases at a pressure reduced from atmospheric. 1

Another object is to provide a mantle type of electric emitter which has substantial strength of construction sothat the lamp may be readily handled. without'danger of fracture of the mantle element.

Other objects contemplated will appear on consideration of the following description and of the accompanying drawing, --which Fig.1 is a View inelevation of an embodiment of the invention showing apart of theniantle broken away to =i l lustrate the ionizing element; f-Fig. 2 is a'yiew-of a 'modification of the invention in whichthe gas type mantle is employed; Fig. 3=-is-asection oi -the' mantle material of Fig.1;

Fig.4 is a section of the mantle material of Fig. 2; 1 i 3 :5 is a view showing thegas ionizing element; i Fig.6 is a sectional view-taken alonglines -6'--6 of Fig. 1; and T r i a Fig. '7 isxa sec-tion of the lightemitting unit of the lamp illustrated :in Fig. and taken along the lines fi-lwofthisufigure. .:-In my coapending application Serial -No. 459,-

043, filed June 3, 1930, I have-described a forrn or energy radiating. device in which -I emplo layer .ofsioni'zedlgases aimmediately adjacent a conductheymt mu a r. :t rm .eners 'lenitt h tyre ti i zel'ie the.

high intensity. In accordance with said application, a filament of appropriate resistance, such, for example, as 150 ohms, is placed in heating relationship with various alkaline earth metal Q oxides, such as the oxides of barium,"strontium, 5 calcium, or other materials which have been found to "emit electrons densely when heated. The base filamentis tungsten 'oi'" tantalum wire, although other metal conductors may be used. It is not necessary, ordinarily, that the base material be highly refractory, as the operating 'tem: peratures may be relatively low, inmany cases not being above that of low red heat.

The filament is preferably coiled and the oxides either applied as a paste to the exterior of the coil, or as a core or rod to the coil interior.' "The oxide material initially may be inthe proportions of 40 grams of bariumcarbonate', 40 grams of calcium carbonate, 8 grams of barium nitrate with a binder of sufi icient nitrocellulose dissolved in amyl acetate to hold the coating on the wire. The filament then mounted on'a stem support and' sealed in the bulb of 'the envelope. 1 v

The exhaust pump is then connected to the bulb and an ovenlowered thereupon to raise the temperature of 'the bulb and contents to about 409 Q, or to as high a temperature as the envelope will stand without softeningf Simultaneousl'y, electri cfeurrent is passed throug h' the filament, which is heated to redheatof a'ppro'i'ii mately600 C. The heat and'eiihausting process is continued until there is no "fluorescence" when the high tension current is directedagainst'the wall of the bulb, or mother words, until there is practically no rnore gas inside of the bulb. A vacuum "of about one-half of a' rnicro'n 'is an approximate-limiting value.

micron is again obtained.

-The pump is then shut ofhthe current turned off, and aboutone-half mm; of n p'z i'gas admitted to the bulb. 'lhei'llarnent current isthe n turned 'on 'and gradually'increased until a difiu sedlglow complet y-ens; the bulb. When the teenage is'ii t tq'tiait et iea .th -btlbaih fi r 911 rattan 1400 c.

with the pumpoperating, to remove any underods-it is an indication that the gases or vapors 1 within the bulb have not been completely removed, and the bulb is again exhausted and the whole process of activation repeated.

With the activation process satisfactorily repeated, the filament circuit is disconnected and the pump turned off and the appropriate amount of gas admitted to the bulb. In one form of my invention I utilize neon and argon gases in the relative amounts of 50 mm. of neon gas, and mm. of argon. Other monatomic gases, such as krypton, helium or metal vapors, such as those of mercury, caesium and rubidium, may also be used. The bulb is then sealed off and a small quantity of magnesium flashed to absorb additional impurities, thus completing the process.

In applying the principles of the energy emitter above described to the present invention, I insert in an envelope or container I0 of transparentmaterial, such as glass, a stem or support il which is sealed to the container. The support H carries three standards l2, l3 and 14, which are pressed into the stem or support and have external sections, the standards l3 and M connecting with lead-in wires l5 and Hi upon which a potential is applied to the lamp. A cross support rod i1 is attached to the upper end of the standard l4, and between the end ill of the support rod and the standard I3 is connected a closely wound coil 19 of tungsten wire within which has been inserted electron emitting material 28 of a composition similar to that hereinabove described, such as the various oxides of barium, strontium, calcium, or other alkaline oxides which have been found, when heated, to emit electrons in profusion. The material 28 may form the core of the coil 19, or may be applied externally thereto, the essential requirement being that the coating, which term applies to the substances either internally or externally, should be in heating relationship with the coil I9.

Surrounding the coated conductor I9 with its conductor 20, and which, as an emitting unit, may be referred to by the numeral 2 l, is a cylinder 22 of refractory metal in gauze form, that is formed either by stamping or by a method of weaving. The cylinder has numerous interstices or apertures formed therein which are intended to permit the movement of gases freely from within to without the cylinder. The cylinder 22 carries a coating of selective light emitting material such as the combination of thoria and ceria used in the manufacture of the Welsbach mantle. As is well known, with certain definite percentages of these substances, approximating 99% of thoria and 1% of ceria, a substance, is produced which, when heated, emits a brilliant white light.

. This material has been used successfully in conjunction with a gas flame, the burning gas heating the filamentary strandsof mantle material to luminous temperatures.

In applying the' coating 23 to the cylinder 22 the coating material should be sufiiciently thin so as not to cake over the surface and obstruct the apertures. Alternatively, the mantle structure of the commercial type of gas mantle could be applied externally or internally to the metal cylinder, provided the cylindrical metal support is not in such close contact with the material as to maintain the temperature of the emitting material below the luminous temperature. Other means may be utilized for maintaining the broken character of the coating so that gases may freely penetrate and activate the coating.

The activating and heating unit 2|, together with the coated mantle unit 24, being mounted on the support H, are included within the container It. Inert gases of the type hereinabove described, such as argon neon, helium and nitrogen and the like, or mixtures of these gases with each other or with various metallic vapors such. as mercury, caesium, and rubidium, are placed within the container.

In operation, when a potential is applied to the lead-in wires l5 and E6, the emitting unit 2| becomes heated and activates the gases immediately surrounding the same. These gases, in the shape of a luminous discharge, penetrate the light emitting cylinder 24 with its coating 23, and causes the same to be heated by radiation, gas convection and by electron bombardment, all of said agencies bringing the temperature of themantle material up to a brilliant luminous temperature, thus making the lamp useful for illuminating purposes.

In Fig. 2 there is illustrated a modification of. the invention in which mantle material of the commercial type now used for gas burners is employed. On the support H within the container ID are mounted the standards 33, 3|, 32, and 33, and to the top of the standard 33 a cross bar 34 is attached. Intermediate the end 35 of this cross bar it and the standard 3! is interposed the coil 36 of tungsten or other refractory metal within which is a core 3'? of an alkaline earth metal oxide, such as those of barium, strontium and calcium. The mantle 38 surrounds the conductor 36 and may consist of two sheets of the material clamped together by the split tubes 39, which likewise clamps and retains the support rods 40 and 4|. These rods are in turn welded or otherwise secured to the standards 30 and 32. The mantle fabric is held so as to be curvilinear in its contour as shown in Fig. '7. In this form of the invention there is no metal backing or support for the mantle, and consequently, the lamp is; more fragile. It is within the scope of the inven-- tion, however, to apply non-metallic backing to the mantle or to include inert substances which will strengthen the light emitting material.

The operation of the modification of Fig. 2 is similar in all respects to the operation of the device shown in Fig. 1. Due, however, to the lesser heat conductivity of this second form, the heat absorbed by the illuminating unit is not so great as in the case of the first described modification. The electric current passing through the ionizing element causes the formation of a halo or layer of activated gases adjacent the conductor and its coating, which penetrating the mantle, causes it to radiate light energy.

The use of inert gases seems to be essential for the operation of the lamp inasmuch as chemical reactions within the lamp are undesirable. Moreover, the breakdown potential of the gas should be lower relatively than the potential necessary to activate the coating of the conductor by heat energy derived from the current flow.

The term coating as used in the specification and claims is intended to cover not only the material as applied externally but internally of the heating coil, and similarly, the term electron emitting temperature is intended to signify that temperature of the coating or of the conductor at which the coating emits electron in pronounced density.

Various other modifications of the invention as hereinabove described may be made, and hence I do not desire to be limited tothe modifications shown, except as required by the interpretation of the claims hereto appended.

I claim as my invention: 1 1

l. A lamp comprising the combination of a container, a support mounted therein, a plurality of standards'mounted on said support, a conductor electrically connected betweentwo of said standards, said conductor being formed of a coil of refractory wire, a coating of electron emitting material adjacent said conductor, a tubular metal screen surrounding said conductor and supported by other of said standards, a coating of oxides on said screen adapted when heated to emit light selectively, and an inert gas within said container, the pressure of said gas preferably exceeding 100 mm. of mercury and possessing a breakdown potential of such value that a layer of highly conducting gas is formed between the conductor and the metallic screen when the emitting material ,is heated by an electric current in the conductor;

2. A lamp comprising the combination of a transparent container, a support mounted therein, an ionizable gas within the container, a plurality of standards on said support, a linearly extending conductor mounted between two of said standards, said conductor being in the shape of a coil of refractory wire, a coating of alkaline earth metal oxides emitting electrons profusely when heated adjacent said conductor, a non-metallic perforated barrier surrounding said conductor and supported by other of said standards, said barrier being of material which when heated will emit light selectively and in excess of the light emitted by refractory metals at the same temperature.

3. A lamp comprising the combination of a transparent container, a support mounted therein, an ionizable gas within the container, a plurality of standardson said support, a linearly extending conductor mounted between two of said standards, said conductor being in the shape of a coil of refractory wire, a coating of electron emitting material on said conductor, said coating including the oxide of strontium, a non-metallicperforated barrier surrounding said conductor and supported by otherof said standards, said barrier being of material which when heated will emit light selectively and in excess of the light emitted by refractory metals at the same temperature.

4. A gas discharge lamp comprising a container, a perforated metal tube therein, a coating of light-selective material on said tube, and means for forming a gas discharge within said tube, said means including a filament within the tube, a coating of electron emitting material containing an oxide of the alkaline earth metals on said filament and an i-onizable gas within the container.

5. An energy radiating device comprising a container, a support mounted therein, a single conductor mounted on said support, means to connect both ends of said conductor to points outside of said container, a coating of electron emitting material having an electron emissivity equal to that of the alkaline earth metal oxides on said conductor, a tube of solid material enclosing the coated portion of said conductor and mounted on said support, and an ionizable gas within the container, said gas having a breakdown potential per unit length lessthan that of the unit length of conductor necessary to raise the coating thereon to electron emitting temperature.

CHESTER H. BRASELTON.

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