US1903145A - Bectifying- tube - Google Patents

Description

March 28, 1933. H. J. SPANNER ET AL RECTIFYING TUBE Filed March 11, 1929 1?NVENTOR Ha/zsJJ aa/zner ATTORNEYS Patented Mar. 28, 1933 UNITED STATES PATENT OFFICE ms J. SPANKED, 0] BERLIN, GERMANY, AND ULRICH DOEIRING, OF NEW YORK, N. Y ASSIGNOBS TO'ELECTBONS, me, A CORPORATION OF DELAWARE RECTH'YING TUBE Application fled larch 11, 1989, Serial 110. 848,120, and in Germany June 19, 1928.

This invention relates to rectifying devices and more particularly to such devices which have a heatable cathode and which are gas filled and operate by means of an elec tric discharge through an ionized gas as distinguished from rectifying devices which operate by means of a pure electronic discharge.

Among the objects of the invention is the production of a rectifying tube capable of operating at higher voltages and with a greater current capacity than has been heretofore the practice,

Further objects are the attainment of a higher efliciency and longer life and also freedom from external disturbances.

In order to confine the discharge path within as small a region as possible a cham her or inclosing shell is provided which surrounds the electrodes. Because of the limit- 'ed space within which the discharge then takes place it is desirable to provide screens or partitions between the anodes to prevent discharge therebetween.

It is also one of the objects of the invention to provide a simple and rugged construction for the purpose described and one which is adapted to withstand the jars and vibrations of ordinary usage.

These and other objects of the invention will appear to those skilled in the art to which it appertains by a consideration of the following description of different embodiments thereof takenrin connection with the accompanying drawin'g, in which Fi 1 is a vertical section of a two-anode recti ying device in which the anodes are directly connected with an inclosing shell;

Fig. 2 is a perspective view, partly in section, of a three-anode rectifying device in which the anodes are connected with an inclosing shell through resistances; and

Fig. 3 is a vertical section of a modified form of rectifier in which the two parts of the inclosing shell constitute anodes.

The reference character 11 indicates a bulb or tube of glass having a glass stem 12 in the lower portion thereof through which are carried leading-in wires 13 and 14 for a cathode 15. Surrounding the cathode 15 is an 'inclosing shell divided into two parts 16 and 17 from which extend inwardly projections or knobs l8 and 19, respectively, on

parts thereof are supported by suitable brackets 20 and 21, the lower ends of which are carried by the glass stem 12. Thelower ends of the brackets are also connected with leading-in wires 22 and 23.

The two parts 16 and 17 of the inclosing shell are separated by an insulating partition or disc'24 of a material such as burned zirconium oxide which partition has an opening 25 therein in which is positioned the oathode 15. The partition should extend well beyond the shell on the outside thereof depending on the voltage of the tube and may be provided with an annular ridge 26 on each side thereof by means of which the disc 24 is supported by the shell 16-17. It is not necessary that this ridge should extend all around the shell, but it may be omitted on the under side where the leading-in wires and partition are close together. Suitable insulating tubes 27 and 28 of zirconium oxide or beryllium oxide may be provided for the cathode leading-in wires where they pass through the shell. The gas filling of the tube may be one of the rare gases such as neon, argon or helium or a mixture thereof. The above gas filling may also have a metal vapor such as mercury vapor added thereto. Or the filling may consist of some other gas such as nitrogen or hydrogen which has no appreciable action on the heated cathode.

The heated cathode may be a helical wire and is preferably of the Wehnelt type which has a coating of a highly emissive substance. This may be one of the compounds such as an oxide, carbide or silicide of a metal such as barium, strontium, caesium or rubidium or the metal may housed in the-metallic form. These materials are used preferably with an oxide of an amphoteric compound such as aluminum, chromium, zirconium or nickel oxide.

It will benoted that the anodes are disposed on opposite sides of the cathode and the arrangement is such that any discharge path between the anodes lies through the region adjacent to the cathode and because of the negative field near the cathode any actual discharge between the anodes is effectively prevented as the shell and partition' provide a barrier to the ions for any other path than through the cathode region. The opening 25 may befsomewhat larger than the cathode as the electrons are available in greater numbers than the positive ions for some distance away from the cathode. Also it is to be noted that the anodes may be placed close to the cathode without danger of breakdown therebetween which results in a shorter discharge path and lower voltage drop through such path. This results in a higher efliciency and in a tube that will not readily overheat. The loss of heat is also prevented both through radiation and by convection currents because of the inclosing shell. The shell also prevents the formation of wall charges on the inside of the tube and renders the discharge more stable.

In Fig. 2 the inclosing shell is divided into three parts 29, 30 and 31 within which are disposed three anodes 32, 33 and 34. The adjacent anodes are separated from each other by an interposed partition 24a consisting of three equally spaced wings 35, 36 and 37. The three-wing partition 24a is supported by a bracket 38, the lower end of which is embedded in the glass stem 12. The anodes 32, 33 and 34 are connected with the leadingin wires 39, 40 and 41 respectively and each wire is surrounded by an insulating tube 42 throughout its length from the glass stem, through the inclosing shell for the anode, and close to the anode itself. The material from which the insulating tubes are formed should, have little or no tendency to crack or dis integrate under sudden and great temperature changes and furthermore there should not be developed gases where the tube comes in contact with the anode which is nearly at incandescent temperature. In the modification shown in Fig. 2 the anodes are connected to the respective parts of the inclosing shell through resistances 43 which may be in the form of small cylinders of silicon or carbide of silicon and each cylinder may be held in place by a strip 44 of the sheet nickel of which the inclosing shell is formed. By giving to the resistance a suitable value the potential of the shell may be brought as closely. as desired to that of the anode knob.

In Fig. 3 the inclosing shell is composed of graphite and the two parts thereof 16a and 17a constitute the anodes. In this arrangement the shell is made somewhat smaller to bring the anodes close to the hot and emitting cathode and to confine the discharge path to a small volume. A partition 24a separates the two anodes and may be constructed of a core 45 of sheet metal and an outer insulating portion 46. The chief advantage of the embed- (led conducting part is the opportunity which it affords for convenient de-gasing by heating the part with eddy currents from a highfrequency coil. The metallic plate also renders the dividing partition somewhat stronger mechanically. In operation each anode carries a current for one half of a cycle and then is inactive for one half of a cycle. During the active period the current flows from the anode to the cathode with a relatively low voltage drop, the balance of the voltage being consumed in the load circuit. During the inactive portion of the cycle, however, full supply voltage is impressed between the anodes with a maximum tendency to cause breakdowns or short circuits between anodes. The complete inclosing of the gaseous discharge prevents the space lying outside of the shell from becoming ionized and therefore the only discharge path between anodes at moderate voltages lies through the negatively charged region adjacent to the cathode through which no short circuit discharge is possible. Because of this freedom from danger of short circuits it is possible to operate the tube at higher potentials than heretofore. Also the compact space within which the discharge is confined shortens the discharge path, reduces the voltage drop through the discharge path with consequent lower losses, higher etliciency and reduced operating temperatures. Because of the lower voltage drop through the discharge path the velocity of the ions is less and the disintegration of the cathode because of ion bombardment is much less. Furthermore the inclosing shell prevents the formation of wall charges. This renders the operation of the tube more stable and less subject to external influences. It also reduces the losses resulting from the ions and electrons neutralizing one another on the walls of the tube.

Furthermore it will be seen that a rugged and simple structure has been provided for the foregoing purposes and one that is not likely to be broken by the ars and vibrations of ordinary use.

We claim:

1: A gas filled rectifying device comprising a tube. a heatable cathode positioned therein, a conducting shell surrounding and substantially inclosing the cathode and divided into a plurality of parts, each part forming an independent anode for cooperation with said cathode, and a partition separating adjacent anodes, said partition being formed of insu-' lating material that retains its insulating properties and does not emit gases throughout the temperature range to which it is subjected, and a metallic plate embedded in the inner portion of said artition. I

2. A gas filled rectlfying device comprising a tube, a heatable cathode ositioned therein, and a pair of substantia y hemispherical conductin shells surrounding the cathode, each of said shells forming an anode for cooperation with the cathode and having an inwardly extendin knob for carrying the greater ortion of t e current discharge of the ano e.

3. A gas filled rectifying device comprising a tube, a heatable cathode ositioned therein, and a pair of substantially hemispherical conducting shells surrounding the cathode, each of said shells forming an anode for coopera tion with the cathode and having an inwardly extending knob for carrying the greater portion of the current discharge of the anode, the surfaces of the knobs being carbon.

4. In a rectifier device, a plurality of anodes, a barrier for isolating said anodes, said anodes and barrier forming a complete enclosure, said barrier having an opening, and a cathode common to said anodes in said opening.

5. In a re ctifying, device, a plurality of anodes, a barrier for isolating said anodes, said anodes and barrier forming a complete enclosure, said barrier having an opening, and a cathode common to said anodes in said opening, said barrier extendin beyond said enclosure for more completely isolating said anodes from each other.

6. In a rectifying device, a plurality of anodes, a barrier for isolating said anodes, said anodes and barrier forming a complete enclosure, said barrier having an opening, and a cathode common to said anodes in said opening, said barrier extending beyond said enclosure for more completely isolating said anodes from'each other, said barrier comprising insulating material which retains its insulating properties and does .not emit gases at any temperature in the range to which it is subjected.

7. A rectifying device comprising a plurality of independent-anodes, a barrier for isolating said anodes, said anodes and barrier forming a complete enclosure, said barrier having an opening, a cathode common to said anodes in said opening, said barrier extending beyond said enclosure for completely isolating said anodes from 'each other, said barrier comprising insulating material which re tains its insulating properties and does not emit gases throughout the temperature range to which it is subjected, and a metallic plate embedded in the inner portion of said barrier.

8. A gas filled rectifying device comprising a tube, a heatable cathode positioned therein, and a conducting shell surroundin and substantially inclosin the cathode and divided into a plurality 0% parts positioned on op site sides of said cathode and electrically insulated from each other, each part forming an independent anode for coo ration with said cathode, the cathode having a coating comprisin a highly emissive substance and an oxi e of an amphoteric compound.

9. A rectifying device comprising a plurality of anodes, a metallic barrier therebetween, a cathode, insulating material between said barier and said anodes electrically insulating the anodes from the barrier and from each other, and means for bracing said anodes against said barrier.

10. A rectifying device comprising the combination defined in claim 9, in which said barrier is sup orted by said anodes.

11. A rectiig ing device comprising a pair of cup-shaped anodes made of a metal in the iron group, said anodes being disposed with their openlngs adjacent to form a. hollow shell, a heatable cathode disposed at the approximate center of said shell, a barrier of zirconium oxide separating and electrically insulating said anodes, said barrier extending outwardly beyond the peripheries of the anodes and inwardly to a region within the negative field of the cathode, and a carbon knob electrically connected to each anode, said knobs being disposed between said cathode and their respective anodes.

HANS J. SPANNER. ULRICH DOERING.

CERTlFIGATE 0F CORRECTION.

Patent No.l,903,145. March 28, 1933.

HANS J. SPANNER, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, lines 25, 31, and 39, claims 4, 5, and 6 respectively, for "In a" read "A gaseous", and after "device" insert the word "comprising"; same page and claims, lines 26, 32 and 40 respectively, before "anodes" first occurrence insert the word "independent" and for "for" read "electrically"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of May, A. D. 1933.

M. J. Moore. Acting Commissioner of Patents. (Seal)

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