US2066037A - Electron tube - Google Patents

Description

1936- c. w. HANSELL 2,066,037

ELECTRON TUBE Filed Sept. 15, 1954 lNVENTOR RH CLARE/V65 y/vsaz 7% W ATTORN EY Patented Dec. 29, 1936 UNITED STATES PATENT OFFICE ELECTRON TUBE Clarence W. Hanscll, Rocky Point, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application September 13, 1934, Serial No. 743,813 Claims. (Cl. 250-275) 5 source toward an anode electrode and shifted inits passage between the source and the electrode by means of some suitable deflecting field.

One of the primary objects of the present invention is that of eliminating the effects of secondary emission from the anodes upon which the electron stream impinges.

A further object of the invention is that of lowering the internal resistance of the tube to the flow of electron currents.

Still a further object of the invention relates to general improvements in the design of electron tube structure.

By the prior art, as is evidenced, for example, by my-previously issued Patent No. 1,850,104, granted on March 22, 1932, assigned to Radio Corporation of America, I have shown an electron tube particularly adapted for a system wherein the effects of tube noises are eliminated and have applied a tube of the cathode ray type to use in an amplifying system. By this arrangement of the prior art the efiects of secondary emission from the anodes were reduced to some extent by providing a shield between the two anodes and the source of electrons. However, by the present invention I have been able to overcome to a still greater extent the detrimental effects of secondary emission in tube operation in a manner which was not heretofore attainable.

Briefly, the new feature embodied in the present invention consists in the use of cup-like anodes so designed and spaced relative to the elements of the accelerating grid'that all of the electrons issuing from the emitting elementstriking the anodes do so inside the cup-shaped portion where there is very little, if any, potential gradient and where, as a result, secondary emission which results from electron impact will not be drawn out.

The invention is illustrated'in one of its suggested forms by the accompanying drawing, wherein:

Fig. 1- represents conventionally a sectional view through an electron tube of the type herein disclosed and shows the tube applied to an operating circuit of the general type shown in my previously acknowledged patent; and

Fig. 2 illustrates a tube of the type shown in Fig. 1 also in section along the line 2-2 of Fig. 1 looking in the direction of the arrows.

66 If reference is now made to the accompanying drawing, it will be seen that I have provided a tube l formed of a glass envelope and appropriately evacuated. Within the tube l and supported from the stem portion 3, I have provided a large area cathode 5 which preferably consists of a thin piece of metal heated by low voltage low frequency electric current supplied thereto by means of conductors I and 9 at one end and l and 9' at opposite end, so that two parallel supply paths are formed. The cathode of the preferred type as I have shown it preferably has a cross-section in a plane at right angles to its length which approximate very closely a parabola, since I have found that a large area cathode ofparabolic shape will result in large electron emission combined with a concentration of the electron stream so that under proper conditions a closely concentrated beam of electrons of considerable strength will be focused upon the center of the accelerating grid structure I I.

The focusing of the electron stream issuing from the cathode may further be improved by means of suitable control electrodes l3, for example, which are arranged substantially adjacent the emitting cathode and are given such shaping as to make them substantially continuations of theparabolic shaping of the cathode. Of course, it is desirable in most cases to provide some spacing between the controlling electrodes I3 and the cathode structure 5 for insulating purposes. The electronbeam thus issuing from the cathode surface 5 and passing through the grid H and controlled by the controlling electrodes I3 is arranged to impinge upon the internal portion of the cup-like anode members l5, I6 which are supported within the end of the tube opposite the electron source.

As I have already pointed out in what has gone before, electrons issuing from the emitting surface 5 are drawn over to the anode members l5 and It by virtue of the voltage applied between the anode and the emitter and upon striking the anode tend to cause the anode surface to emit secondary electrons. By arranging the anode electrodes in cup-shaped fashion, as above explained, the effects of secondary emission do not extend beyond the boundary confines of the anode structure and, therefore, will not result in a current flowing from the anodes.

In order to provide further'improvements in the'operation of a tube of the general type herein disclosed, I have arranged at each end of the emitting electrode 5 a shield member I1, I!) for thelpurpos'e of concentrating the electron stream in a direction parallel to the length of the cathinputcircuitAtoa-n outputcirwit n. Aswas my above mentioned Patent No.

mm. Aoittlrding to the drawing, the shields ireshownasconnectedtotheendsoithecathodeand forming, at the same time, apart of the cathode support.

Intheconstructionotatubeoithegeneral aratherlarge electron'emiasion.

'roprevent emission from one anode llor ll rachingtheotheranodeandtoguardagalnst any possibility of inemciencies in operation, shielding structure 2| is supported within the tube to separate the two anodes, and in order to catch most oi the electrons when no energy is applied on the control elements and also to catch all electrons which are 'insufllciently de-" flected by the deflecting or controlling electrodes II to fall within the anode cups, the metal-like brldgestructureflisprovidedinthegrld. Also, the grid structurein itsposition between the.

anodes II, II and the controlling electrode l3 electrodes".

Inordertoshowthegeneraltype'ofsystem adeviceqtthlstypeoperates,l'lg.l drawing illustrates one suitable dorm enemistobe transmitted from one 1,850,104, energy supplied from the input circuit is passed through the transformer coupling I tuned y applied to the controlling electrodes l8 connected to suitable terminals on the base member the tube IL The central portion ofthe radio transmitter, for example, andthe output issuitahlytunedbymeansoiacondens'er ll.

voltage for drawing the electrons from the emitting surface 3 toward the anodesili, ll

isprovidedbytheinolusionotsourcesot'potentialflandll. Betweentheemittera'ndthe anodmandgr'idsavoltegeotthesoumell alone isappliedtothegridstructurell. Heatingcurrenttorheatingtheemitter iissuppiied by wayotasourcellandmaybeeitherdireetor alternating current;

Homiislgnalsareappliedin thelnputcircuit' A,they arecaused to aiiect or control'thecontrolling ordeiiecting electroda llandthus'eause theelectronstreamdevelopedtobepessedbe-- tween the two independent cup-like anode membei'siiand llwiththeresultthatcm'rentiiows meanso'ithecondenserflsoasto- "aoeaos': a e

inthewtputclreuit'BJs'wesexplainedinmy previouflymentionedpetent.

Whileithasnothereinbeenshowmitiaoi Having may described the invention. what no a plurality of cup-shapedanode memm I Ir arrangedrelatlvetotheelectron unittir element, apair o! deflecting elemenh the emi tine el men the anodeaiia' calling the electron streamto be shifted law-em the plurality of anodes,, and meami'orshhldingtheanodesfromthedeflecting (An electron tube comprising an-evacuated envelope, an elmaated electron emitting element or parabolic cross-section, a plurality 01' cupahaped anode members symmetrically arranged relative to the emitting element, and a plurality or deflecting. elements positioned intermediate the emitflng element and the anodes.'sald deflectingelecllolhalyingsubstantiallyintheplaneextendedol the surface of said emitting member. 5.Anelectron tubeeomprising anevacuated envelope, an elongated electron emitting element or parabolic cross-section, a plurality of cupsbapedanodenmnberssymmetricallyarranged relativetotheelnittingelement;apairotdeiiecting mi: intermediate the emitting elementandtheanodaanda shieldelementateach endotihecnittingelement for preventing ing at the unltted electrons in it direction longi-..

tudimliy ot the unitting element.

a. An electron tube a an evacuated container homing therein an electrode element M to emit electrons, t pluol'anode adapted'to receive the rality electrons buing from the first electrode, anodeehnmtabdngcup-shapedtoreducesubatantiallytoaero the effects oi'secondary electrunk-ma plurality of control electrodes positimed intermediatethe'electronsourceand theanodemanberaandagridstruotureintermediate the control electrodes and the anodes to provide feed back of energy from the anodes to the control electrodes.

'7. An electron tube comprising an evacuated envelope, an elongated electron emitting element of parabolic cross-section for emitting a stream of electrons of substantial dimensions relative to the tube envelope size, a plurality of cupshaped anode members symmetrically arranged relative to the electron emitting element, a pair of deflectingelements intermediate the emitting element and the anode electrodes for causing the electron stream to be shifted between said plurality of anode electrodes, a shield element at each end of the emitting element for preventing spreading of the emitted electrons in a direction longitudinally of the emitting element, and means within the envelope for shielding the anode electrodes from the deflecting elements and electron source.

8. An electron tube comprising an evacuated container housing therein an electrode element adapted to emit electrons, and an anode electrode adapted to receive the electrons issuing from the emitting electrode, said anode element being constructed cup-shape so that electrons received thereby are unable to cause secondary electronic emission from the anode to have any substantial effect beyond the boundary limits of the anode structure.

9. An electron tube comprising an evacuated envelope, an electron emitting element within the envelope, a plurality of cup-shaped anode members symmetrically arranged relative to the emitting element, means for electrostatically shielding the anode members from each other, and a pair of deflecting elements intermediate the emitting element and the anodes.

10. An electron tube comprising an evacuated envelope, an elongated electron emitting element of parabolic cross-section, a plurality of cupshaped anode members symmetrically arranged relative to the emitting element, means for electrostatically shielding the anode members from each other, and a pair of deflecting elements intermediate the emitting element and theanodes.

11, An electron tube comprising an evacuated envelope, an electron emitting element within the envelope, a plurality of cup-shaped anode members symmetrically arranged relative to the electron emitting element, means for electrostatically shielding the anode members from each other, a

pair of deflecting elements intermediate the emit-- ting element and the anodes for causing the electron stream to be shifted between the plurality of anodes, and means for shielding the anodes from the deflecting elements.

12. An electron tube comprising an evacuated envelope, an elongated electron emitting element of parabolic cross-section, a plurality of cup-shaped anode members symmetrically arrangedrelative to the emitting element, means for electrostatically shielding the anode members from each other, and a plurality of deflecting elements positioned intermediate the emitting element and the anodes, said deflecting electrodes lying substantially in the plane extended of the surface of said emitting member.

13. Anelectron tube comprising an evacuated envelope, an elongated electron emitting element of parabolic cross-section, a plurality of cup-shaped anode members symmetrically arranged relative to the emitting element, means for electrostatically shielding the anode members from each other, a pair of deflecting elements intermediate the emitting element and the anode, and a shield element at each end of the emitting element for preventing spreading or the emitted electrons in a direction longitudinally of the emitting element.

14. An electron tube comprising an evacuated container housing therein an electrode element adapted when heated to emit electrons, a plurality of anode members adapted to receive the electrons issuing from the first electrode, said anode elements being cup-shaped to reduce substantially to zero the effects of secondary electronic emission, means for electrostatically shielding the anode members from each other, a plurality of control electrodes positioned intermediate the electron source and the anode members, and a grid structure intermediate the control electrodes and the anodes to provide feedback of energy from the anodes to the control electrodes.

15. An electron tube comprising an evacuated envelope, an elongated electron emitting element of parabolic cross-section for emitting a stream of electrons of substantial dimensions relative to the tube envelope size,-a plurality of cupshaped anode members symmetrically arranged relative to the electron emitting element, means for electrostatically shielding the anode members from each other, a pair of deflecting elements intermediate the emitting element and the anode electrodes for causing the electron stream to be shifted between said plurality of anode electrodes, a shield element at each end of the emitting element for preventing spreading of the emitted electrons in a direction longitudinally of the emitting element, and means within the envelope for shielding the anode electrodes from the deflecting elements and electron source.

CLARENCE W. HANSELL.

Images