US2265311A - Electron beam tube - Google Patents

Description

Dec. 9, 1941. F. PREISACH E TAL ELECTRON BEAM TUBE 2 Sheets-Sheet 1 Filed March 23, 19.59

Dec. 9, 1941. F. PREESACH ETAL.

ELECTRON BEAM TUBE Filed March 23, 1939 2 Sheets-Sheet 2 I Fig- Patented Dec. 9, 1941 ELECTRON BEAM TUBE Ferenc Preisach and Imre Zakarias, Budapest, Hungary, assignors to United Incandescent Lamp and Electrical Company, Ltd., Ujpest,

Hungary Application March 23, 1939, Serial No. 263,708 In Germany March 29, 1938 3 Claims. 01. 250-151) Our invention relates to electron ray valves,

more especially of the kind in which means are provided for deflecting the electrons of the ray. It is an object of our invention to improve this type of valves in several respects, as will appear more in detail as the specification proceeds.

As is well known, electrical alternating voltages can be amplified by directing the electrons of an electron ray in timely alternation from one collector electrode onto another by influencing;-

ing facts can be ascertained. If one succeeds in? so far increasing the sensibility of the electron control (mutual conductance of the valve) by a suitable dimensioning of the deflecting control members, as is the case in space-charge controlled valves, it will be found that the inner;-

resistance in the electron ray valve is considerably lower, so that an amplification such as is possible with a space-charge controlled screen grid valve, is not obtainable. On the other hand the electron ray valves with deflection control; offer the basic advantage, as compared with the space-charge controlled valves, that the electrons are not braked, the electron paths being only deflected through small angles, whereby the formation of space-charge clouds in the, high frequency field is avoided, which are known to involve certain disadvantages at higher frequencies. These disadvantageous effects are particularly known in the modern mixing valves (hexodes, octodes); the distribution control, by,v means of the outer control grid, which is employed in these valves, is not a deflection control, because here the paths of the electrons are bent completely, whereby disadvantageous phenomena arise.

The improved electron ray valve according to the present invention combines the advantages offered by the deflection control with the high amplification value of the space-charge controlled screen grid valves.

In the drawings affixed to this specification and forming part thereof a valve embodying our invention is illustrated diagrammatically by way of example.

In the drawings:

Fig. 1 is a diagram of connections of this valve, while Figs. 2-5 show details of diiferent arrangements of the screens and anodes.

Figs. 6 and '7 are diagrams showing further modifications of the valve according to this invention.

In all the figures K is the cathode, G the control grid, A1 and Azacceleration and ray concentration electrodes, respectively, P1 and P2 deflecting electrodes, SG, SG1 and SGz are screen grids, BG is the suppressor grid, A and A are working anodes, HA is the auxiliary anode, S and S are electrodes for concentrating the ray to about cathode potential. L1 is the inductivity and C1 the capacity of the input oscillation Y circuit, L2 and C2 the inductivity and capacity,

respectively, at the output of the valve; C3,' C4 and C are bridging condensers, E is an' anode voltage source, R a voltage divider resistance and St and St are electron paths. On testing the inner resistance of the working anode A of an electron ray valve such as shown in Fig. 1, the following effects can be ascertained, which render the anode current dependent from the anode voltage:

1. Passage from the anode A to the control member PzP1.

2. A secondary emission exchange between the working anode A and the auxiliary anode HA.

3. A deflection of the ray in the critical range at the passage of the bundle of rays StSt (passage of current) y from one anode to the other.

In order to avoid the first mentioned eifec t, it appears obvious to arrange a screen grid SG1 in front of the anodes A-I-IA, as is usual in space charge controlled electron valves. In analogy with the screen grid valves fitted with suppressor grids it is also advisable to avoid the exchange of secondary emissions by the insertion of a suppressor grid BG. The tests have however shown that by these obvious steps the intervalve resistance cannot be increased sufficiently. For it has been found that the differential inner resistance of the anode circuit in the critical range of passage of current drops by one-tenth, for instance from 500,000 ohm to 50,000 ohm in in the case of an anode current of 3 milliampere. Our invention is based on the perception that this electron-optical influence of the working anode on the intervalve resistance is decisive and that it can be done away with by the screening methods according to this invention.

Arrangements of the screens and anodes embodying this invention are shown in Figs. 2-5. In all these arrangements the working anode A 'is separated from the auxiliary anode HA by a screen grid SG, the working anode A being always arranged behind the auxiliary anode HA, if viewed in the direction of the ray S t- St'.

If, int-an arrangement suchzaslshownin;-Eig i 2, th ray enters the critical range,'if the mesh of the screen grid is sufficiently narrow, a change of the anode voltage become imperceptible at the point is.

In order to avoid an exchange of secondary emission with the screenygri-dfSG;agsullpressor grid BG is further inserted ;etwe.en :thefscreen grid SG and the anode A Figi3.

A simplified and yet highly effective arrangement is shown in Fig. 4, where the sa'uxiliary' anode HA and the screen grid sG form a rna 'jallxiliary ano'de, and a grid structure adapted 'to'take upsuhstantial current provided between, and in a plane parallel to the planes of, the two ianodes forzthepurpose of substantially preventing 'anypassage from the working anode to said chanical and electrical unit, in which ,the'surface of the auxiliary anode HA is continued bythe :surface of the screen gridss'Gi, -which maylhave the form of a wire-gauze or may be formed of windings. L'In i consequence of this arrangement the potential is imainlyrdetermined, throughout the ientire i surface-and: therefore also at 5 the criticeilepdintfkg-by: the voltage of th auxiliary anode HA and depends from the anode voltage only in --proportion :to :the passage :from the anode A -throughgtheisuppressongridzBG. 1

I elf-it :should prove cnecjessary, ta :further lscreen .grid L-ISGz can hewinsertedlbetween the auxiliary, --.:ano'de and;th;e suppressor :gri'dLBG :(E'ig. 5.).

1 .Inzzthe "combinations shown in :Eigs. 2,;3-and 5 v{the isoreen i grid SGi 1 can be connected with the auxiliaryanode insid ,orloutsideofiitheivalve.

:the arrangements iaccording to :this ;in-

' mention the :amplificationefactor .of ttheiva'lve can :d iincrea-sed to more j than :20. eHowever, such values are; necessaryisin lordergto attain -amp1i JCfifi-QII factors above 100 and valve resistances 'sahove l0.0,000 ohm,:vincthecase OfoflBOdG currents tahove :limilliampere, which u'ssagain necessary order to: obtainzmutualconductance values above V ,i'IIhe electron .ray valve vthus requippedican be fitted with one or a plurality of control-members G ;inorder ;t o lbe;able to ;use :the svalve'raslamplifier or mixing valve or control waive.

;-I f it: is ;d esi red to;produce Jby .meansto'f an electron ray valve alternating anode .=curre nts of -a magnitude similar to that of ethe usual aspacescha f e controlled-"electron valves, ithe electron ray bundle must bezproduced by meansczof an electrode surface K of 6-1 cm. In that case it i very-useful to iform .the bundle normally to ;-.;the longitudinal axis of :a prismatic :or .cylindric ;?-h0de K and ,to ssubdivide 1it intoetwo :or more v bundles;accordinggtonFJigs.:.6 ancli'7. ,v c

-Qn im syffo 'instance operate by ;.such an arra ement -az= mixing evalve; connection b ;arrang inabehin th c'athnde-K a spaceecharge control 1 i t the .scr emng. system :according J30 i'this I in vention is illustrated .in Figs. 1+7 .only with -referenceeto theicase Where ;the concentration .and

v deflec tign of the celi fitron .raymr zbundle of eleci mmra isefiect that the-same; a easements will :also bringi'forth lelectrostatically, it .is evident z ll fl fi iq sma neticlor mixed i0 {and sdeflesticn. .Qf ithe oelectmn r y deflecting means and any exchange of secondary emission between the two anodes, whereby to ren'derithe electron paths. and-the inner resistance .of the working anode substantially independent i from changes of sthe :anojde tpotential ithrcughout theaange df-ioperation.

22. An electron beam itubecomprising anJelectron remittingcathode, imeans .zfor deflecting .-.the .ele'ctrons,.-and electrodes-disposed. normally to the directionof the electron beam as emitted from -said cathode,including an auxiliary anode, a working :anotie,y.said anodes being arranged in ---c ns.ec11tive :parailel planes, the plane of said :workingan'ode. being'disposed to J the rearv of said auxiliary 2 anode, :and :a a (grid structure adapted to take. up substantial: current provided :between. the ;two anodes :forthepurpose oft'tsubstantiallytpreventing any passage from the working anode to said deflecting means lalld any exchange (of. secondary zemission rbetween the two (anodes, said rid structure .comprising'lal screen .grid attached l.to,;andsdis posed in;the plane of, said auxiliary ,anQde .so as Lto "be. located sin'front of said worksing anode; whereby torender :the electron paths and theinner resistance 01 the working anode s ubstantiallyindependent from changes of the anode potential throughout the range of opera i n.

-" An electron'heam tllbEiOOlIlDliSillg an. elecvtron ie nittingicathode, means for "deflecting the electrons and electrodes;dispcsed normally' to, the ldirectioniof the electron-beam .asemitted from said cathode-including an :auxiliary anode, .a

working anode,rsaid-anodes'ibeing arranged in consecutive :parallel "planes,v ;the plane of said Work n anodeibeins disposed to lthe rear of said to tal:e' :upzsubstantial;;current provided between the two lainodes rorrthe purpose of substantially .ai xiliary anode, land ;a .z -rid structure adapted p even ing any m a e from -.:the workin anode to said deflecting means, and :any exchange .of

G :and then .providinganother deflection Lcontrol v as indicated ;for instance .in Fig.7 -7 'iby rthe rods secondary emission betweemtheitwo ;:an0de.s, said .'.g-. id.- structure zcomprising i a;screen grid: attached to, and diDQS8d in;the plane .of, saidiauxiliary anode so as tobe located-infrontofsaidworking e, a '.-se nd s reen :grid and 'a 'suppression grid arranged in consecutive parallelplanesbevtween, .and in parallel to the planes of, vsaid anodes, z-whereby to renderthe electron pathsand the inner resistance o fthe working -anode;subs a t a lyind pen e t r m: chanses;of:;the anode potential throughout the. range of operation.

7 V H'HF'ERENC-PREISACH.

' VIMRE ZA'KARIAS.

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