US2672573A - Beam shift electron tube - Google Patents

Description

March 16, 1954 p. w CHARTON 2,6725 73 BEAM SHIFT ELECTRON TUBE Filed March 15, 1951 6 Sheets-Sheet l IJHIIJ INVENTOR. PAUL PK CHARTO/V March 1954 P. w. CHARTO N BEAM SHIFT ELECTRON TUBE 6 Sheets-Sheet 2 Filed March 15, 1951 FIG. 5.

FIG. 4.

FIG. 3.

FIG. Z

FIG. 6.

INVENTOR. PAUL w a m/grow BY March 16, 1954 p w CHARTON 2,672,573

BEAM SHIFT ELECTRON TUBE Filed March 15, 1951 6 Sheets-Sheet .5

FIG. 9

INVENTOR.

3404 m CHARTO/V BY A I /jTT RNE) March 16, 1954 P. w. CHARTON BEAM SHIFT ELECTRON TUBE 6 Sheets-Sheet 4 Filed March 15, 1951 FIG.

FIG. l3.

am: 505- hr J 1/4 an N INVENTOR.

PAUL W CHARTO/V March 1954 P. w. CHARTON BEAM SHIFT ELECTRON TUBE 6 Shets-Sheet 5 Filed March 15, 1951 FIG. l4.

III lllllnlll lll I I z I II FIG.

FIG.

FIG. l7.

INVENTOR. PAUL W. CHARTOIV 7 BY i A77 NE) March 1954 P. w. CHARTON Bl'EAM SHIFT ELECTRON TUBE 6 Sheets-Sheet 6 Filed March 15, 1951 FIG. l8.

FIG.

2 INVENTOR.

49 PAUL m CHARTON BY A7 R/VE) Patented Mar. 16, 1954 BEAM, SHIFT ELECTRON TUBET Paul iM-Charton; Montclain: N'. *J.,1.assignr:to.-.

National Union Radio Corporation, .0range,;. N; J a corporation of Delaware;--;;

Application March"15, 1951, Serial No; 215,699 j 17 Claims.- (01. 315-11-12);

This invention relates tcelectron tubes, and s having an velectrode arrayrcr controllably shift:

me an electronbeamalong a path which extends parallel to the length oi an electron-emitting cathode, while restricting the efiective area of hecathode t a localiz dre n cfrt c th d Another, o j ct is o p ovide, a ov o antionoi electrodes forccnfiningthe effective emitting ..area, ofla cathode to a signal-controlled;

shiftable localized, portion of the cathode surface. nother object is to proyideea nqvel method.

b. 7., 8 I I n% atareet o .se iespi't e t withia localized electronbeam.

n th r obiectis to. provid ia ovel. rm.,.0 cathodeeray tube for subjecting an electronbeam, wozdim nsional mov ment. .o era .a satq be'scanned.

A furthe object relates to anfleleotron tube having, a novel combination of elements for cause.

ing, angelectron beam to be controllably shifted inv threernutually perpendicular relations.

Another object is to prcvidea novel,,forrn of electron tube of the beam-stepping kind;

andc,organization. of electrodes in an electron.

A feature ofjthe inyenticn relates to.an elec ,V

trontube having a pair of electron beam con;

trolling sections of. mutually opposite variable:

muv characteristics to select a particular portion of the electron beam from a cathode of extended '7 area, and for variably shifting the trajectory termination ofsaid selected portion,

Another feature relates to an electron tube a having'anelectron emitting cathode, in conjunction' with a pair of electron controlsections ofj oppQsite variable-mu characteristics.

Anotherpfeaturerelates 130a cathode-ray tube,

having a fluorescent target which is; mounted "at;

substantially right angles to an elongated j'cathoderand--a'plura1ity'oi variable-mu electrode arraysand magnetic field-producing" means to cause the said-targetto be scanned in a circular-orennular area by electrons emitted from; controllably localized-areas along the length or the cathode.

Another feature "relates to an electrcntube havinga primary-emitter,- a secondary emitter and a collector or target,-in conjunction-With series of variable-mu electrodes-or gridsforcaus-- se target to be scanned by the electrons emitted from; any desired area-of the cathode.

Another feature relates to an electron tube having a series of variable-mu glidSlOCfitGd-{bB tween a primairy-emitting cathode and a target,-' which grids are mounted in predeterminedangular relation and energized so that the target/can be scanned-in anydesired pattern by-suitableenergizaticn of saidgrids.

A further feature-relates to-the novelorgan-- ization, arrangement and relative -1o cation=- and interconnection of parts which cooperate to provide a novel and improved electron tube of-the electron scanning beam type.

Other features and advantages not ;particularly enumerated, wil-l'become apparent after -a; consideration of the following detailed description and the appended claims.

In the drawing,-r vhich shows certain preferredembodiments,

Fig. 1 is an elevational and sectional view of anelectron tubeaccording to the invention.

Fig. 2. is a. plan-sectional view-0f Fig.1, taken along the line 22 thereof.

Figs-3, 4 and 5 are graphs used in explaining the tube of Figs; 1 and 2.

Fig. 6 shows one typical circuit arrangement for energizing the electrodes-ofthe tube of Figs; 1 and 2.

Fig. '7 is a modification of the circuit'arrange ment of Fig.;6.

Fig.- 8'is a perspective and partially broken: away view of the tube of Figs-1 and 2.

Fig. 9' isan elevaticnal View of a cathode-ray tube embodying-features of the invention:

Fig.1!) is-a plan view of the tube-ofFig.-9s

Fig. 11 is a further modification of the inventionemploying a primary emitter and a secondaryemitter.

Fig. 12 is an elevational view ofa further" modification of the inventi0n.-

Fig.:-l3 is a sectional VieWof-Fig. 12,tal;en along the-line I3I 3 thereof; i

Fig. 14 is a perspective view ofenother *modi fic'ationof the inventionrfor producing, coordi nate scanning;

Figw15' 'is'a further-modification of the inven tion 'embodied in-a double coincidence detector.

Fig. 16 shows a still'further embodiment of; the invention embodied in a stepping tube for. producing stepping motion of anelectron beam. 7

Fig. 17*is a graphexplanatory of, the operation Fig. 18 is an enlarged View of the grids of Fig. 16.

Figs. 19 through 25 represent respective additional modifications of the invention.

Referring to Figs. 1 and 2 of the drawing, the numeral It represents any suitable evacuated enclosing bulb or envelope having for example, at one end thereof, the usual press or header H through which the various lead-in and electrode support wires are sealed.

Suitably mounted on the support wire i2 is an electron-emitting cathode I3, which may be of any type well known in the electron tube art. Merely for illustration purposes, this cathode is shown in the drawing as of the indirectly heated type, comprising an elongated thin walled metal sleeve H5 having on the interior thereof an insulated heater wire I5. Surrounding the cathode I3 and supported on the usual grid side rods [6, I1, is a wire wound grid it such as is well known in the electron tube art. This grid is of the variable-mu type, that is, the individual turns or grid laterals are spaced apart unevenly along the length of the grid. For example, as shown in Fig. 1, the turns or laterals which surround the upper end of the cathode !3, are relatively closely spaced, and the spacing between successive laterals increase towards the lower end of the cathode. Preferably, the spacings of successive grid laterals vary in accordance with a predetermined law. For example, this spacing may increase in an exponential manner. It will be understood, however, that the invention is not limited to any particular spacing sequence. The action of such variable-mu grids in controlling the cut-off of the plate current of an electron tube in accordance with the voltage applied to the grid, is well known in the art, and for a detailed explanation thereof, reference may be had to Radio En ineering by F. E. Terman, published by McGraw-Hill Book Company, Inc, New York, N. Y., First Edition, page 355. Also surrounding the cathode I3 is an additional variable-mu grid l9 having the grid laterals wound around or supported on the respective grid side rods 20, 2|.

In accordance with one phase of the invention, the grid H] has its grid laterals spaced apart in a manner which is a reverse of the spacing of the grid laterals of grid i8. Thus, as shown in Fig. 1, the grid laterals of grid 9 adjacent the upper end of the cathode it, are widely spaced and this spacing decreases towards the lower end of the cathode. Preferably, although not necessarily, the grids E9 and I8 surround each other in relatively close relation as compared with the spacing between the grids and the various succeeding electrodes, such for example as the anodes 22.

As shown in Fig. 1, the grids are surrounded by a series of short cylindrical metal plates or anodes 22, which are spaced or insulated from each other and each of which may be provided with a separate lead-in wire 23. It will be understood, of course, that if desired, a well-known suppressor grid and screen grid may be interposed between the variablemu grid 59 and the anodes. It will also be understood that for certain applications, instead of us ng a series of separate anodes 22, a sin le continuous anode may be provided. Furthermore, while the tube shown in Figs. 1 and 2 has the eectrodes in the form of tubular or cvlindrical ele'nents, this is not necessary. For example, the grids i8 and I9 may be single planar elements mounted in parallel planar array with a corresponding series of planar anodes or plates, and if desired these anodes and plates may be coated with suitable fluorescent material, which fluoresces visibly in response to electron bombardment. The variable-mu grid i8 is provided with its respective lead-in 24, and the variable-mu grid 19 is also provided with its respective lead-in 25.

Fig. 6 shows in schematic form, a typical manner of connecting the various electrodes of Figs. 1 and 2 in circuit to achieve the objects of the invention. The elements of Fig. 6 which are identical with those of Fig. 1, bear the same designation numerals. Thus as shown in Fig. 6, the electron-emitting cathode i3 is connected through a suitable adjustable bias circuit, comprisin for example the potentiometer 26 and the direct current bias source El; the negative terminal of this bias source being connected through resistor 28 to the variable-mu control grid i8. Likewise, the second variable-mu grid is is connected through resistance 29, and thence through the potentiometer-bias elements 26, 21, to the cathode it. In order to adjust the relative direct current bias on the grid 9 with respect to the grid it, the resistances and 29 have bridged thereacross, another adjustable potentiometer resistor 38, whose adjustable arm 3i is connected directly to the grid Hi. The center point of resistor as is directly connected to the grid IS. A suitable direct current source 32 is connected across resistor 36 with the polarity as indicated. By this arrangement it is possible to vary in any desired manner the direct current bias potential on grid l8 and on grid l9.

Since the grids I8 and I9 each have a variable pitch winding or variable-mu control characteristic, as the bias applied to each is made to vary, for example by adjusting the potentiometer arms 3| and 33, the cut-01f point for the flow of plate current to the anodes 22 travels linearly along the length of the cathode 13. In other words, considering the cathode i3 and the first grid It, for very high negative potentials the electrons from the cathode flow through the grid only at the more open or wider spaced regions of that grid. Therefore, by reducing this negative direct current bias from its maximum to a lower negative bias, the effective length of the cathode I3, so far as emission through the grid [8 is concerned, can be made to vary linear- 1y with the direct current bias applied to grid i3. Likewise, with respect to grid IQ, for a predetermned maximum negative bias on that grid, electrons from the cathode will pass through grid i9 only at the open or wide spacing end thereof, but as this negative bias is reduced in magnitude, successively greater areas along the length of the cathode E3 become effective in emitting electrons through the grid l9. Therefore the windings or spacings of the grid laterals of the two grids I8 and I9, can be so arranged that there is only a small open overlap of the two effective sections of the cathode controlled respectively by each of the two variable-mu grids. In other words, the two grids are both electronically open to simultaneously pass electrons to the anode or anodes only over a small portion of the cathode, the size 0 and location of which portion varies with the relative potentials applied to the grids l8 and 59. This relation is roughly and diagrammatically illustrated in Figs. 3, 4 and 5.

In Fig. 3, the abscissae represent the successive magnitude of voltages applied to grid l8,

meta-Feas resent the corresponding relation betweenthe voltagesapplied to grid I9 and the-corresponding effective emittinglength of the cathode '13,

so'far as electrons passing-to the anode: are con- 1 cerned. Fig. 5 shows the combined result of the simultaneous action'of both grids 18 and l9 in controlling the how of plate current to the anode. or anodes. As-will be seen from Fig'.- 5,

the effective emitting area of the cathode, so-far as electrons. reaching the anode or anodes are i concerned, that isthe overlapping 'open sec-- tions of both grids, is relatively narrow and itmoves alongthe length ofthe cathode ina -rel-' atively linear manner. If, therefore, eachofthe anodes 22 is provided with a fiuorescent coa't-- ing, the variationof-the potentials on the grids IB and. I9, will result in the electrons which pass the grid I9 impinging successively upon the said anodes, which impingement will be-indicated by a corresponding fluorescent effect.

Fig. 8 shows inpictorial'perspective form, the position of the electron stream from the cathode forone particular relation of potentials applied to grids I8 and I9.- By reason of the aligmnent of the grid side rods, the electron stream isshadowed by those sid'e rods in a manner well known in the electron tube art, so that the electrons'which pass through the grid 19 are substantially in the form ofian-shaped sheets or streams extending diametrically opposite from thecathode I3 tothe-anode. In the particular relation shown in Fig, 8, these electron sheets byreason of the particular potentials applied to the grids I8 and I9, impinge upon thesecond anode 22, and by varying the relative potentials on the grids l8 and [9, these sheets can be made to travel upwardly and downwardly as indicated by the arrows, thus impinging in succession upon the-respective anodes 22.

It will be understood, of course, that since'the grid 59 is closer to the anodes than'thegrid l8} it may be necessary to adjust the potentials of these grids in such a way as to produce the linear relation illustrated in Fig.5. Thus 'in" Fig. 6, the arms 3| and 33 can be ganged to a common" control member or device 34 -to preserve therequired potential relations. It will be understood,of course, that it is not absolutely necessary that these relationsbe truly linear, since I in any event the combination will result in the production of a sheet or beam 35 of the desired thickness 36 and whose position can be-made to vary linearly alongthe cathode with respect to any desired parameter.

The invention is not limited to the conjoint adjustment of the potentials on the grids l8 and it. These potentials may bemade to vary in-- dependently of each other,-and in fact the'thickness 36 of the beam 35 can be made' to vary 50.. are shown mounted in perpendicular-relationand while its location considered along ;,the length of the cathode is being varied. Thus, it-is possible to control the beam width so that it. can overlap ,two or more adjacent anodes 22.

If .desired, the two grids l8 and I9 canbe excited by alternating current potentials. Thus ing 38 is energized "'from a: suitable:- source: 39 'oli'i signal-controlled alternating current =potentials;:-. The cathodekl3 is returnedto' anradjustable tape. 40 on the secondary winding 31- through aresistor 4|. The tap AB- can be adjusted'so :as to control the-open overlapping electron-passing. 1.: sections of the two-grids I t and I9; thus-in eia fect causingthe electrons to -scan the anode 22 in a direction parallel to the length of the -cathode 13'.-

Figs. Sand-'10 show the-invention embodiedins a two-dimensional scanning-tube. of the cathodeJ-'-- ray type: This -tubemaycomprise a suitable enclosing envelope'dfl having mounted interiorly thereof at one-end; anelectrode-assembly com=- "grids 44 and '45 will travel along the length" of" the cathode 3 to produce-ineffect .a relativelynarrow beam 43. Thus thevertical height of-the beam is controlled by the above mentioned open overlap of-the gridst l 'and and-the width of that beam-is'controll'e'd by thewidt of the-slot d3. Mounted-inth'e path'ofthisbeanr- 48 is any suitable beam--'defiecting- -system,-comprising for example thedateraliy-spaced electrostatic deflector plates Ml and Eitwhich can beenergized in anydesired-manner-to deflect the beam 5-8 in a directiontransverse to its movcment relative tothe-length ofthecathode-43. Suitably mounted within'th'e envelope 2 at the opposite end from the-cathode i-t is a screen ortarget which may comprise a seriesoi discrete elements 5 I carrying any 'well'+known fluorescent 1 material which fiuoresces when. impinged upon by the electron-beam it; Thus it is possible to subject the beam 33 to any desired two-dimensional scanning movement by appropriate em ergization of the grids 3 2, 25, and of the-plates 39 and 58-.

As pointed outabove, it isnot'necessary that the two opposite variable-mu grids be mounted in" parallel array. Thus in- Fig.- 11 these grids cooperating with" a secondary emission' surface. Thus inFig. 11- the primary electron-emitting:- cathode 56 may be similar tothe cathodei3 and may have mounted adjacent "one sidethere-- "of a planar control grid havingthe gridwires or laterals spaced apart successively greater dis--- tances considered from one-end of thecathode' to the other. Mounted in inclined relation-to the cathode 51' is a secondary emission plate or target 53 whichs'has its surface facing the cathode 5! treated ""or coated so as to render'it an efficient' emitter of secondary electrons when bombarded. by primary electrons from cathode 5-H.

,Mounted in spaced relation to the target 53", "and for example at right angles to thecath'ode 5 i' ,is another variable-mu control grid t ihav-ingg" the grid laterals successively spaced unequally to" provide the desired variable-nu characteristic.

Mounted-in spaced-relation to the opposite side of grid 54 is a suitable electron collector plate'55" which collects the secondary electrons that pass through the grid 54. By mounting the grids wand" 54 with their fine mesh portions adjacent as,

;shown,.it.is. clear that the .gridti! when, it re.-.

ceives a potential of a certain magnitude, permits the primary electrons from cathode to pass therethrough from a relatively restricted portion along the length of that cathode as indicated by the shaded area. Likewise, the beam 56 of secondary electrons will have a corresponding width. However, because of the variablemu or cut-oil characteristic of the grid 54, only a portion of the width of the beam 55; is able to pass through the appropriate mesh of the grid 54 to reach the collector 55. Thus by varying the relative potentials on the grids 52 and 54, the section 5'! of the beam 5% can be made to move across the target 55 as indicated by the arrows. The manner of connecting the oathode 5P, the grids 52, 56, and the target 53 in circuit, may be the same as that shown in connection with Figs. 6 and 7. The collector 55 will of course be connected to a suitable load circuit 58 and to a suitable positive direct cur-- rent biasing potential 59.

Referring to Figs. 12 and 13, there is shown a further modification of the invention, wherein the beam can be subjected to controlled motion in three mutually perpendicular directions. In these figures, the parts which are the same as those of Figs. 1 and 2, bear the same designation numerals. They include the central electron-emitting cathode IS, the first variable-mu control grid I8, and the second variable-mu control grid I9. The anode 22 may be in the form of a single continuous metal cylinder. Suitably mounted at the upper end of the described electrodes is a circular disc as which may be coated with fluorescent material. This disc may, for example, be of mica or other transparent material having the fluorescent coating thereon on the surface facing the electrode assembly. Eurrounding the envelope or bulb I8 is a series of excitation coils GI, 62, $3, 6d, which can be connected to a polyphase alternating current supply, so as to produce a rotating electromagnetic field whose axis of rotation is along the length of the cathode it. Mounted adjacent the lower end of the bulb is another coil 65 for producing an electromagnetic field extending through the tube parallel to the length of the cathode l3. As a result of the combined rotary field and the longitudinal field acting on the electrons from the cathode i3, and as a result of the selective opening effect of the two variable-mu grids l8, I9 as above described, the beam which reaches the surface 66 can be given a rotary motion as indicated by the arrows in Fig. 13, and the termination of this beam at disc iii; can be varied in a radial distance outwardly from the center thereof. In other words, when the grids i8 and [9 are relatively energized so that only a restriated region at the upper end of the cathode I 3 is eiTective, the selected beam trajectory passing through the overlapped open sections of the two variable-mu grids terminates at the disc 5 near the center thereof, and at the same time can be given a rotary motion. On the other hand when the potentials of the grids l8 and is are adjusted so that the efiective beam is that leaving lower regions of the cathode it, this beam strikes the surface 69 at a correspondingly further distance from the center thereof, and likewise can be given a rotary motion. This arrangement therefore provides a convenient meth- 0d of producing fluorescent traces in polar coordinate fashion. For example, the radial distance of the fluorescent spot appearing on the disc 60 considered from the center thereof, can represent one coordinate such as distance, and

8 the circumferential position of that spot considered around the center of the disc 60 can represent angular position or azimuth. It will be understood, of course, that the windings M4 can be energized at a fixed rate of speed, and if desired an additional grid 66 can be mounted between the above-described electrodes and the disc 68, and this grid 68 can be energized with suitable blanking pulses or the like so as to cut off the beam striking the disc 83 except when received signals are to be displayed on that disc.

Fig. 14 shows, in perspective diagrammatic form, a further modification of the invention, and wherein the elements which are the same as those of Figs. 1 and 2, bear the same designation numerals. Thus the electron emitting cathode l3 is provided with a pair of oppositely-directed variable-mu control grids l8, 19, whose grid laterals 51, 68, may extend perpendicular to the length of the cathode !3. Between the grid I9 and the fluorescent target or anode 22, there is mounted another pair of variable-mu grids E59, iii. However the grids 5t and 10 have their grid laterals ll, l2, disposed at right angles to the laterals 6'5, 88'. Here again, however, the laterals of grid 59 are spaced unevenly from one side of the grid to the other, and likewise the laterals of grid it are spaced unequally from one side to the other of that grid but with the opposite relation of spacing as compared with the spacing of the laterals of grid 69. Consequently, by suitably energizing the grids I8 and it as above described, there is produced in effect a beam or sheet 35 which moves vertically along the length of the cathode. In a similar manner, by suitable energization of the grids 69 and 10, the sheet which passes grid I9 is further subdivided in a horizontal direction, that is, a direction perpendicular to the length of the cathode, so that in effect the target or anode 22 can be scanned by an electron spot, and this spot can be given any desired coordinate movement or pattern of trace over the surface of target 22. It will be understood, of course, that the showing of Fig. 14 is schematic and that the various electrodes are supported in any conventional manner within an evacuated envelope or bulb which is omitted from Fig. 14 for purposes of clarity.

Fig. 15 shows a still further modification, wherein the invention is embodied in a double coincidence detector or gating tube. In this embodiment, there is provided the cathode I3 and the oppositely-directed variable-mu grids l8, I9, above described. In addition, another set of variable-mu grids l3, i4, is provided, these latter grids having oppositely-directed variable-mu characteristics. For example, the grid 73 may have its laterals spaced unevenly, or to produce a variable-mu effect similar to that produced by grid l8; whereas grid i has its laterals spaced to produce a variable-mu effect similar to that of grid iii. Consequently, in order to have any output at the anode 2%, it is necessary that the signals applied from the source 75 and the signals applied from the source EB, be coincident in time and adequate in magnitude.

As pointed out hereinabove, the invention is not limited to any special law of variation of spacing of the variable-mu grid laterals of each pair of grids, so long as the openness of their respective meshes varies in opposite considered along the length of the cathode. However it is possible with certain predetermined spacings to achieve speical results. Thus instead of the spacringrbetweenthes successive.flateralsrotz a grid: vary- Iingazprogressively; these laterals cfitheigrid :may :be 'arrangedrin groupsiandiwmay' (be usedtopro- 'vide an :improved iorrnioiii stepping tube. Thus as shown in. Fig.. 1 6, "the: evacuated Ibulb i'i"en closes an elongated electron-emitting cathodefli land za series 'of ia-nodes' or targets I "i9. interposed between thecathode' andianodesis a first variable-mu'igrid G8 which hasits grid laterals. ar-

ranged in groups withi thei spacingibetween the individual laterals of any given group eciual, but with the interlateral spacing *in successive groups :01? increasing-openness or mesh. Likewise the second variable-hm gridi ili rha-s iitstllaterals arranged in groups-with the interlateralcspacing :for' any givengroup equaljfbut with the "interlateral-spacing iii-successive gror. progressive- ;lyincreasing. 'Thesetwo grids are mountedxso that the progression of thei'mesh in'one grid fierctendsin the'opposite direction to the'progression or the mesh in theiotherg'rid, the relation of the twor'grids being-rmore clearly-illustrated in the -m'a'gnified 'viewofFig. 18.

By applying increasing .=potentials to the grids "80' andti, for 'exampleby'movingthe contactJ arms 3 i, 33; the electrons from successive'regions -of the cathode along its length will be selectively passed insuccession to the corresponding anodes 19, as indicated by the arrows in Fig. 16. While 'Fig. 16 shows'a'seriesiof beams striking the retspective anodes; it"will be understood that Ior any :given energization of the. grids and 85, only one'such 'beam' wi11 arrive at the corresponding 1 anode. Fig. 1'7 shows in'composite chart and graph form, the relation between the two grids and the-blanking on'and off of the beam in successive steps i as it moves from. one anode to another.

Since the invention is concerned broadly with the provision ofi'a tube having .at least two suc- =cessive variable-mu sections, it"will be understood that the two overlapping variable-mu effects can be achieved-by other well-knownmeans. For example; instead of using two successive variable-mu wire-wound grids, one such gridimay be used, and the cathode itself may be coated along its length in a variable manner. Thus as shown in Fig. 19, the-cathode '82 is coated so that the thickness or diameter of the coating decreases from the upper end to the lower end. The grid G3 will then be a variable-mu grid with its closer 'meshadjacent the upper end of the cathode, and this mesh increasing in openness towards the 'lower'end of the cathode. With the arrange- ."ment of Fig. 19, the electron beam will move downwardly from the top to the bottom of plate -84 vasthe direct current plate potential is increased from a lower positive value to a higher positive value, while the grid potential is simultaneously varied from a less negative to a more negative value.

Fig. 20 shows another embodiment wherein the cathode is uniformly coated along its length, but'is'inclined with respect to the'variable-mu grid this gric having its closer spaced mesh,

adjacent the nearer part of the cathode 85 so that the'spa'cing between the cathode 85 and the grid 8% in relation to the openness of the grid mesh. Thus byimpressing suitable potentials on the grid 82%, electrons'from corresponding localized areas of the cathode 85 will impinge upon the anode It'will be understood, of course, that the inv'entionis not li'niited to the use-of wire-wound grids. For example as -.shown..=in Eig.' 21,-the

adjacent 'the'upper end-of the cathodeanduts nally varying thickness. similarly constructed, but mounted in ,the re- :verse sensewith. respect to grid 95.

' spacing.

cathode" 88" has associated; therewithrtwo' control :gridsjfiii, iiiliand; an anode 91. .89 has a. tapered slot -92,;andlikewise the gridsilil has a reverselypositionedtapered slot-93,thus providing the .required successive variable-mu The control grid eiiects so that when the grids 89 and on are energized as explained iii-connection with Fig. 6 orFig. 7, the electrons fromcorresponding localized regions along the length of cathoderlm strike the anode 9|.

If desired, the variable-mu effect may .be

achieved both by a variation of the openness'of the grid wire mesh, and also by a variation in the thickness or" the said Wiremesh. Thus *as shown in :Fig. '22, the cathodeflfl has associated therewith variableanu grids 95,- 96, and anode iii. The grid laterals of grid -are progressively spaced apart, and these laterals are also of grad- The grid '95 may i be Instead of using variable-:mu'gri'ds with:paral lel grid'side rodsiandwith the grid laterals. of

from various regions aalong the length of :the cathode 98.

Fig. 24 shows a still further modification wherein the cathode 1.05. and: the plate. or -:anode i d t are concentricand substantially cylindrical,

whereas'the first grid i ill-is of the variable -.wind'- ing pitch type and is also.- of conical shapeuvith the narrow end of the cone adj acent. the-top (of the cathode 435 and the wider-endc-of-thevcone adjacent the lowerendvof the cathode. -On the tether-hand, the-second-grid w N33. is also of -the variable winding :pi-tch typea-nd isalso of conical shape butwith the narrowrend of theconeadjavcent thelower end ofithe cathode'andthe'wider end of the-coneadjacent the :upper endof-the cathode. grids ml, ltd, -;as illustrated"in-Fig.1 6ror- Eig.i7,

Thus, by varying thelpotentials on the the desired steppingaction of the electron :beam

along the length of. the .plate: I as can be effected.

It not: necessary thatc-the individual: turns .of

the-grids 167- and H38 be 10f. variable lwinding pitch, thatis-with different-spacingsbetweensuccessive-turns. If desired,- each ofthese grids HIT, l may. be-of uniform winding pitchsince the mu :of: the first-grid Whatsuccessive-devels,

varies withthe distance .between'the. two. grids H23, and the mu of the .-second,grid I08 likewise varies-with-its distance to the anode l 05 at successive levels.

Fig. 25' shows -.a still further modification wherein the cathode -i os'and-the anode .or-plate HQ are coaxialand of simple -cylindrical-1form. In this embodiment 'the'inner-grid l l loan-be of uniform pitch and". of cylindrical form: that. is of uniform" diameter-"along :the lengthsoi the oathode. (3n the 'otherhand," the second grid H2 can be of conical form and with; its--wider1end lower end adjacent the lower end of the, cathode. Here again, the variable mu efifectof the; grid 1 I I :at' any givenc-leveliisr'determined loyrithe variable spacing between grids i l hand i l 2;; and the-rari- 1 l able-mu effect of the grid H2 at any given level is a function of the spacing between that grid and the anode H at any given level. If desired of course, either or both of the grids I [I and l 12 can be of variable-mu or progressively variable winding pitch.

What is claimed is:

1. An electron tube, comprising an evacuated envelope enclosing an elongated electron-emitting cathcde, a first variable-mu electrode having a series of openings of progressively different size with the openings disposed along the length of the cathode, a second variable-mu electrode also having a series of openings of progressively different size and extending along the length of the cathode, the said first electrode being mounted with its openings decreasing progressively in size considered from one end of the cathode to the other, and the said second electrode being mounted with its openings increasing progressively in size considered along the opposite direction of the length of said cathode.

2. Electron tube apparatus, comprising an evacuated envelope enclosing an elongated electron-emitting cathode, anode means for said cathode, and means to scan said anode means with an electron beam emanating from any desired section along the length of the cathode, the last-mentioned means including a source of variable voltage, and a pair of variable-mu control electrodes each connected to said source, said electrodes having respectively oppositely-directed variable-mu characteristics considered along the length of the cathode, with the said characteristics progressively varying along the electrode length.

3. An electron tube, comprising an evacuated envelope enclosing an elongated electron emitting cathode, anode means for said cathode, at least one variable-mu grid located between the cathode and the anode, said grid having a progressively coarser mesh along its length, said cathode being inclined toward said grid with the closer end of the cathode adjacent that portion of the grid having the finer mesh.

4. Electron tube apparatus, comprising an evacuated envelope enclosing an elongated electron-emitting cathode. first and second variablemu control grids surrounding said cathode said grids having their grid laterals arranged to form the electrons into a disc-like beam, one of said grids having its laterals of progressively increasing spacing from one end to the other end of the cathode, the other of said grids having its laterals of progressively decreasing spacing from said one end of the cathode to said other end of th oathode, and means to apply respective control potentials to said grids to cause said beam selectively to shift to any desired region along the length of said cathode.

5. Electron tube apparatus according to claim 4, in which a plurality of target elements are mounted in spaced array along the length of said cathode and successively scanned by said beam in response to said control potentials.

6. Electron tube apparatus, comprising an evacuated envelope having an electron-emitting cathode, anode means for said cathode, first grid means for cutting off electron flow from said cathode to said anode means, second grid means for cutting ofi electron flow from said cathode to said anode means, said first grid means having a progressively increasing cut-ofi effect considered in on direction along the cathode, the

other grid means having a progressively decreas- 12 ing cut-off effect considered in said one direction along the cathode, and means to apply control potentials simultaneously to said grids to cause the electrons from the cathode to impinge upon said anode means in any desired localized region thereof.

'7. Electron tube apparatus according to claim 6, in which said anode means comprises a series of target elements mounted in spaced array along the length of the cathode, each of said grids being wire wound to form the electrons which pass the second grid into a sheet-like beam.

8. Electron tube apparatus, comprising an evacuated enclosing envelope, an electron emitting cathode, anode means ior said cathode, said anode means comprising a plurality of targets to be scanned by an electron beam, said cathode constituting one of the electrodes of an electron gun for developing said beam, a pair of variablemu electrodes having respective opposite variable-mu characteristics considered along one dimension of the cathode and each variable-mu electrode having a progressively varying variablemu characteristic along its length, means including a source of variable voltages connected to said variable-nu electrodes to cause said beam to scan said targets in one direction, and separate beam deflector means to cause said beam to scan said targets in a different direction.

9. Electron tube apparatus according to claim 8 in which said cathode is of elongated shape and said variable-nip. electrodes and said variable voltage source cut-cit said beam from reaching said targets except in a region corresponding to a desired localized portion along the length of the cathode, said separate beam deflecting means deflecting the non-cutoff portion of the beam in a direction transverse to the length oi the cathode.

10. Electron tube apparatus according to claim 8 in which each of said variable-mu electrodes is a variable-mu control grid, the said grids being respectively of progressively varying mesh along their lengths and with the coarse mesh of one grid in registry with the fine mesh of the other grid.

11. An electron tube, comprising primary electron emitter, a secondary electron emitter, target a first variable-mu electrode located between said emitters, and a second variable-"nu electrode located between so secondary emitter and said target for subjectin said target to scanning by electrons derived from any selected portion along the length of emitter.

12. Electron tube apparatus, comprising an elongated electron-emitting cathode, anode means for said cathode, means including first and second variable-mu grids and a source of variable voltages connected to said grids to exert a variable-mu control on the electrons from the cathode to produce a beam which emanates substantially radially from an desired section along the length or" the cathode -n accordance with said variable potentials, signal controlled electric field means to deflect said beam in a direction parallel to the lcgnth of the cathode, and other electric field means to cause deflected beam to rotate around a longitudinal axis of said cathode.

13. Electron tube apparatus according to claim 12, in which a lurni escent target is mounted in concentric relation to said cathode at one end the "cor", and is in successive circular paths of increasing radius under con '"l of said variablecnu means and both said field means.

14. Electron tube apparatus, comprising a central linear cathode, anode means surrounding said cathode, a first variable-mu grid surrounding the cathode, a second variable-mu grid surrounding the cathode, target means concentrically mounted adjacent one end of the cathode, means to simultaneously energize said control grids by respective potentials to select a particular region of the cathode to be effective in producing an electron beam terminating at said target means, and field producing means to deflect said beam radially outward from the center of the target and for rotating the beam concentrically around the target.

15. An electron tube, comprising an elongated cathode, target means to be scanned by electrons from the cathode, a first variable-mu beam control electrode having a progressively increasing mu along its length, a second variable-mu beam control electrode having a progressively decreasing mu along its length, said grids being mounted With one grid having an increasing mu from the top to the bottom of the cathode, the other grid being mounted to have a decreasing mu from the top to the bottom of the cathode both of said electrodes being located between the cathode and target and energized to subject the electrons from the cathode to a series of successive variable-mu cut-ofi effects and thereby to cause said target to be scanned, at any desired localized area thereof.

16. An electron tube according to claim 15, in which the first variable-mu means comprises a pair of variable-mu grids of the unevenly-spaced grid lateral type, said pair of grids being mounted with the coarse-spaced laterals of one grid in registry with the fine-spaced grid laterals of the other grid and with the grid laterals of both grids extending transverse to the length of the oathode; said second variable-mu means comprising another pair of variable-mu grids of the unevenly-spaced grid lateral type with the coarselyspaced grid laterals of one grid in registry With the finely-spaced grid laterals of the other grid,

14 the grid laterals of both of said second pair of grids being mounted substantially parallel to the length of the cathode.

17. Electron tube apparatus, comprising an evacuated envelope enclosing an electron-emitting cathode, a series of target electrodes mounted in spaced array along the length of the cathode, a first variable-mu grid having its mu progressively increasing along its length, a second variable-mu grid having its mu progressively decreasing along its length, both of said grids being located between the cathode and targets, said. grids being mounted with the coarse mesh 01 one grid in registry with the fine mesh of the other grid, the meshes of both grids being correlated so that for successive increments of control potentials applied to both grids the electrons from the cathode are formed into a beam which successively scans said targets.

PAUL W. CHARTON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,452,386 Hartley July 16, 1925 2,031,137 Steimel Feb. 18, 1936 2,041,904 Cone May 26, 1936 2,048,224 Snow July 21, 1936 2,048,228 Snow July 21, 1936 2,043,229 Snow July 21, 1936 2,048,230 Snow July 21, 1936 2,048,232 Snow July 21, 1936 2,075,202 Jonker Mar. 30, 1937 2,090,318 Miller Aug. 1'7, 1937 2,092,893 Snow Sept. 14, 1937 2,113,395 Braden Apr. 5, 1938 2,235,498 Herold Mar. 18, 1941 2,340,594 Junker Feb. 1, 1944 2,460,062 Charton Jan. 25, 1949 2,492,643 Ishler Dec. 27, 1949

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