US2455851A - Improved electrode and envelope structure for electric discharge devices - Google Patents

Description

'Dec. 7, 1948 J. E. BEGGS IMPROVED ELECTRODE AND ENVELOPE STRUCTURE FOR ELECTRIC DISCHARGE DEVICES Filed March 1 1946 Pi 3. I.

6 29 H C 7 x 4 w 2 v Z a I L m M U, will m 9 m w /////1 M l 5 w lhvefitorz. I James E. Beggs,

His Attorney.

Patented Dec. 7, 1948 v calico; I "OFFICE v I IMPROVED Emer enc AN D ENVELOPE STRUCTURE Fort ELEQTRIC DISCHARGE DEVICES James E. Begg's'; Schenectady, N Y..,- assi'gnor to General Electr C mp ny. a c rporati n of New York Application March 1, 194'6,Serial No. 651,223;-

-My -1ttemoa' relates to" electric: discharge: de-

vicesand particularlyto improvemeritsvv in-is-uch devices which are operable over. a widerange of frequencies in .connectionwith either wire or cavity circuits. .t H a i In recent years there have beemmany improve ments inrthe design ofelectri-csdischarge devices, particularly with reference: to the upper limit; of operating frequency, and to improvements in the operating characteristics at the higher. frequencies. Many of the improvements have related particularly to discharge devices for use in what has been known:(is-grounded grid or grid return circuits. In accordance-with my v invention, I provide new and improved electric; dis- 3;

' form.- Asillustrated in the; drawing, the base or I :olurality f leadein conductors are sealed a; new and improved electric discharge device I which is readily operated in either wire or cavity circuits; v I g his a still furtherobjectof myinvention to provide electric discharge devices having desirable operating characteristics at high frequencies; and which is at the same timereadily manutactured bymass production methods and which may be employed in connectionwith standard types of of a portion of the device of; 1 g.1-;il1ustratin-a"a step in theassembly .of the device; 3 1822,

plan view; showing the relation of the": control-grid to, the cathodeof the device, and Fig. 421s: anelevational View, in-v section, v of a: modification ;of my invention. 1 i

- Referring now to the drawing, I.haveshown" my invention embodied in 'an electric discharge devic'eahaving a base; rwhich is adapted toi bc through thearm'nlar ring 4 to provide contact prongs t torthe. device and power supply .c'onnea trons: for: certain of the electrodes. The header is completed by a body on glass ti sealedto the interiomofthe:cylindrical leald-i n conductor 3 and a lead in' conductor 1' which is supported centrails" withinthe conductor-i 3 will be brought out :ata later point the specification, the conductor f provides a leadin and su port forthe control grid .ofthe device. Theheader assembly tmay to adt/antagebe manuractiired in accordance with the method described and claimed in my application Ser. No. 651,233, filed concurrently herewititand assigned tc the ass-ignee -of this application. s e, e

t: The envelope of the device includes-gin addition to the header-l; a generallyicylindrical' metal enclosure! having aninwardly directed flange Elat its-uppe1 end; The anode Al I" ofqth'e device is: supported fromthe flange Bby ahon cw domelike: insulator I 2 having. aeiicuiarercss-Search which-is sealed 'at one end tc-the'flange 9. The anode is'supported in alinementwith the ripper end of the cylindrical lead-lit conductor 3- which also provi d'es a support for the" cathode stmeture v of the device. rig-illustratedin: the drawing,- the cathode is provided annularsheet metal member 1 4% of U ahape:cross section which is supported: in inverted relation from the upper end ofithe lead-i1 1- conductor3 by a sleeve #5- ofthin metal. sleeve-may totadvanta'ge be formed of a 'n ietal foil which has relatively good elec trical conductivity and which; because of its small cross section-conducts relatively small amounts 'of heat: from the cathode structure to the lead-in sleeve 3-. The-sleeve i 5 is bonded to the upper: end-oi the conductor 3 and to the member' tt." The cathode" is heated by aheater element I 6 1 positibhedwi'thinthe" channel of the member'v-M: and insulated therefromby suitable materialsii'ch as: ammimt. It desire'dtthe heater element a be retained: in position by smart tabs (not shownhfbrmed integrally with the member ll .*"I he-=terminal conductors F1 and I-B of the heater are connected with two of the lead in' eonducto'r's 52 *It' Will -be understood that the upper surface of the' cathode' member it is coated with received inIaminiatur'esocket or commercial .55 anielectron emission enhancingmaterialsubh as 3 may be produced from alkaline earth compounds in accordance with methods generally known in the art.

External connections with the cathode are also provided by an apertured disk or washer IQ of conducting material and of larger diameter than the cathode which is supported within the envelope near the plane of the upper surface of the cathode by a plurality (preferably 3) of lead-in conductors 20 and only one of which is visible in Fig. 1. It is apparent that only one of theconductors so employed for supporting the disk 19 needs to extend through the header. As illustrated in the drawing, these conductors are extensions of the contact prongs 5 and are bent outwardly at their upper ends to provide a support for the washer I9. The washer I9 is connected electrically with the cathode I4 by a foil member 2| which may take the form of a plurality of tabs or, as illustrated, may be a continuous Washer. The washer I9 provides an intermediate part of a direct current circuit between the cathode l4 and the lead-in conductors 20. The washer [9 also provides a part of a high frequency circuit between the cathode l4 and the flange 9 of the member 8. As illustrated in the drawing, the member I9 is spaced from the flange 9 by an appropriate distance for the accommodation of a plurality of control members or grids 22 and 23 which are adapted to operate at the same high frequency potential as the cathode. The grids 22 and 23 are of the planar type and each includes acentral portion of fine mesh connected respectively with suitable supporting washers 24 and 25 which are mutually insulated by an insulating spacing washer 26. In a similar manner, the grid washer 24 is insulated from the flange 9 by a washer 21, and the grid washer 25 is insulated from the conducting Washer l9 by an insulatin washer 28. The grid 23 may function as a screen grid and is adapted to be con nected to a suitable source of direct current voltage by a conductor 29 joined at one end to the supporting washer 25 and at the other end to one of the lead-in conductors 5. The grid 22 may function as a suppressor grid and is connected directly with the cathode of the device by one or more conductors 30 connected between the supporting washer 24 of the suppressor grid and some portion of the conductive structure which isat cathode potential, for example one of the lead-in conductors 20. It will be apparent that the screen and suppressor grids are connected with the cathode, as far as high frequency currents are concerned, by the by-pass capacitors provided by the conducting washers I9, 24 and 25 and the insulating spacers 26, 27 and 28. It will also be appreciated that the by-pass connection is closer to the emitting surface of the cathode than is possible with conventional tube structures.

In accordance with an important feature of the present invention, the control grid is completely shielded from the anode and the other conductors by means of the cathode structure. To this end, the control member or grid 3| is supported from the lead-in conductor 1 which is positioned within the hollow cylindrical lead-in conductor 3 of the cathode. The control member is secured to the upper end of a flanged eyelet 32 which is, in turn, supported on the upper end of the lead-in conductor 1. The outer portion of the grid'overhangs the active surface of the cathode as indicated in Figs. 1 and 3. The manner in which the desired grid-cathode spacing is obtained with the structure just described will be better understood 4 by reference to Fig. 2 in which the parts are shownat an intermediate stage in the assembly. After the member l9 has been secured to the supporting lead-in conductors 20, the grid is positioned by positioning the supporting eyelet 32 on the lead-in conductor 1 so that the grid lies against the upper surface of a pair of flat generally semi-circular shims 33 having a thickness equal to the desired grid-cathode spacing, and which are supported on the washer l9. After the grid supporting eyelet has been bonded to the grid lead-in conductor, the cathode assembly, including sleeve l5, which has previously been slipped over the upper end of the cathode supporting cylinder 3, is moved upwardly until the upper surface of the cathode engages the lower face of the shims 33 as shown in dotted lines in Fig. 2. The cathode structure is then secured in fixed relation to the mount by welding together the lower end of the sleeve l5 and the cathode lead-in cylinder 3. The shims 33 are then removed leaving the overhanging portion of the grip spaced from the cathode by the thickness of the shims. The screen and suppressor grids and spacers are then assembled on the ring l9 and the envelope slipped over the assembled electrodes and the tube completed in accordance with processes well understood by those skilled in the art. As illustrated in the drawing, the lower end of member 8 is received in the channel of member 2 and bonded thereto by a body of solder 34.

It will be apparent from the foregoing description that the grid lead I is surrounded by the cathode supporting conductor 3 and is completely shielded from the anode by this conductor. In use, the conductors 3 and I provide a concentric line connection for the grid-cathode or input circuit, and the cylindrical shell 8 of the envelope and the exposed portion of the anode II form connections for a concentric anode-cathode or output circuit. The direct current connections for the cathode, cathode heater and screen grid are readily made with the appropriate contact prongs 5. 7 It is apparent that the direct current circuits and the high frequency circuits are completely isolated when thedevice is used with concentric circuits as described above. The device shown in Figs. 1 and 4 is eight times the actual size of a tube embodying my inventionwhich has been constructed and which flts into a socket having the same dimensions as a commercial miniature socket. It will also be apparent that if it is desired to operate the tube in a conventional wired circuit, the connections may readily be made to the various electrodes without diificulty;

In Fig. 4 is shown a modification of my invention in'which the anode of the device is supported in the interior of a metal envelope and which is not as well suited for operation at extremely high frequencies as the modification of Fig, 1. The device, on the whole, is similar to that shown in Fig. 1 and corresponding parts have been designed by the same reference numerals. In the particular arrangement shown in Fig. 4, the sup- &

Iron ithle washer (to :by suitable :conductors 550f. .s'imilar to therfconductorsm of Fig. '31. IniEigfil 21 havetalsoirrdicated how ran radditional disxch'arge devicennay be lincorporated in the same "envelope. IIn "I the particular embodiment Iillus- "trated a diode lhas been added by positioning san 'iauxiliary/anode 31 iin proximity to the-'outersurf-aceroiithe cathode assemblywhich maybe=coated with an oxide to improve the Electron-remitting qualities (thereof. This :auxiliary anode is supiported from oneof the lead-in conductors 5. .rA's iillustrated, the 'envelope 38 ot the device shown -"in Fig. 4i is r an "op en-ende'd metal cylinder shaving "the ilower en d received in zand rbondeidito i'the ichannel member 2. V 1

iltwvilllbwapparent from theforegoing-descripition tlrat devices embodying-my invention provide exceptionally v complete ish-ielding between 'ithe agrid-icathode an'cl anode-cathode circuitsjthereby sadapting the :device's for reparation in 'cathocl'e :return rcircuits. I The devioes are "equall y well iadapted -"for=use' in conventional circuits at lower frequencies= and f the improved Jstructure -permits their rapid assembly 'by mass production 'methods so that the cost of the devices will not prevent their use :in 'corrventional circuits at lower frequencies.

While I have shown and described particular eembo'diments of my invention,.:it rwill-,be'obvious to those skilled in the artxthatwachanges and modifications may be made without departing from my invention initsbroader aspects, and I, therefore, aim in the appended claims to 'cover all suh changes and-modifications as fall within th'e true spirit and scope or myinvention. *Whatl'Jclaim-as-new =and' desire to-secureby Letters Patent of the United States is:

1. An electric discharge device including an envelope, an anode having a planar active surface supported within said envelope, a cathode structure extending transversely of said envelope and having a planar annular emitting surface surrounding a centrally located aperture, a planar control grid positioned between said cathode structure and the active portion of said anode, a cylindrical conductor sealed through said envelope and joined to said cathode around said aperture, and a support and lead-in conductor for said grid extending through the aperture in said cathode structure.

2. An electric discharge device comprising an envelope, an anode supported from one end of said envelope, a control member supported from the other end of said envelope, a cathode structure positioned on the side of said control member remote from said anode, a metal terminal forming a part of the wall of said envelope between the ends thereof, means connecting said cathode structure with said terminal with respect to high frequency currents, and a conductive cylinder sealed through said other end of said envelope and connected with said cathode.

3. An electric discharge device comprising an envelope, an anode supported from one end of said envelope, a control grid, a conductor supporting said grid from the other end of said envelope, a cathode structure positioned on the side of said control grid remote from said anode, a metal terminal forming a part of the wall of said envelope between the ends thereof, means connecting said cathode structure with said ter-'- minal with respect to high frequency currents, and a hollow conducting structure surrounding said conductor and extending from said envelope "6 -tonnzovitle aisecondiliighirrequency:

rsaiii rcathoder r :4; s'An :electricedischarge :deviceieompri'slngaan *envelopeaaman'ode rand a cathode having: planar activessur faces, a plarrar icontrol @electrode anterzpose'd ibei'twveerr.said rain-ode rand-said "ic'athode, a cylindritatl conductive lstructure sealed tlirough said envelope and isupporting fisaid icathode ra ileadin ncnductor supported: concentrically .within maid :cylinder -:and in insulated relation math respect-theretopsai'd lead-iin:con'ductor providing 1aasuppontdorlsaid coritrol electrode;

.25. rkn-relectric discharge devic'e comprising in :header, an'wannular' :cathode 1 structure "supported ifrom rsaid header including a -"p1anareniitting por tionisand axmarginal :portion, a ucontrol zgrifl --supportetir ifrom ;1 said header: and overlyin'g lthe remittingportionrof-said cathode, and 'an enlvelope joined tot-said i'header and" including a tern'iinal e member ihaving #an' inwardly extendingi.plainar -.porti'on ipos'itioned Jim opposed relation with'irespectitoi themarginal portions' of said cathofde i -header, an annular 'c'athode ;structurewsupported -anaenvelo'pe joined to :said Iheader and including a terminal member having "an iinwardlyzzextendin grplanar portion ip os'itione-d l in' oppo'sed; spaced arelation:with ':respect it 0- sure imarginal mortions 16f saidicathode structure,fiand antadditionalrcon- "trol :me'mber h-avingfi a portio thereofva-received ibetween rthe ropp'osed \porlti'onsrrof? said bath-ode structure and vsaid:terminal memberr '7. An electric discharge device comprising an envelope, an anode supported from one end of said envelope, an annular cathode supported from the other end of said envelope, a control member interposed between said anode and said cathode and a support for said control member positioned within and supported in insulated relation with respect to the support for said cathode, a planar member surrounding said cathode and connected therewith with respect to high frequency currents, and a terminal member forming part of the wall of said envelope and including a portion extending within said envelope in opposed relation to the planar portion and said cathode structure.

8. An electric discharge device comprising an envelope, an anode supported from one end of said envelope, a, control member supported from the other end of said envelope, an annular cathode positioned on the side of said control member remote from said anode and surrounding the support for said control electrode, a metal cylinder forming a side wall of said envelope and having an inwardly directed flange at one end therefor, said cathode structure including 2. marginal planar portion extending in opposed relation to said inwardly directed flange, and a second electrode interposed between the marginal portion of said cathode structure and said flange and capacitively coupled therewith.

and having an inwardly directed portion extendlng within said envelope, said cathode structure including a marginal planar portion extending in opposed relation to said inwardly directed portion, and a second electrodeinterposed bea tween the marginal portion of said cathode structure and said inwardly directed portion and capacitively coupled therewith.

10. An electric discharge device comprising an envelope, an anode and an. annular cathode of- U shaped cross-section, a control electrode interposed between said anode and said cathode,

ginal portion connected with said terminalmemher with respect to high frequency currents, a

hollow conductor connected with said cathode around said aperture and extending through said envelope in a direction substantially perpendicular to said marginal portion, and a plurality of direct current terminals sealed through said envelope in the region between said terminal memher and saidhollow conductor.

-- 12. Anelectric discharge device comprising an envelope, 8. terminal member sealed through said envelope; an apertured cathode having a generallyplanar emittingportion and a marginal portion lying in substantially the same plane as-said emitting portion, a screen grid including a mar- .member being joined to said control- 'ginal portionpositioned between said terminal member and the marginal-portion of said cathode and insulated therefrom withnrespect to direct current voltages and capacitively coupled therewith with. respect to high frequency currents, a control grid interposed between the emitting portion of said cathode and said screen grid, and a conductorconnected with said gridand extending through said aperture.

13. An electric discharge'device comprising an envelope, an anode supported from'one end of said envelope and having a planar active surface presented to the interior of said, envelope, a hollow cylindrical conductor sealed through the-opposite end of said envelopeand extending into said envelope a substantial distance in the directionv of said anode, an annular cathode supported from the upper end; of said cylinder, 'control member interposed between said cathode and the active surface of said anode and an elongated conductor supported Within said conducting cylinder and hermetically sealedthereto, said memberand providing a support therefor.

JAMES E. BEGGS;

REFERENCES CITED The following'references are of recordinthe

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