US2808527A

US2808527A - Cathode support strap

Info

Publication number: US2808527A
Application number: US548367A
Authority: US
Inventors: Robert T Mckenzie
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1955-11-22
Filing date: 1955-11-22
Publication date: 1957-10-01
Anticipated expiration: 1974-10-01
Also published as: GB831426A

Description

Oct. 1, 1957 R. T. MCKENZIE 2,808,527

CATHODE SUPPORT STRAP Fi led Nov. 22, 1955 Un te S tes Fatcfir 23 5 1 CATHODE'SUPNDRT'STRAPT' Robeeer -MKeiizie; Polo Angelina, assig'n'ot' tofl General Electric Company, a corporation L New-York V Applie'ationNovembef 22,1955; Serial N6. 548,3 67 17 Claims.- {01.313 82}:

Mylinv'ention relates to cathode-ray tubes andlmore particulafly' to supportstr'aps forcathodsemployedin the electron gun r -Hretofore;-in beenfsupportd within a whiclfis in"turn attached bystraps-to tlie'insulative'rods. which are disposed in spaced relation -to support the-array) ofele'ctrode' elements: in predetermined alignment; The cap-pedend of the thimble-shaped grid has. a centrallyidisposed aperfur'e which permits passage o-f tlie@ electron beani. Th*e' cathod isg'enerally of the indiIectIyHheated type and consists ofa cylindrical sleeve 'havingia disk} usually madeiroma nickelalloy. andcoated.witli.=an. electron emisTsive-materialj cappingeone end of -thetsleeve The cathode is 'in'serted sueh that the coated disk'ts'. dis posed adiacentf to andhiaintained a predetermined idistzinCeffGrhWhaperturby' an accurately. stamped and. sizede aeedwhion fitsfbetwe'enthe cappedend of the? rid assembly and the insulative disk afiiired to the cath; ode. An insulati-ve circulaf coll'air-is afiiked to the-cathode" andositions: the-cathode within-the grid 'such'f that the cathodefis' a axially"aligned' with said aperture. The? spaced-and the cathode including the "collar are retainedin position by spofwelding an expanding split ringzwithin the controrf g'rid' which?" bears against the underside of. the cathode disk and maintains the cathode snuggly. against the: spacer.; In" assembly, the: .aforementioned' spacer 'isiinitially -fitted within the -control grid assembly, the cathodeiandtheafliXedinsulativedisk'are then in-.. serted-sndl1 thatth'e disk bears against "the spacer, and finally the expanding split ring is inserted and snug-ged against "the'fj kstamped'andsi'zed spacer, a ceramic disk, and Tan expandi'ng splifring m'ust'b inserted, and"a'sp-otf weld-l mgoperation must {be perfiormed,resultinglin a series of steps Whichare timeconsumingand costly. Another disadvantage or-the rior art cathode-structure is 'jthat of tlie cathbd fiifs for 1 any reason, the entire electron gun assembly and even the entire tube may have'to be re'pltced?- i 1 Accordingly; it-is a 'principal -object"ofmyrinvention to rovide a 'new ianuimproved oatho'desupport-tor an' electron gun" assembly that exp editiously" and eflicienfly affiXes"tlie --ca'thodein redetermined relation to the'other elctio'de' el mentsik Another object ofiniy inve'ntion -isto rovide =a new: anclimproved cathode support strap for a cathodef-ray tube 'th'ae permits individual 1 replacement of the==catliode element.

Another object of-=myinvention-is to provide al -new and improved cathode support that permits eorrect-ly positioning the cathodeduring the one" operation that includes anchoring the other' electrode element's to tlie supportro'ds;

Further objects and I a d-vantages 'ofmy invention will beeomeiapparent fiom the following de'scription'; an'l fthe features of -novelty whicli characterizemy invntiorfiwill assemblies of cathode ray tubes.

electron gunassemblies, the cathode has t-thim'ble-shaped control: grid ppositei side of "the collar and spot "welded.

be pointed out'with particularity insthe claims annexedl toand forming part or this specification, I

Incarr ing out the objects of mywinvention I provide novel cathode suppblfs' reruse in electron 'gunstructures,

said cathode. supports-comprising strap means anchoring directly"? tothe in'sulative: rod; members which] maintain-i the other electrode elementsrin spaced relation.

Fora detailed explanation of my invention, reference isifiadto fthe' acconipanyingfldrawings in which-z I Figure -l is an elevation section view of 'a cathode ray tube"gun"structur embodyingsfeatur'es of'th'e presentinvention:

Figure '1 2 is .ai fragmentary enlarged elevation view, partly,'injfcrossfsection; ,vofthe cathode-control grid portiomofFi'gure 'lj ofFigure 2;

Figure" 4" is?" a fragmentary enlarged elevation view; partlylificross' section;' of the cathodecontrol grid por tionofFigure 1 1 showing a modified embodiment of the invention;

Figured-"is ail-"exploded isometric-view of Figure -5 figure 7"is' 'a'nelevationvievv, partly in cross section, of th'e"cathode structure of Figures 1; 2" and 3? andincluding'the jigused'inassembly;

Figure'8 isf-an"elevationView; partly in cross section, of the modifiedkmbodimentof the inventionof Figures Figure=9"is' anenlrged (elevation view; partly in cross section; oFStiIIanother embodimentofthe invention;-

Fi ure-101s" anis ometricview of theistrap oi Figure 9.

In Figure 1", anfelectron "gunis shown located in the neck portion 11 ofa" cathode ray;- tube envelope; saidgun includingta"controfgrid electrode'l2, a number two orscreen'grid' 13, an anode 14, and "a magnetic focusing, meansgenerally indicated at: 151 Eachl of the preceding elementsiorassemblies may -be' of any suitable conven-. tional" design, and"'forpurp oses well known; to those skilled in the art. Lead" wires" connecting j the r elements 1'3, and" 14 to' the closed-end of the neck portion 11 alenot shown since:thei-arrangements" therefore and them'annerof .c'onne'ctioirare well known toithose skilled in-tb-art; and, .per se, form no'parf of my invention. Spacerf clips 16 fof 5 any "suitable: conventional type can befused to maintain the -gun"assembly"in proper spaced relation to'the wall oftheneck portion 11; as is also wellknown' inthe art.

.Whilenthe; present" inventiomwill lie'described in asso ciatiom-with' 'a--m-agnetic" focus type. of gun structure, it will be understood that it is notli mited to this '-particu-' lar type of gun; it beingwl-e'ar that electrode elements similar to those illustrated at'12j13j1and'14,"or'the equiva: lent; .are commonly 'ernployed in electrostatic focused guns of th 1 so called -bentgun, tilted-straigh't-gun; and other types.

For maintaining? the

electrodeelements

12, 13; and! 14; int:.spacedwalignment; (one 01 more insulat'ive glass" rods on-bea'ds e17, i18 -a-re provided:imparallel spacedi re lation to-said elements-.andqhe control-grid 12, thescreen: grid 13, and theanode14:-.a-reconnected to the glass? "beads17, 18 by meansof support or beading strapsl'l, 22; 23 and 24 respectively. In accordance with a feature of the invention-andas illustrated more clearly in Figure 2; the cathode structure 29 is positioned within the control'g'rid 12"and' is 'afiiiied' to the support" bead '17. by support strap"3 7.'

Figure 2 shows the cathode structure 29*assembled', while Figure 3? shows" a' pietorial 'view' of the cathode structure29 sepa-ratelyz Thecathode consists ofan in direetly heated cylindrical sleevei26 having a -disk Patented Oct. 1,195.7"

Fgu'rea isl'a'n'is0nitric view of the cathode structure? 3 which may be integral with said sleeve, capping one end of the sleeve, and a thin electron emissive material coating 28 on the disk 27. An insulative collar 31, preferably a ceramic, is friction fitted around the periphery of the sleeve 26. Protrusions 32 are formed on the sleeve 26 adjacent the upperand lower surfaces of the collar 31 after the collar is placed in position and serve-to maintain the collar 31 in predetermined position on sleeve 26;

A shoulder 33 is formed on the periphery of the collar 31 to permit the separated strips of body portions 34 of the strap 37 to engage the shoulder 33 therebetween and thus to securely grip the collar 31. Arms 35 of the strap 37 fold back onto themselves and may be affixed to each other as by spot welding. Spaced terminal portions 36 ,of the strap 37 are adapted to be embedded in the

beads

17 or 18 and are, therefore, formed with recesses to permit molted bead material to be received therewithin; this type of configuration provides increased stability of support. The terminal portions 36 are further formed in parallel bifurcated relation in order to achieve a double grip effect when the terminal portion 36 is inserted into the glass bead 17. It has been found that the double grip herein disclosed provides a secure hold, rigidly aifixing the strap 37 to the bead 17.

During assembly in the electron gun, the cathode structure 29 is maintained in a predetermined position within the grid 12 by means of an aligning tool or jig 38 shown in Figure 7. Jig 38 has a center projecting pin 41 which is adjusted in length by locking screw 42. Sleeve 26 is initially fitted over projecting pin 41 and then the jig 38 and the cathode structure 29 are inserted into the control grid 12, thus locating the cathode 29 centrally and also a predetermined distance from the capped end of control grid 12. The electron beam controlling elements are all placed in a machine jig which maintains the elements in correct position. Cradles (not shown) are adapted to hold the

glass beads

17 and 18 are disposed in spaced relation beneath the straps. After a bead of glass is melted in the cradle the machine jig is actuated such that an end of each of

thestraps

21, 22, 23 and 24 which are affixed to each of the respective electrode elements is inserted into the molten bead 17. The terminal portions 36 of the cathode strap 37 are inserted into one of the beads, say bead 17, conjointly with one end of the

straps

21, 22, 23 and 24. After the

straps

21, 22, 23, 24 and 37 are inserted, the bead 17 is allowed to cool. The molten material which has distributed itself around the respective terminal portions 31 of the

straps

21, 22, 23, 24 and 37 securely anchors the straps to the bead rod. The gun structure unit is next withdrawn leaving the cathode structure 29 securely positioned in predetermined relation with the control grid 12 and ready for further assembling of the electron gun in the cathode ray tube.

The capped cylinder comprising the control grid 12 is preferably designated somewhat less deep than previous grid cylinders to permit the use of a short strap; a short strap will provide a more stable support. 1

Figure 4 shows a modified embodiment of my invention. Previously if a cathode became defective the entire electron gun structure had to be removed and replaced or else the entire tube was scrapped. For many applications it is desirable to be able to replace only the cathode without disturbing the rest of the electron gun assembly. In accordance with the invention, an easily replaceable cathode is provided that will have all the characteristics of a permanent cathode. In this embodiment of my invention, the sleeve 26 is smooth; having no embossments the sleeve can be slidably fitted through the collar, as can be seen clearly from Figure 6. The strap 37 is fitted to the collar 31 in the same manner as in the first embodiment. A tie strap 43 is designed to have arm a 2,808,527 i i a M struction having the body portion wrapped around and afiixed to sleeve 26.

During assembly, the entire cathode structure 29 is positioned by jig 38 in the same manner as in the first embodiment. Tie strap 43 is initially spot welded to support strap 37 and then the entire cathode structure 29 is positioned within grid 12 by jig 38, Figure 8. Terminal portions 36 are next imbedded into bead 17 to secure the cathode structure 29 in position; the jig 38 is then withdrawn and the unit is ready to be assembled in the tube.

Should the electron emissive surface 28, or any part of the cathode sleeve 26 become defective the entire sleeve 26 can be removed by simply cutting arms 45 of tie strap 43 and pulling sleeve 26 out. Replacement of sleeve 26 can be effected by placing a similar sleeve, to which a replacement tie strap 43 had preliminarily been suitably aflixed, onto the projecting pin 41 of the jig 38 and inserting the jig 38 in the grid 12. Pin 41 in jig 38 will position the sleeve and associated strap at a predetermined distance from grid 12, and the already centrally positioned ceramic collar 31 will maintain the sleeve in axial alignment. Next, the free ends of the arms 45 are spot welded or otherwise secured to the arms 35 of the support strap 37 and jig 38 is withdrawn and the sleeve 26 is ready for further assembly.

' Yet another embodiment of my invention is shown in Figure 9 in which the cathode structure 29 is anchored to two

support rod members

17 and 18. In this embodiment, support strap 46 is formed of two similar pieces each having centrally disposed semi-cylindrical center portions 47, and radially extending arm portions 48, the latter being disposed in substantial registry and placed back to back, Figure 10. The two semi-cylindrical center portions 47 are affixed to form a pair of vertically spaced encircling bands, securely gripping the collar 31 atop and below the shoulder 33, Figure 9.

A jig similar to jig 38 but having an additional cutway portion to provide for the diametrically opposed strap extensions is employed to assemble the cathode structure. The embedding process is also similar except that the extensions 48 of the strap 46 are inserted into both

rods

17 and 18. This embodiment is useful where an even more rugged support for the cathode is desired. A replaceable cathode sleeve of the type shown in Figures 5 and 6 can also be employed in this embodiment; tie straps 43 would then lead from the cathode sleeve 26 to either or both extensions 48.

It will be understood that While the straps described hereinabove were wrapped around or encircle the units other means of aflixing the straps to the collar such as by crimping, by prongs, or by welding may be employed.

Further, it will be understood that said straps may also be formed integrally with the cathode sleeve as for example by striking out portions of the sleeve wall to form the extending portions.

It will further be understood that while glass beads or rods were described 'hereinabove, rods of other insulaportions 45 positioned astride arms 35 of support strap 37, as shown in Figure 5. For practical manufacturing considerations the strap 43 is about single piece contive material can be similarly employed such as quartz, mica, ceramic or the like as a base for anchoring the electrode elements of the gun assembly. Also, it will be understood that while a plurality of glass rods were described, a single rod may be employed as the supporting member.

Although the present invention has been illustrated by specific examples, it will be obvious to those skilled in the art that modifications may be made without departing from the spirit thereof.

, 'What I claim as new and desire to secure by Letters Patent of the United States is:

' 1. In an electron gun assembly, an insulative rod member, 'a plurality of electrode elements supported in spaced alignment by said insulative rod member, a single arm anchored at one end in said rod member, and a sleeve shaped cathode element supported exclusively by said arm independently of others of said electrode elements.

2. In an electron gun structure having at least one insulative rod member and a" plurality of electrode elements adapted to be supported in spaced alignment by said insulative redme nber', a cathode element comprising a sleeve, and means for supporting said cathode element exclusively from said rod independently of the other electrode elements comprising strap means afiixed' to said cathode and having a termination secured to said rod member.

3. In an electron gun asseninly, a plurality of electrode elements supported in spaced axial alignment by at least one insulative support member, a sheet fiietal strap having a widtli substantially greater than its thickness and having one end embedded in said support member with the lane of said strap parallel to the axis of said electrade elements, and a cathode element comprising a thimble-shaped sleeve mounted on said strap with the axis of said sleeve coincident with said axis of said electrode elements.

4. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a cathode, and a single strap connected between said rod member and said cathode exclusively supporting said cathode from said rod member independently of and in spaced relation to said other electrode elements.

5. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a cathode element comprising a tubular sleeve, aninsulative collar mounted on said sleeve, strap means including a body portion fitted on said collar, arm portions folded back onto themselves and afixed to each other, and terminal portions integral with said arm portions, said terminal portions being disposed in furcated parallel relation and adapted to be imbedded in one of said rod members.

6. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a cathode element comprising a tubular sleeve, an insulative collar mounted on said sleeve, protrusions on the periphery of said collar, strap means comprising a body portion adapted to be wrapped around said collar, said body portion having separated strips to engage said protrusions therebetween, arm portions folded back onto themselves and aifixed to each other, and terminal portions adapted to be afixed to one of said rod members, said terminal portions disposed in bifurcated parallel relation to provide a double grip on said rod member.

7. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a cathode element comprising a tubular sleeve, an insulative collar mounted on said sleeve, protrusions on the surface of said sleeve for maintaining said collar in position, protrusions on the periphery of said collar, strap means having a body portion adapted to be wrapped around said collar, said body portion having separated strips to engage said protrusions therebetween, said strap means having arm portions folded back onto themselves and afiixed to each other, and said strap means having terminal portions adapted to be afiixed to one of said rod members, said terminal portions disposed in bifurcated parallel relation to provide a double grip on said rod member.

ing portions being aflixed in back to backrelation, and said extending portioninc-luding terminal portions adapted to lie secured to said rod members, said respective terminal portions being disposed in furcated relation.

8. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by a plurality of insulative rod members, a cathode comprising a tubular sleeve, a collar mounted on said sleeve, strap means afiixed to said collar, said strap means comprising similar pieces, each piece having a semi-cylindrical center portion and extending portions, said semi-cylindrical center portions being disposed to form a peripheral band around said collar, said extend- 9 In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by a plurality of insulative rod members, a cathode comprising a tubular sleeve, a collar mounted on said sleeve, strap nieans'afiixed to said collar, said strap means comprising two similar pieces, each'piece having a center portionadapted to be 'afiixed to said collar, extension portions'being" alfixed in back toback relation, and terminal portions being disposed in furcated relation and adapted tobe secured to said rod members.

10. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment byaplurality'of insulative rod members, a cathode of the indirectly heated type comprising a tubular sleeve, a collar'nrounted on said sleeve, strap. means includin center portions and extending portions, said center portions affixed to form peripheral bands around said collar, said extending portions including terminal portions adapted to be secured to said rod members, said extending portions being affixed in backto back relation, and said terminal portions being disposed in furcated relation with respect to each other.

11. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a cathode element comprising a tubular sleeve, an insulative collar slidably fitted on said sleeve, a first strap means attached to said collar, said first strap means having terminal portions adapted to be anchored to said rod members, and a second strap means afilxed to said sleeve and to said first strap means.

12. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a cathode element comprising a tubular sleeve, an insulative collar slidably mounted on said sleeve, having a body portion aflixed to said collar and having arm portions afiixed to each other, said strap means adapted to be anchored to one of said rod members, and a second strap means having one end attached to said sleeve and having the other end attached to said first strap means.

13. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a cathode element comprising a tubular sleeve, an insulative collar slidably mounted on said sleeve, strap means having a body portion wrapped around said collar and having arm portions affixed to each other, a second strap means having a body portion being formed into a band around said sleeve and secured thereto, said second strap means having extensions positions astride said first strap means and ailixed thereto.

14. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by a plurality of insulative rod members; a cathode element comprising a tubular sleeve; an insulative collar slidably mounted on said sleeve; a first strap means affixed to said collar; said strap means having a body portion wrapped around said collar and arm portions folded back onto themselves and affixed to each other; said arm portions including terminal portions disposed in furcated relation and adapted to be imbedded in one of said rod members; said terminal portions being formed to receive flowable material of said insulative member therewith; and a second strap means having a body portion aflixed to said sleeve and arm portions affixed to said first strap means.

15. In an electron gun assembly having a plurality of electrode elements adapted to be supported in spaced alignment by at least one insulative rod member, a thimbleshaped control grid, a cathode element disposed withln said grid, said cathode element comprising a tubular sleeve,

a collar slidably mounted on said sleeve, a first strap means afiixed to said collar, said collar and said first strap means maintaining said sleeve in predetermined central alignment within said grid, said first strap means adapted to be secured to said rod members, and a second strap means afiixed to said sleeve and to said first strap means to secure said sleeve a predetermined distance from the capped end of said Thimble-shaped grid.

16. In an electron gun assembly having a plurality of electrode elements adapted to be supported in axial alignment by at least one insulative rod member, a thimbleshaped control grid, a cathode element disposed within said grid, said cathode element comprising a tubular sleeve, a collar slidably mounted on said sleeve, a first strap means for anchoring said sleeve to said support members, a collar fitted on said sleeve, said strap means afiixed to said collar to maintain said sleeve in axial alignment, a second strap means afiixed to said sleeve and to said first strap means to maintain said sleeve at a predetermined position along the axis of said grid.

s 17. A cathode support strap for an electron gun of the type having a polarity of electrodes adapted to be supported in spaced alignment by at least one insulative rod,

said strap having a cathode receiving portion, and an arm References Cited in the file of this patent UNITED STATES PATENTS Haetr' Dec. 15, 1936 r 2,153,223 Young Apr. 4, 1939 2,217,198 Davisson Oct. 8, 1940 2,429,824 Koch et a1 Oct. 28, 1947 2,573,287 Szegho Oct. 30, 1951