US3200283A - Ruggedized cathode mount - Google Patents

Description

Aug. 0, 1965 R. E. MANFRED! ETAL 3;2o0,2s3

RUGGEDIZED GATHODE MOUNT Filed May 26, 1961 FIG.2.

FIG.I.

FIG.3.

INVENTORS: ROBERT E. MANFREDI,

PAUL KOSKOS. .fgHN w. AMMENHEUSER BY THEI ATTORNEY.

United States Patent O 320283 RUG\GEDIZED CATHOIDE MOUNT Robert E. Manfredi, Rolling Hills, Calif., Paul Koskos, Maplewoad, NJ., and J hn W. Ammenheuser, Elsmere, N.Y. assgners m General Electric Company, a corporai0n 0i New York Filledl May 26, 1961, 'Ser. N0. 112,992 13 Clairns. (CH. 313-269) The present invention relates to electric discharge devices and pertains more particularly to an improved electric discharge device including improved electrode mounting means.

The prirnary object cf the present invention is to provide in an electric discharge device improved electrode mounting n1eans whereby the device is adapted for withstanding substantial mechanical shock and vibration.

Another object of the present invention is to provide an improved planar electrode beam power device including improved cathode mounting means adapted for minimizing any tendency toward thermally-caused axial displacement of an ernissive surface of the cathocie and resultant 1mdesired variations in interelectrode spacing.

Another object of the present invention is to provide an improved cathode assembly which, in addition to satisfying the above-stated objects, is particularly elfective in Ehe usage of electromagnetic waves in the input section of UHF tubes of planar electrode construction.

Another object of the present invention is to provide an improved planar electrode device including improvecl electrode mounting means efl'ective for facilitating manufacture.

Further objects and advantages of the invention Will become apparent as the following description proceeds and the features of novelty which characterize the invention Will be pointed out With particularity in the clairns annexed 110 and forming a part of this specification.

In carrying out the objects cf the invention, there is provided an electric discharge device comprising an envelope structure including a stacked series cf axiallyaligned cerarnic insulators. Mounted in one end 0f the envelope is an anode electrode. Sealed between the opposed ends of adjacent insulators are a plurality of axially spaced annular metallic contact rnembers With inner rim portions disposed internally of the envelope. The inner rim of one of the contact rnembers serves as a reference surface adapted for being engaged by a grid assernbly for thereby providing a predeterrnined spacing between the anode and grid assembly. Supported by and electrically connected to the inner rirn of each of an adjacent pair of the contact members is a coaxial generally cylindrical resilient combined contact and detent ele1nent forrned With multiple outwardly bent spring finger contacts. A grid assembly is adapted for being held in position against the mentionecl reference surface by a detenting efr"ect of the bent spring fingers o1": one 0f tl1e resilient contact elements. The spring fingers also provide an annular electrical C011- nection between the grid assembly and one of the annular contact mernbers sealed in the envelope wall. Bearing against the gn'd assembly is a cathode assembly including a conductive cathode support member having an onter cylindrical rim portion. Engaging the rirn portion of the cathode support member with a detenting effect are the bent spring fingers of the other resilient contact. A contact mernber axially spaced from the above-mentioned adjacent pair of contact rnembers rernovably supports a retainer cup which carries a cornpressed coil spring which assists in biasing 1.he cathode assembly against the grid assernbly for maintaining these assemblies in desired stacked relation. The cathode assernbly comprises an insulative cylinder which eifects the bearing relation with the grid assembly. Additionally, the cathode assernbly cornprises a conductive support sleeve coaxially supported in and by the insulative cylinder. Concentrically located in the support sleeve in radially spaced relation thereto is a cup-shaped emitter. Provided between the sides of the emitter and conductive support sleeve are a pair of axially spaced annular straps. The straps eacl1 include circumferentially spaced indented and protruding sections which are alternately arranged and, respectively, are secured to the sides of the emitter and support sleeve. Additionally, the indented sections of one strap are vertisally aligned with the protruding sections of the other strap and the protruding sections cf the one strap are vertically aligned with the indented sections of the other strap. The straps provide a rugged mount for the emitter, avoid thermally caused axial displacement and serve in providing a high frequency capacitive action between the ernitter and support sleeve juncture.

For a better understanding of the invention reference may be had t0 the accornpanying drawing in which:

FIGURE 1 is an enlarged partially sectionalized view of an electric discharge device incorporating an embodiment of the invention;

FIGURE 2 is an enlarged plan view of the cathode assembly; and

FIGURE 3 is an enlarged fragmentary perspective view of the cathode assembly.

Referring to the drawing, there is shown in FIGURE 1 an electric discharge device embodying a forrn of the present invention and including an envelope structure generally designated l. The envelope structure illustrated comprises a first cylindrical ceramic insulator or section 2 which Supports an anode assembly generally designated 3. The anode assembly comprises an anode block 4 having an inner and sealed in and closing one end of the envelope and including a radiator structure on the external end thereof. Additionally, the inner end of the block 4 includes a planar active surface 5 located in the envelope. The envelope further cornprises a vertically stacked coaxially aligned series of cylindrical cerarnic insulators or sections including three other ceramic cylinders of the Same diameter as the cylinder 2. For convenience of reference, these last-mentioned three cylinders are designated 6, 7 and 8.

Hermetically butt-sealed between the opposed ends of insulators 2 and 6 is a generally cup-like screen grid contact 10. Similarly sealed between the opposed ends of insulators 6 and 7 is a similar control grid contact 12 having an outer diameter larger than that of the screen grid contact 10. And sirnilarly sealed between the opposed ends of insulator 7 and 8 is an annular cathode contact rnember 13 having an outer diameter larger than that of the control grid contact 12.

The lower and of the envelope 1 is hermetically closed by a header construction comprising cylindrical insulators and annular contact mernbers associated with a cathode heater. This portion of the envelope comprises no part of the present invention and, therefore, need not be described further.

The screen grid contact 10 includes an inner rirn portion 14, which includes an under surface adapted for serving as a reference surface, or electrode positioning stop, predeterrninedly spaced frorn the active anode surface 5. Provided for bearing against the under surface of the rim 14 is a grid assexnbly generally designated 15. The grid assembly 15 can be identical to that described and claimed in copending application Serial N0. 832,994 filed August 6, 1959, now Patent Number 3082339 of R. E. Manfredi entitled, Electric Discharge Device, and assigned to the sarne assignee as the present invention.

As illustrated and described in detail in the aforesaid copending application of R. E. Manfredi, tne grid assembly 15 includes a planar screen grid 16 and a planar control grid 1'7. Each of the grids 16 and 17 comprises a substantially thin conductive washer including a straight diametrically extending cross-bar across which are brazed a plurality of closely spaced parallel co-planar grid wires 18. Additionally, the grids 16 and 17 are separatecl and mutually insulated by an insulative washer 19 interposed therebetween. The grids are suitably bonded to the opposed sides of the insulative washer and, thus, a unitary gi'id assembly is provided.

Electrical connection t the screen grid 16 is provided through the contact and its inner rim 14. Electrical connection between the contact 12 and the control grid 17 is provided by a multiple spring finger cylindrical contact member 20. The lower end of the mernber 29 is fitted over and is suitably conductively secured to a cylindrical rim 12 formed on the contact member 12 internally of the envelope. The cylindrical member 20 is formed of any suitable resilient material adapted for satisfactory radio frequency conduction and includes multiple individual spring fingers, as shown. Additionally, the ends of the spring fingers are outwardly bent to serve additionally as detenting or retaining elements.

The ends of the spring fingers bear against an edge of a cup-like annular conductive member 21 which fits about and makes electrical contact With the control 17. Thus, an annular radio frequency connection is provided between the contact 12 and the grid 17 as Well as centripetal and axial forces tending to hold the grid assembly centrally in platte against the reference surface.

Bearing against the underside of the member 21 is a cathode assembly generally designated 22. The cathode assembly 22 includes an insulative cylinder 23 which can advantageously be formed of ceramic, a generally cylindrical cathode support sleeve 24 including an upwardly extending inner cylindrical section 25 and a dependent outer cylindrical section 26 of greater diameter. The sleeve sections 25 and 26 are separated by a radially extending stepped portion 27 and, as seen in FIGURE l,

the stepped portion 27 is sandwiched and bonded between the ceramic cylinder 23 and a back-up ceramic washer 28.

Positioned concentrically in the support sleeve section 25 is an emitter structure including a cup-shaped momber 36 having a planar active surface 31 and a cylindrical skirt 32. The emitter contains a heater arrangement comprising a helically coiled filament 33 arranged in a flat spiral and sandwiched between a pair of approiariately grooved ceramic washers 34. The ends of the filament extend from the coiled portion through the centers of the ceramic washers and are connected to heater leads 35 which extend downwardly and are appropriately electrically connected to heater contacts provided at the lower end of the tobe envelope. An end plate 36 is provided for holding the heater structure in the cathode cup. Additionally, the end plate 36 carries a dependent sleeve upon which is supported a cylindrical getter element 37.

As perhaps better seen in FIGURES 2 and 3, the cathode cup 30 is bald in the support sleeve 25 by means of a pair of axially spaced annular conductive support straps 40. The straps 40 are each formed to include a diametrically opposed pair of bail-like indented, or inwardly extending, sections 41 and a pair of bail-like protruding sections, o1 outwardly extending sections, 42 spaced 90 apart from the indented seCti0ns 41. Additionally, the upper strap is rotated 90 relative to the lower strap so as to place each indented section in the upper strap in corresponding or vertical alignment With the protruding section in the lower strap and each indented section of the lower strap in corresponding or vertical alignment With a protruding section in the upper strap, in the manner shown in FIGURE 2. Additionally, the indented sections 41 of both straps are spot welded to the skirt 32 of the cathode cup and the protruding sections 42 are similarly secured to the inner surface of the support sleeve section 25. Thus, the cathode cup is rigidly mounted at a plurality of circumferentially and axially spaced points thereabouts, whereby it is adapted for withstanding substantial mechanical shock and vibration without breakage 0r alteration of the interelectrode spacing between the active surface 31 of the cathode and control grid.

Further, the st1aps 40 are shaped so that the sections thereof interconnecting the indented and protruding sections, and designated 43, are substantially long and are located generally rnidway between the Walls of the cath- Ode skirt 32 and support sleeve section 25 and in spaced relation to these elements. In this anangement the sections 43 comprise substantially long and relatively narrow thermal paths, With the desirable results of improved cathode thermal efiiciency and minimal heat transfer to the support section 25. The improved thermal etliciency minimizes the power requirements for the heater. Also, the minimal heat transfer to the section 25 from the cathode minimizes any tendency for that setcion to expand thermally longitudinally or axially and, therefore, serves substantially to avoid, or to minimize, therrnally-caused axial displacement of the cathode and resultant undesired variations of the interelectrode spacing. Thus, the active surface 31 of the cathode undergoes minimal, if any, axial displacement between the heated and unheated states thereof which serves to avoid objectionable radio frequency drifts or variations during early operation of the tobe when substantial temperature variations ordinarily occur. Additionally, the individual straps can expand thermally length-wise without aifecting the position of the cathode.

The strap sections 43 serve also to provide a desired jradio frequency by-passing action between the cathode cup 30 and the support sleeve 22. Specifically, the strap sections 43 represent substantial conductive areas between the cathode cup and support sleeve and, thus, provide for a radial high capacitance between the latter two elements. This increased capacitance effectivelY shorts out or counteracts any inductance of the strap Witl1 the desirable result that the region between the cathode cup and support sleeve appear as an electrical short to radio frequency currents in a resonant circuit including the cathode. Thus, the cathode mount structure provides desired radio frequency continuity to the active face of the cathode, or, in other words, constitutes a configuration particularly well adapted for the transfer of electromagnetic waves up to, and the unimpeded interaction of such electromagnetic waves With, the electron beam between the planar electrodes.

For some applications the straps 40 can be generally oval er rectangular with the emitter secured between the longer sides and the protruding end sections to the support sleeve. In (bis arrangement the protruding end sections of one strap can be rotatively displaced relalive to the corresponding sections on the other strap f0r improving the rigidity of the structure.

Provided for electrically connecting the cathode assembly and the cathode contact 13 is a cylindrical multispring finger contact member 45 which, as seen in FIG- URE l, is suitably supported on an immer cylindrical section 46 of the cathode contact member 13. The cylinder 45 can be generally similar to the spring finger cylinder 20 cooperating with the grid assembly and also includes multiple outwardly bent spring fingers. The spring fingers contact the outer edge of the support sleeve section 26 and provide a suitable radio frequency comnection between the cathode and cathode contact as weil as centripetal and axial forces tending to hold the cathode assembly in place against the grid assembly.

The cathode assembly is also hold in the position shown in FIGURE 1, in which it bears on the gricl assernbly 15, by a relatively large coil spring 47, the upper end of which spring bears against the outer rim of a cup-like shield element 43 between the spring and the cnthode assembly directly beneath the back-up washer 28. The lower end of the spring 47 is seated in a retaining cup 49, the center of which is apertured for extension therethrough cf the filarnent leads 35. Provided for removably holding the retaining cup 49 in position are two pairs of detents 50 and 51, each bent out of the side Wall of the retaining cup 49 and the inner cylindrical section 46 of the cathode contact 30, respectively. The

construction including the coil spring, the retaining cup and detent arrangement does not constitute part of the present invention but is disclosed and clairned in the above-identified co-pending application of R. E. Manfredi.

In manufacture, the device envelope is first fabricated including all of the above-described insulative sections, the electrode contacts, spring finger cylinders on the inner rirns of the screen grid and control grid contact members, and the anode assembly, or in other words, all of the disclosed structure except the grid and cathode subassemblies and the lower end header -construction.

The above-described grid and cathode assemblies are separately fabricated and in assembling these structures in the device the grid assembly is pushed upward until the upper surface cf the control grid engages the screen grid contact inner rim 14. At this point the bent spring fingers on the control grid multiple spring finger contact cylinder snap under the member 21 instead of detents to hold the grid assernbly concentrically positioned and against the rim portion. During subsequent operation of the tube the spring finger contacts also serve in providing an annular highly effective radio frequency current path to the control grid. Following the described insertion of the grid assembly the cathode assembly is in serted into the position illustrated in FIGURE 1 and the spring fingers 0n the multiple spring finger contacts cylinder 45 snap into the illustrated position between the edge of the cathode support sleeve section 26 and serve to hold the cathode assernbly in a concentric assembled osition. During operation of the tube the spring fingers of the cylinder 45 serve also to pxovide an annular effective radio frequency current path to the cathode assembly. Following insertion of the cathode assembly the shield rnember 48, spring 47 and retaining cup 49 are positioned in the device and the spring 47 is compressed by exertion 0f an inwardly directed force on the retaining cup, following which the retaining cup is rotated into a locked position. In this manner, the grid and cathode assemblies are rigidly held in predeterminedly spaced relation in the device. Subsequently, the filarnent leads are suitably connected to filarnent contacts in the lower end header construction, that construction is sealed in place and the device is evacuated in the usual manner.

While there -is shown and described a specific ernbodiment of the present invention, it is not desired that the invention be limited to the particular form shown and described, and it is intended by the appended claims to cover all modifications within the spirit and scope of the invention.

What is clairned as new and desired to be secured by Letters Patent of tne United States is:

1. A cathode assembly comprising a conductive support sleeve, an emitter coaxially disposed in said sleeve and radially spaced therefrorn, at least one conductive strap surrounding said emitter and interpositioned between said emitter and said sleeve, said strap including diametrically opposed protruding sections secured only to said sleeve and sections intermediate said protruding sections secured only to said emitten 2. A cathode assembly according to claim l, wherein a plurality of axially spaced straps are employed and the protruding sections of one strap are rotatively displaced relative to the protruding sections of another strap.

3. A cathode assembly comprising a conductive support sleeve, an emitter coaxially disposed in said sleeve and radially spaced therefrom, conductive rneans supporting said emitter in said sleeve comprising a first pair of diametrically opposed protrusions extending from said ernitter and secured only to said sleeve, a second pair of diametrically opposed protrusions axially spaced from said first pair and extending from said emitter and secured only to said sleeve and the protrusions of said first pair being rotatively displaced relative to the protrusions of said second pair.

4. A cathode assembly cornprising a conductive support sleeve, an emitter coaxially disposed in said sleeve and radially spaced therefrom at least one annular Conductive strap interpositioned between said sleeve and emitter, the major portion of which is spaced from both said sleeve and said emitter, said strap having alternate circurnferentially spaced indented and protruding sections secured, respectively, to said emitter and support sleeve.

5. A cathode assernbly according to claim 4, wherein said strap is of rectangular cross-section With the greater dimension co-extensive With the axes of said emitter and sleeve, and the sections 0f said strap intermediate said indented and protruding sections are radiallly spaced relative to both said emitter and support sleeve.

6. A cathode assembly according to claim 4, wherein said indented and protruding sections are spaced apart.

7. A cathode assembly comprising a conductive support sleeve, an emitter coaxially disposed in said sleeve and radially spaced therefrorn, a pair of axially spaced annular conductive straps interposed between said sleeve and emitter, said straps having alternate indented and pro truding sections spaced 90 apart and secured only, respectively, to said emitter and support sleeve.

8. A cathode assernbly according to claim 7 wherein the straps are rotatively oriented such that the indented and protruding sections of one strap are displaced 90 relative to corresponding sections of the other strap.

9. A cathode assernbly according to claim 1, wherein said ernitter has a planar active surface, said support sleeve includes a radially extending section to the upper surface of Which is bonded an insulative sleeve, and said insulative sleeve has an end surface protruding beyond the active surface of said emitter, a predeterrnined amount and constituting a reference surface for locating another electrode in predetermined space relation to said active surface of said emitter.

10. A cathode assernbly comprising a conductive sup port sleeve, including a pair of tubular sections of difierent diameters interconnected by a generally planar radially extending section, an emitter coaxially disposed in the smaller of said sections and radially spaced therefrurn, at least one coaxial annular conductive strap interposed between said ermitter and said srnaller section, said strap having circumferentially spaced protruding sections and intermediate sections secured only, respectively, to said smaller tubular section and emitter, an insulative sleeve bonded to one surface of said radially extending section of said support sleeve and protruding a predetermined amount beyond said ernitter, said insulative sleeve being effective for serving as a reference element to locate another electrode in predetermined spaced relation to said emitter, and the larger section of said support sleeve coustituting an annular contact surface for said assernbly.

11. A cathode assernbly cornprising a conductive support sleeve, an emitter coaxially disposed in said sleeve and radially spaced therefrorn, a coaxial pair of axially spaced conductive straps interposed between said support sleeve, an emitter, said straps having alternate circumferentially spaced indented and protruding sections secured only, respectively, to said emitter and support sleeve.

12. A cathode assernbly according to claim 11, wherein said straps are rotatively oriented such that the indented and protruding sections in one strap are aligned with alternate indented and protruding sections of the other strap.

13. A cathode assembly according to claim E1, wherein the indented and protruding sections of each strap are '5 8 spaced 90 apart and the straps are rotative1y oriented 2,907911 10/59 Miller 313-252 such that the indented and protruding sections of one 3128407 4/64 Mattson 3'13270X strap are displaced 90 relative to corresponding sections FOREIGN PATENTS 0f the other strap.

5 1,234,618 10/60 France.

OTHER REFERENCES Doner, Electron Discharge Device Structure, RCA TN References Cited by the Examina:

UNITED STATES PATENTS 2810088 10/57 MacNair 313339 N0. 449, January 1961 (page 2 relied upon). 2,810090 10/57 MacNair 313-339 2,8 13,219 11/57 Hanft et a1 3 1325 2 10 EORGE N. WESTBY, Primary Examiner.

2905742 9/59 W0ods 313-312 X RALPH G. NILSON, Examina.

Claims (1)

1. A CATHODE ASSEMBLY COMPRISING A CONDUCTIVE SUPPORT SLEEVE, AN EMITTER COAXIALLY DISPOSED IN SAID SLEEVE AND RADIALLY SPACED THEREFROM, AT LEAST ONE CONDUCTIVE STRAP SURROUNDING SAID EMITTER AND INTERPOSITIONED BETWEEN SAID EMITTER AND SAID SLEEVE, SAID STRAP INCLUDING DIAMETRICALLY OPPOSED PROTRUDING SECTIONS SECURED ONLY TO SAID SLEEVE AND SECTIONS INTERMEDIATE SAID PROTRUDING SECTIONS SECURED ONLY TO SAID EMITTER.

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