US2740913A

US2740913A - Electron gun

Info

Publication number: US2740913A
Application number: US254298A
Authority: US
Inventors: Charles P Majkrzak
Original assignee: Deutsche ITT Industries GmbH
Current assignee: TDK Micronas GmbH; International Telephone and Telegraph Corp
Priority date: 1951-11-01
Filing date: 1951-11-01
Publication date: 1956-04-03
Anticipated expiration: 1973-04-03
Also published as: GB747858A

Description

April 3, 1956 c. P. MAJKRzAK ELECTRON GUN Filed Nov. l.

INVENTOR CHA RLES MJKRZAK ATTORNEY therein.

United States Patent 11 Claims." (Cl. 313-82) This invention relatestoelectron gunsfand more particularly to the mechanical structure'and assembly of the electron gun.

The basic,.prblem found 1iny 4prior Varrangements of electron guns is `thatof holding can accurate alignment,

both axialand spaced, of anumber of insulated elec-` trodes of particular shapes.

Having inmind this basic problem, it isan object of my invention to provide a construction of electron vguns that lendsitself to accuracy andv toease of fabrication and assembly.

Another object of my invention is .to provide in the electron gun construction and arrangement Vthaticreates self-alignment for both the accelerating electrode subassembly and the cathode sub-assembly without an undue amount of jigging.

Still a further object of my invention is to provide a means of joining the two sub-assemblies into a nal'assembly that will require a minimum of skill .to obtain accuracy and a production line quantity output.

The .above-mentioned` and other features `and objects of this invention and the manner of 'attaining them will be best understood by reference `tothe following description of embodimentsof this invention takenin conjunction with the accompanying drawings, wherein:

Fig. ll is a longitudinal cross-section viewof an electron gun in accordancewith the principles of this invention;

Fig. 2 is a traverse Vcross-section yview along line 2--2 on Fig. l;

Fig; 3 is a longitudinal cross-section view of an elec tron gun showing a modified form of the invention;

Fig. 4 is a traverse cross-section view taken along line 4--4 in Fig. 3; and

Fig. 5 is an exploded view in cross-section of a detail in Fig. V3. r

Referring'to Figs. l and 2 ofthe drawing, one of the embodiments of my invention is shown which allows for accurate alignment of parts without an undue amount of jigging and expensive machinery. The ease of assembly is achieved by the fact that the electronV gun is constructed in two main sections, namely-the cathode section and the raccelerating electrode section. lThe cathode section has a housing member 1 cylindrical in shape with an inwardly extending flange 2. The accelerating electrode section also has a housing member 3 cylindrical in shape with an inwardly extending flange or shoulder 4, but hav-14 ing a smaller cross-section than that 'of housingl member 1.

ln assemblingthe cathode section, it is lirst desired to malte a cathodeV sub-assembly by inserting a ceramic washer'S into a small metallic cylinder 6 through which the lament .leads 7 are brought `by means of aperturesv These leads are connected to the filament coil S by means of soldering, brazing, or any other suitable method. Concentric With this arrangement isthen placed n a cathode element 9 which is spot welded orebrazed to cylinder 6 suchthat one of the ilamentleads 7 is welded or brazed at the same time to the interior of cylinder 6, such as at point 10. The cathode element 9 has its .25, 28, and 30 is received snugly therein.

2,740,913 Patented .Apta "3, Vv'11556 thermionic emitting surface located on a nipple, hereafter referredtozas the emittingV surface 11. Thissub=assembly .is `nextpositioned inandwelded or otherwise secured to Van annular. .shell 12.

A focusing electrode 14 in cupshape issecured to a ceramic washer 15,'and a lead 16 is connected thereto. The ceramic washer 15 is sandwiched between llange 2 and an annular element 17- spot welded or brazed .to

. housing member 1.

. VTo complete .the-assembly of thecathode section. a section ceramic washer18 having a larger interior-difarneter. than ceramic-washer l15 is sandwiched between theaelement17 andV aliange 19 .of a ring 20 welded or brazed towhousing member 1. This sandwiching is accomplished in such amanner that -the annularange '13 Yof shell 12 isfgrippetibetween ceramic washers V15 and .1S to hold the cathode element in proper alignment with aperture y21 located in `ceramic washer 15. The focusing electrodelead 16 is brought out through aperture 22 in ,theannularshell 12, the lead 16 being protected against .shorting `by ceramic .sleeve 23. A small amount of jigging is required to properly align cathode element 9 and its accompanying emitting surface 11 when the annular flangel 13 is being -sandwiched between

ceramic washers

15 and 18.

Stillreferring to Figs. l and 2 the electrode assembly -containedtin housing 3 will'now be described. lNozzleshaped tip 24 is spot welded or brazed to a third accelerat inglelectrode 25and then slipped into housing member 3 on top of a ceramic-spacer 26. Following this is ceramic `spacer'27, a.second accelerating electrode 28, another ceramic spacer 29,y followed by a first accelerating electrode 30 to which is spot welded or brazed a metallic focusing disc 31.

The

electrodes

25, 28, and 30 are of sheet stockeither stamped, punched, Vor turned. Each electrode hasa `in'thehousing member 3, while the interior dimension is such that the smaller end liange 33 of the electrodes It shouldalso be noted thatthe outer dimension of ceramic spacers 26,

l2'7., ,und'29 is larger than the dimension of electrodelateral flange 34. Therefore, the snug lit of the

ceramic spacers

26, 27, and 29 against housing member 3 plus the snug fit of the end flanges 33 of electrodes 25, 28, and 3tl, in ceramic spacers26, 27, and-29 hold said electrodes fin proper `axial and spaced alignment.

inthe process of inserting electrodes 25 and 28 in housing member 3, small stiff lead wires 35 and 35a are secured, as by spot welding, to the lateral projections'of the electrodes prior to inserting next element. Each lead wire is brought out of housing member 3 through au insulator 42. Y

To accomplish a completed assembly a stepped cylinder 36 having an inwardly extending flange 37 is used. Y

The smaller end of the cylinder 36 is telescoped into housing member 3, such that flange 37 is ilush against the projection 34 where it is spot welded to member 3 to hold vfirmly the

electrodes

25, 28, and 30 in desired alignment.

vHousing member 1 is then received in the larger end ofthe stepped cylinder 36 care being taken to line up apertures 38 in the tread portion of stepped cylinder 36 with apertures 39in ceramic Vwashers 15 and '18. Houslingmember lfisthen placed against Athetread portion of sembly leads 41 and 41a are disposed through

apertures

38 and 39, and from there to lead wires 35 and 35a.

Figs. 3, 4, and illustrate another form of this invention wherein the same reference characters are employed for identical parts as described in the foregoing embodiment.

In this embodiment cathode housing member 43 comprises a cylindrical shell having an inwardly extending tiange 44 that contains apertures 45 for leads 41 and 41a. Resting upon the flange 44 is a sheet of mica 48 containing two series of apertures 49 and 5f), also a central aperture 51 to expose emitting surface 11, and openings for alignment with openings 45 for passage of leads 41 and 41a. Annular shell 46 of the cathode assembly is secured in position by nipples 52 contained in an annular ring 53 extending through apertures 49 and spot welded. A focusing electrode 54 is held concentric to emitting surface 11 by an annular disc 55 containing nipples 56 which protrude through apertures 50 to which the electrode is secured by spot welds.

Housing member 3 and the ceramic spacers for the accelerating electrodes are identical to those used in the first embodiment. However, the third accelerating electrode 57 is a solid screw machine part shaped as shown in drawing. The second accelerating electrode 58 is similar to the second accelerating electrode 28 in Fig. 1 except that it is a screw machine part. The

ceramic spacers

26, 27, and 29 and accelerating

electrodes

57 and 58 are disposed in alternate manner and provided with the connections 35 and 35a.

First accelerating electrode 59 is a screw machine part that is provided with a reduced interior dimension 60 for concentrating the electron beam. The lateral fiange projection 61 is recessed to receive flange 37 to which it is welded. This unit is then telescoped with housing member 3, aligning apertures 38 with lead wires 35 and 35a and pressure applied prior to spot welding or brazing which then holds

electrodes

57, 58, and 59 in spaced and axial alignment.

The housing member 43 is inserted into the larger end of stepped cylinder 36 and

apertures

38, 62, and 45 are aligned. When this alignment is completed pressure is applied and the units are joined by spot welding or brazing. The pressure produced by the flange 44 and tread portion of stepped cylinder 36 clamps the mica sheet 48 in place, thereby providing the proper alignment between cathode element 9 and the accelerating

electrodes

57, 5S, and 59.

The focusing electrode potential is applied through lead i6, while the first accelerating electrode, 30 in the first embodiment and 49 in the second embodiment, is at ground potential through the stepped cylinder 36. Potentials of progressively higher values are applied through electrode leads 41, 35 and 41a, 35a to the second and third accelerating electrodes, respectively.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. Therefore, this description is made only by way of example and not as a limitation to the scope of my invention.

I claim:

l. in an electron gun, a cathode assembly comprising a cathode, a cylindrical shell, means supporting said cathode in said shell including an insulating element in the form of a sheet having apertures therethrough, means carried by said shell to support said element in position crosswise thereof, an annular plate disposed on one side of said insulating sheet, an annular shell to support said cathode on the other side of said sheet and means connecting said annular shell through certain of said apertures to said annular plate with said cathode exposed through still another' of said apertures, a focusing electrode closely adjacent to said cathode and means extending through apertures in said sheet to secure said focusing electrode thereto in concentric relation to said cathode.

2. An electron gun comprising a first housing member, a cathode, means supporting said cathode in said first housing member, a second housing member, a plurality of accelerating electrodes, means supporting said electrodes in alignment in said second housing member and means connecting together in a telescoping manner said first and second housing members to align said electrodes and said cathode, the means supporting said cathode including a sheet of insulating material having apertures therethrough, an annular plate disposed on one side of said insulating sheet, an annular shell to support said cathode on the other side of said sheet and means connecting said annular shell through certain of said apertures to said annular plate with said cathode exposed through still another of said apertures.

3. An electron gun according to claim 2, further including a focusing electrode disposed closely adjacent said cathode, and means extending through apertures in said sheet to secure said focusing electrode therethrough in concentric relation to said cathode.

4. An electron gun comprising a first housing member, a cathode, means supporting said cathode in said first housing member, a second housing member, a plurality of accelerating electrodes, means supporting said electrdes in alignment in said second housing member, and means connecting together in a telescoping manner and in tandem relation said first and second housing members to align said electrodes and said cathode, said plurality of electrodes each including a lateral projection and means supporting said electrodes in alignment including insulating spacers one each disposed between the projections of adjacent electrodes and between at least one of said adjacent electrodes and the wall of said second housing member, said first housing member comprising a shell and the means supporting said cathode including an insulating element and means carried by said shell to hold said element in position crosswise of said shell, said means carried by said shell including an inwardly extending flange, an annular element disposed laterally of said shell, said insulating element being in sheet form sandwiched between said fiange and said annular element having apertures therethrough, a focusing electrode, means extending through certain of the apertures in said sheet to secure said focusing electrode therethrough in concentric relation to said cathode, and means employing others of said apertures to support said cathode.

5. An electron gun comprising a first housing member having a first diameter and including an inwardly protruding end portion, a cathode, means supporting said cathode axially of said first housing member disposed crosswise said first housing member in contiguous relation to said protruding end portion, a second housing member having a second diameter and including a shoulder portion at one end thereof, a plurality of accelerating electrodes, insulating means disposed between adjaf cent ones of said electrodes and between one of said electrodes and said shoulder portion for positioning said electrodes axially of said second housing member, said first diameter being greater than said second diameter, and a connecting member to connect together said first and second housing members in an in line arrangement therewith, said connecting member including a first portion parallel to the axis of said housing members having an inwardly protruding end, a second portion parallel to the `axis of said housing members and a portion transverse to the axis of said housing members interconnecting said first and second portions, said first portion engaging the inner surface of said second housing member and said second portion engaging the outer surface of said first housing member to align the axes of said housing members and thereby align said electrodes with said cathode.

6. An electron gun according to claim 5, wherein the inwardly protruding end of said first portion engages one of said electrodes to cooperate with said insulating spacers and said shoulder portion to hold said electrodes in align ment with said cathode.

7. An electron gun according to claim 5, wherein said means supporting said cathode includes a sheet of insulating material, the transverse portion of said connecting member and the inwardly protruding end portion of said rst housing member cooperating to secure said sheet of insulating material in position crosswise said iirst housing member.

8. An electron gun comprising a rst housing member having an inwardly protruding end portion, a cathode, means supporting said cathode axially of said first housing member disposed crosswise said tirst housing member in contiguous relation to said protruding end portion, a second housing member having a shoulder portion iat one end thereof, a plurality of accelerating electrodes, insulating means disposed between adjacent ones of said electrodes and between one of said electrodes and said shoulder portion for positioning said electrodes axially of said second housing member, and a connecting member to connect together said irst and second housing members, said connecting member including a first portion parallel to the axis of said housing members having an inwardly protruding end, a second portion parallel to the axis of said housing members and a portion transverse to the axis of said housing members interconnecting said rst and second portions, said lirst portion engaging the inner surface of said second housing member and said second portion engaging the outer surface of said first housing member to align the axis of said housing members and thereby align said electrodes with said cathode, said means supporting said cathode including a sheet of insulating material, the transverse portion of said connecting member and the inwardly protruding end portion of said first housing member cooperating to secure said sheet of insulating material in position crosswise said trst housing member, said sheet of insulating material including a plurality of apertures therethrough and said means supporting said cathode further includes an annular plate disposed on one side of said sheet of insulating material, an annular shell to support said cathode on the other side of said sheet and means connecting said annular shell through certain of said apertures to said annular plate with said cathode exposed through still another of said apertures.

9. An electron gun according to claim 8, further including a focusing electrode disposed closely adjacent said cathode and means extending through other apertures in said sheet to secure said focusing electro-de thereto in concentric relation to said cathode.

l0. An electron gun according to claim 5, wherein said means supporting said cathode includes a rst disc of insulating material having an axial aperture therethrough, a. First inwardly protruding member carried by said first housing member, said disc being sandwiched between said first inwardly protruding member and said inwardly protruding end portion for positioning thereof, a second disc of insulating material, a second inwardly protruding member carried by said iirst housing member, a iianged cylinder with the outwardly extending flange thereof sandwiched between said iirst and second discs, said second inwardly protruding member cooperating to hold said second disc in position crosswise said rst housing member `and means to support said cathode in said flanged cylinder in alignment with said axial aperture.

11. An electron gun according to claim 10, further including a focusing electrode carried by said lirst disc in concentric relation with respect to said axial aperture.

References Cited in the le of this patent UNITED STATES PATENTS 2,093,876 Von Ardenne Sept, 2l, 1937 2,163,740 Wales June 27, 1939 2,170,663 Painter Aug. 22, 1939 2,184,821 Uhlmann Dec. 26, 1939 2,185,807 Gabor et al Jan. 2, 1940 2,227,051 Wienecke Dec. 31, 1940 2,244,358 Ewald June 3, 1941 2,248,558 Schlesinger July 8, 1941 2,268,165 Parker et al Dec. 30, 1941 2,279,249 Roman Apr. 7, 1942 2,282,392 Bieling May 12, 1942 2,313,018 Krause Mar. 2, 1943 2,411,913 Pierce et al. Dec. 3, 1946 2,436,265 Pohle et al. Feb. 17, 1948 2,441,315 Forgue May 11, 1948 2,462,921 Taylor Mar. 1, 1949 2,468,136 Taylor Apr. 26, 1949 2,521,364 Haller Sept. 5, 1950 2,540,621 Johnson Feb. 6, 1951 2,569,847 Eitel et al. Oct. 2, 1951