US2850663A

US2850663A - Planar tube

Info

Publication number: US2850663A
Application number: US511531A
Authority: US
Inventors: David R Weindorf
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1955-05-27
Filing date: 1955-05-27
Publication date: 1958-09-02
Anticipated expiration: 1975-09-02

Description

Sept. 2, 1958 D. R. WEINDORF 'PLANAR TUBE Filed y 27, 1955 FIG. 2

FIG. 3

INVENTOR DA V10 1?. WEINpoR FIG. I

7 ATTORNEY F nitecl States PLANAR TUBE Application May 27, 1955, Serial No. 511,531

Claims. (Cl. 313-257) This invention relates to electron discharge tubes, and more particularly to an improved construction of the type known as planar tubes, and the method of making tubes of this type.

In conventional planar tubes, the grid or grids and the anode of the tube are mounted within a glass envelope by means of support rods extending from a glass base, and are positioned with respect to one another by ceramic spacers. The glass envelope is hermetically sealed to the glass base, thus providing for a vacuum tight enclosure.

Another known construction of a planar tube utilizes a glass base, and a glass envelope, the walls of which have hermetically sealed therein the support elements for the tube electrodes. These electrodes are spaced from one another and held in position by the glass envelope wall.

These conventional planar tube structures are difiicult to fabricate and therefore expensive to produce. The difficulties arise primarily from the inherent fragility of glass and the numerous glass to metal seals which are required, since it is often necessary, in a multi-element tube, that a number of seals be made independent of one another and at closely spaced positions. The heat necessary to provide for a satisfactory seal at one position affects adjacent seals, and produces undesirable strains in the surrounding glass. These difliculties are highly magnified in present day electron tube constructions, since the tendency is in the direction of decreasing the dimensions of the tube. It is not uncommon to produce planar tubes having overall dimensions no larger than one-half an inch. Therefore, the heat needed to produce any of the seals, even though the heat source is highly concentrated, cannot be so restricted to an area so as not to afiect adjacent seals.

Resolving the aforementioned difiiculties, it is apparent that a desirablestructure for a stacked tube would comprise elements which are physically rugged and compact, are made of similar materials which are inherently dimensionally stable under high temperatures, and are of configuration requiring a minimum number of sealing operations. In addition, these structures must be adaptable to efficient automatic production methods.

The present invention provides for a planar tube which has the aforementioned advantages. Accordingly, an object of this invention is to provide for a planar tube which is small, compact, and rugged.

Another object of this invention is the provision of an electron discharge device adaptable for automatic production.

A further object of this invention is the utilization of ceramic materials for tube elements and which are not affected by heat to an undesirable extent, some of these ceramic materials having the function of forming part of the enclosure for the electrode elements.

A still further object of the invention is the provision of a planar electron tube wherein the spacer elements for atent G "ice the electrodes of the tube have co-extensive outside surfaces, and a common seal.

A still further object of the invention is to provide a method of making a planar electron tube wherein a minimum number of sealing operations produces a completed vacuum tight enclosure.

The foregoing objects, as well as additional objects, which will be apparent after reading the following description, are attained by the provision of an electron discharge tube which employs ceramics for support structures and spacers rather than glass, since ceramics are inherently dimensionally stable under the high temperatures needed to produce adequate hermetic seals between the various elements during the process of constructing the tube. The novel structure of the present invention utilizes essentially a cathode mounted upon an anode ceramic spacer, and a grid electrode positioned intermediate the cathode and anode by means of the ceramic base member and a ceramic grid spacer. These elements are circular in shape and have equal diameter so that their outside surfaces are co-extensive. A single seal hermetically encloses the base member, grid electrode, grid spacer, and anode spacer along the co-extensiye surface. Surrounding the seal is a metal sleeve which serves as a securing device for these elements in addition to providing for an external grid connection. The final seal of the anode to the anode spacer is made by an anode conductor plate, and in one embodiment of the invention, an exhaust tubulation. The parts constituting the electron discharge tubes are stacked upon one another in proper sequence, the sealing mediums are positioned adjacent the parts to be sealed, and the assembly is heated to fuse the sealing medium. The assembled tube is subsequently evacuated.

The present invention will be more fully understood by reference to the following detailed description taken in conjunction with the accompanying drawings in which Fig. 1 is a view in section of one embodiment of the planar electron tube constituting the invention.

Fig. 2 is a section through Fig. 1 on the line 22, and

Fig. 3 is a view in section of another embodiment of the planar tube constituting the invention.

Referring to Fig. 1, a base member 11 of ceramic such as Zircon Porcelain, has mounted thereon a filamentary cathode 13. The base member comprises a cylindrical wall 15 and an internal platform 17 having a central depression 19 and an annular rim 21. The platform is spaced from the Wall 15 at its upper portion by channel 23 and is integral with the wall at its lower portion. Filamentary cathode 13 is bridged across rim 21, with both of its ends extending into channel 23. One end of the cathode is attached to filament lead 27 by means of tab 25 and connectors 29. The other end of the cathode is connected to filament lead 27 by means of tensioning device 31. These cathode connections may be made in any suitable manner, such as by welding. The filament leads 27 extend through the base member 11, thereby providing for the external filament electrical connections. A circular metallic grid disc or annulus 33 having grid wires 35 mounted thereon, is flush with the end of cylindrical wall 15 and overlies the opening in channel 23. The grid annulus has an inside diameter greater than the diameter of platform 17, thereby providing a space through which the cathode may pass. Abutting the planar surface of grid disc 33, opposite base member 11, is a metallic grid spacer 37, whose outside diameter is equal to the outside diameter of the grid disc. The surface of grid spacer 37 opposite the grid disc abuts an annular anode spacer 39 of a ceramic material, such as Zircon Porcelain. The outside diameter of the anode being L- shaped in cross-section. The outside diameter of the horizontal section spacer is equal to the outside diameter of the grid spacer 37. Therefore, the outside sur- V 'are equal, thereby forming ace-extensive surface.

faces of'base member 11, grid 'disc '33ygrid *spacer 37, andanode spacer 39 define a cylindrical co-extensive surface. A metallic anode connector plate 41 is positioned against the endoffthe verticalsecti'on of spacer '39 and may be attached to: a metallicfexhaust tubulation 43 "bya'brazed on'retaining ring44. Preferably; ring 44 is a split ring of tungsten wire' which'is forced over the exits spring action on the exhaust tubulation'43. Connected to the lower open end "of tubulation 43is' themetallic anode-disc 45. Near the'center of the anode is a port 47 providing an opening through which theassembled tube maybe-evacuated. The'anode isipositioned .withrespect for 'thei'getter. A cut-out portion 56 in the rim 21 provides for passage of thegetter bar across the-depression 19. Pig. Zillustrates theiposition of the getter bar with resp'ect:to the filament 13. The getter flash is directed downwardly into the depression 19, and away from the filament. The end'of' the getter bar opposite tab 55 is connected to getter tab53, which extends across channel '23 and contacts the undersideoffg'rid disc 33. This contact'provides the getter.

second electrical connection for the V V haust tubulation and holds'plate '41 in'place by virtue of 7 tateexhausting the electron tube 'assemb'ly through an aperture 89 in the anode." An anode contact plate 91 is attached to lip 85 of anode support 80 by means of solder ring 533. On the inner'surface of the contact plate is embedded a getter 95.

Sealing mediums

81, 83, and 85 support and hermeticallyseal the metallic and ceramic elements associatedtherewith. Sealing medium 81 traverses the co-extensive surface formed by base member 64,.grid disc 73, grid spacer 75 and anode spacer'77. V 7

Referring tothe planar tube shown in Fig. l, the method of assembling the. elements of the tube is as follows. The ceramic base member llandanodespacer 39 are painted or-otherwisecoated with a Wetting agent such as 'a suspension of titaniurn hydride in a nitrocellulose lacquer. welding cathode 13 to tensioning device 31 on one end and connector 29 on the other. Cylinders-6 0 are slipped over the filament leads 2 7, andsa high puritylead sealingring is positionedwithin the cylinders and adacent the leads. The getter tab 55 is welded to getter lead 57.

An anode sub-assembly is constructed by welding anode plate. to the tubulation 43 and threading tubulation Lithrough the aperture in anode spacer 39 until the plate engages'anode spacer 39; then the 'highpurity lead sealing ring 61' isplaced between the anode spacer and exaust tubulation, and plate 41 isattached tothe tubulation by means of a ring 44.

The filament leads 27 are hermetrically sealed to base member'il bya solderrings'ealing medium 59' such'as a high purity lead confined within the walls of cylinders tl.

Exhaust tubulation '43 is hermetically sealed: to anode spacer 39 by a similar sealing medium 61, and the coextensive surfaces of base member 11, grid disc 33,- grid spacer 37," and anode .spacer- 39 are also. hermetically l sealed with'one another by a high purity leadsealing me dium 63. V V

Theelectrical'leads for filament 13 areprovided by l'eads2'7. 'ihegrid connection and one getter connection is imaderby means of grid disc.33, lead solder 63, and

sleeve 49. The second'c onnection for the getter is provided by lead 57. The anode connection is made by the metal. exhaust tubulation 43 and anode connector plate 41.

Fig. 3 shows another embodiment of a planar electron mountedthereon by means of a tab67on-one end and a tensioning device 69 on the other. The filament connections are made by leads 71. A'grid -disc 73'ispositioned between the-base member 64 and a-grid spacer 75, this spacer abutting an anode spacer 77 on'the surface opposite the grid disc 73. The outside diameters'of the base member, grid disc, gridspacer, and anode spacer They are surrounded by metallic sleeve 79; which also serves as the electrical -connection for the grid. Between the sleeve and the co-extensive'surface is a'high purity lead hermetic sealing medium 81. The sealing mediur'n 83 for thefilament leads has the same type of sealing composition as above.

' tanium hydride decomposesandithe'leadsealingmediums The sub-assemblies and 1 other elements-of the tube are then assembled in a suitable" holding device or jig so thatthe exhaust tubulation is in a downward position. The anode sub-assembly is threaded through the aperture in sleeve 49 and is positioned with ithe tano de spacer abutting shoulder 51. Grid spacer 37, grid disc 33','and the cathode sub-assembly isFstacked upon the anode subassernbly, and a high purityqleadisolder ring is placed;

within the confines of sleeve 49. The free endq58 of getter bar 53 -is slipped between-griddisc233 and base 7 member 11. The final step in the assemblyprocessyis the fusing and hermetic sealingoperationzwhereinthe' parts are rigidly affixed to one another. .Thefentire tube isheated in a vacuumor-in'a chamber'provided with a non-oxidizing; gas such ;as argon" orfhydrogeni to atemperature of -.approximately800 centrigr'adezby: any: suit. able means,;-such .as an

induction coilywher'eat'the ti

59, 61, and 63 wet the ceramicawherebyfusion between the. sealing medium'and the. metallic 'el'ementsassociated therewith occurs. After assembly thei tubeicanf be .processedand evacuated in a conventional manner.

The cathode sub-assembly ofithe planar-tube: shown in Fig. 3 is made in the same manner as describedHfor'the tube wherein a ceramic base member'64 has a filament 65 7 embodiment shown in Fig. 1. iThe anode' sub assembly is constructed by placing" support cup 80 within the aper ture in anode spacer 77,:slipping 'asealin'g 'ring'86 be-' tween the cup and anode Fspacer-walls, and welding anode 82 to the base of the cup. :The'anode "spacer is thereby confined between lip '85 and anode 82.

The sub-assemblies and other elements-of the tube are assembled in an 1 inverted :position. Ihe anodei-gs'ubassembly is threaded through the' aperture -in sleeve' 81 and rests upon the sleeve shoulder and upon solder ring 93and getterplate91. Grid spacer 75, giiddisc 73,and

Acup-sbapedmetallic' anode support"8tl*positions the V anode 82 by means of aconnectionbetween' the base 84-2 of' the cup and the ano de, andby means of the lip 85 of'the cup cooperating with anodespacer 77. The

. 'Itis' apparent fromthe foregoingjthat the'planar tubes 7 7 described herein are ruggedly constructed and adaptable the cathode sub-assembly is" then stacked upo'n the anode sub-assembly in 1 sequence. A high purity leadsealing ring is then positioned within the confines-ofsleeve 81. This assembly is placed within a vacuum bell-jar,- and after evacuation; the entire tube is heated "to-- causefa simultaneous fusion of s ealing'medium 81, '83, fland-*8ti with their {associated metallic and -ceramic elements. A. concentrated radio frequency coil'"fus'essolder 93 'with etter Plate91fand-cup arid-al fla sg 1 to complete the operation. I a

A cathode sub-assembly is formed by for automatic production. The co-extensive peripheral surface defined by the base member, grid disc, and grid and anode spacers provide a simple and effective means whereby these elements may be rigidly atfixed and hermetically sealed to one another. In addition, the heating operations required to completely fuse and seal the structures into a unitary assembly are performed in such a manner that none of the previously made connections are adversly affected by the operation. Also, the use of Zircon Porcelain ceramic, titanium hydride, and a high purity lead solder provides an efiicient and effective means for attaching, positioning, and sealing the electrodes with one another, and alleviates the serious glass strain difficulty previously experienced when several independent glass to metal seals had to be made by the application of heat at closely spaced positions. However, these material compositions were only recited as examples. Althrough several embodiments of the invention have been shown and several methods of assembly described, it is to be understood that other modifications will be obvious to one skilled in the art, and that these modifications are within the scope of the invention.

What is claimed is:

1. An electron discharge device including a cathode mounted upon a base member, and an anode mounted upon an anode spacer, said member and anode spacer having co-extensive outside surfaces and a common hermetic seal for said member and spacer, said seal being in contact with said coextensive outside surfaces and spanning the juncture between said member and spacer.

2. An electron discharge device including a cathode mounted upon a ceramic base member, and an anode mounted upon an anode ceramic spacer, said base member and anode spacer having co-extensive outside surfaces and a common hermetic seal for said member and spacer, said seal being in contact with said coextensive outside surfaces and spanning the juncture between said member and spacer.

3. An electron discharge device including a zircon base member having a cathode mounted thereon, and an anode mounted upon a zircon anode spacer, said base member and anode spacer having co-extensive outside surfaces and a common hermetic seal for said member and spacer, said seal being in contact with said coextensive outside surfaces and spanning the juncture between said member and spacer, said seal being of a composition comprising a high purity lead solder.

4. An electron discharge device including a base member having a cathode mounted thereon, an anode spacer, an anode mounted upon said spacer, at least one grid electrode, and at least one grid spacer, said grid electrode being positioned intermediate the cathode and anode by means of said base member and the grid spacer, said base member, grid electrode, grid spacer, and anode spacer all having a common hermetic seal, said seal comprising a single band of sealing material surrounding and bonded to peripheral surfaces of said members, electrode and spacers.

5. An electron discharge device including a ceramic base member having a cathode mounted thereon, a ceramic anode spacer, an anode mounted upon said spacer, at least one grid electrode, and at least one grid spacer, said grid electrode being positioned intermediate the cathode and anode by means of said base member and the grid spacer, said base member, grid electrode, grid spacer, and anode spacer all having a common hermetic seal, said seal comprising a single band of sealing mate rial surrounding and bonded to peripheral surfaces of said members, electrode and spacers.

6. An electron discharge device including a base member having a cathode mounted thereon, an anode spacer, an anode mounted upon said spacer, at least one grid electrode, and at least one grid spacer, said grid electrode being positioned intermediate the cathode and anode by means of said base member and the grid spacer, said base member, grid electrode, gr?! spacer, and anode spacer all having co-extensive outside surfaces and a common hermetic seal, said seal comprising a single band of sealing material surrounding and bonded to peripheral surfaces of said members, electrode and spacers.

7. An electron discharge device including a base member having a cathode mounted thereon, an anode spacer, an anode mounted upon said spacer, at least one grid electrode, and at least one grid spacer, said grid electrode being positioned intermediate the cathode and anode by means of said base member and the grid spacer, said base member, grid electrode, grid spacer, and an anode spacer all having circular co-extensive outside surfaces and a common hermetic seal, said seal comprising a single band of sealing material surrounding and bonded to peripheral surfaces of said members, electrode and spacers.

8. An electron discharge device including a base member having a cathode mounted thereon, an anode spacer, an anode mounted upon said spacer, at least one grid electrode, at least one grid spacer, and a metal sleeve, said grid electrode being positioned intermediate the cathode and anode by means of said base member and the grid spacer, said base member, grid electrode, grid spacer, and an anode spacer all having circular co-extensive outside surfaces and a common hermetic seal Within the confines of said metal sleeve, said metal sleeve surrounding the said circular surfaces and being spaced therefrom by said hermetic seal.

9. An electron discharge device including a base member having a cathode mounted thereon, an anode spacer, an anode mounted upon said spacer, at least one grid electrode, at least one grid spacer, and an exhaust tubulation, said grid electrode being positioned intermediate the cathode and anode by means of said base member and the grid spacer, the base member, grid electrode, grid spacer, and anode spacer having co-extensive outside surfaces and a single common seal spanning the junctures between said base member, grid electrode, grid spacer, and anode spacer, and the anode spacer and exhaust tubulation having a single common seal.

10. An electron discharge device including a base member having a cathode mounted thereon, at least one grid electrode, at least one grid spacer, an anode, an anode spacer, and an anode support member, the anode being mounted upon said anode spacer by means of the anode support member, said grid electrode being positioned intermediate the cathode and anode by means of said base member and the grid spacer, the base member, grid electrode, grid spacer, and anode spacer having coextensive outside surfaces and a single common seal spanning the junctures betwen said base member, grid electrode, grid spacer, and anode spacer, and said anode spacer and anode support having a single common seal.

References Cited in the file of this patent UNITED STATES PATENTS 1,561,249 Krant Nov. 10, 1925 2,173,906 Katsch Sept. 26, 1939 2,228,157 Steenbeck Jan. 7, 1941 2,425,593 Brian Aug. 12, 1947 2,459,277 Halstead, et al Jan. 18, 1949 2,647,218 Sorg et a1. July 8, 1953 2,719,185 Sorg et al Sept. 27, 1955 2,731,578 McCullough Jan. 17, 1956 FOREIGN PATENTS 167,268 Austria Dec. 11, 1950 OTHER REFERENCES Materials Technology for Electronic Tubes, Kohl, 1951, pages 319, 372.