US3821589A - Storage cathode particularly a mk cathode - Google Patents

Storage cathode particularly a mk cathode Download PDF

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Publication number
US3821589A
US3821589A US00339325A US33932573A US3821589A US 3821589 A US3821589 A US 3821589A US 00339325 A US00339325 A US 00339325A US 33932573 A US33932573 A US 33932573A US 3821589 A US3821589 A US 3821589A
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United States
Prior art keywords
porous plate
column
disc
dispenser cathode
container
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00339325A
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English (en)
Inventor
H Katz
E Huebner
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Siemens AG
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Siemens AG
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Filing date
Publication date
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Publication of US3821589A publication Critical patent/US3821589A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
    • H01J1/28—Dispenser-type cathodes, e.g. L-cathode

Definitions

  • the cathode structure comprises a cylindrical container, open at one side, adapted to form a supply chamber for a charge of emission-promoting material, with the open side of the container being vclosed by a porous plate tightly sealed thereto, having a threaded bore therein adapted to mate with a threaded central column extending from one side of a solid disc of refractory-metal, which has a similar central column at the opposite side thereof, which carries an insulated heater.
  • the cylindrical container is provided with a wad of tungsten wire disposed adjacent the porous plate, and the heater is adapted to be secured to the second column of said disc by a cement sintered thereon in a high temperature operation.
  • the wad of tungsten is initially disposed in the cylindrical container and the porous plate secured thereto, for example by welding, to form a sub-assembly, and in like manner the heater is secured to the second column by means of a cement, utilizing a sintering operation, with the two sub-assemblies, following insertion of the 5 charge of emission-promoting material through said bore, into said container the latter is threaded on said threaded column, with an edge of the cylindrical container bearing on said solid disc to form a seal therebetween.
  • the invention is directed to dispenser cathodes, and particularly metal-capillary cathodes, in which a charge of emission-promoting material is contained in a storage chamber and enclosed in part, by a porous tungsten plate which constitutes the active emitting surface, the active surface, if desired being provided with an additional metal coating of one or more metals such as rhenium. osmium or the like.
  • barium oxide is utilized as the primary supply material, in lieu of barium which is conventionally usedas an emission-promoting material, because the advantage offered by its ready action in a convenient temperature change.
  • barium oxide has the disadvantage of being hygroscopic and thus subject to reaction with other atmospheric components, which may lead to considerable difficulties during manufacture. For example, the formation of barium hydroxide in the presence of humidity may present a number of problems.
  • British Patent No. 1,269,028 discloses a dispenser cathode especially designed for electron discharge tubes, which however, is of relatively large dimensions, utilizing a porous carrier plate mounted on a cathode body in which cup-shaped screw-plugs provided with closures contain the supply material and act as storage containers in conjunction with a sealing foil.
  • the construction is such that the foil releases the supply material only when the cathode is initially operated in its discharge tube, as a result of the foil either bursting during evacuation or is held by a paraffin-wax edge seal that is broken.
  • This construction has achieved outstandingly good results in cathodes involving relatively large dimensions, but would be far too expensive for cathodes of significantly smaller dimensions, as are now required, for example, in camera tubes and picture display tubes.
  • the present invention therefor among its objects the production of a dispenser cathode construction comprising, for example, two component sub-assemblies which can be stored indefinitely, and the assembly of which can be effected in a very simple manner without any thermal treatment, immediately prior to complete assembly.
  • the cathode structure of the present invention comprises a cylindrical container which forms the supply chamber, with the container being tightly sealed to a porous plate to form a sub-assembly, while a second sub-assembly comprises a solid disc of refractory metal having a central threaded projection or column extending from one side thereof and a central projection or column extending from the other side thereof, the latter projection having mounted thereon an insulated heater that is secured thereto by means of a cement that has been sintered thereon in a high temperature operation.
  • the cylindrical container is provided with a bore therein at the side opposite to that secured to the porous plate, which bore is of a size to form the receiving opening for the insertion of the charge of emission-promoting material into the container, which bore is provided with internal thread adapted to mate with the thread on the first mentioned central column.
  • This type of construction provides a closure element which is relatively extremely simple to manufacture and does not require any special precision. Since the sub-assembly, including the solid plate and central column, may be manufactured in the form of an integral structure, difficulties heretofore associated with the provision of small hollow cavities and peripheral threading are avoided.
  • a very simple construction can be achieved by the utilization of a single threaded rod or stud, secured in hermetically sealed'relation to the solid disc by means of a conventional hightemperature soldering operation.
  • the perimeter of the solid disc provides a readily available surface for mounting a heat-reflecting and mounting foil cylinder, which may be so secured thereto that the cylinder does not come into thermally conductive contact with the attached heater assembly or with the' cathode body and its porous plate.
  • FIGURE illustrates a generally sectional view of a cathode structure embodying the present invention.
  • a solid disc 1 of a refractory metal such as molybdenum
  • a central rod or stud having a portion 2 at one side of the disc 1 and an elongated portion forming a central column 3 at the opposite side of the disc.
  • the column 3 has mounted thereon an insulated heater 4, which in the example illustrated is secured thereto by a mass of heater cement 5, adapted to be sintered at high temperature, to unit the parts into a sub-assembly which includes the solid disc 1 and the screw portion 2, and which may be readily manufactured and indefinitely stored.
  • a second subassembly comprising a cylindrical member 6 likewise made of a refractory metal such as molybdenum, which is provided with a central threaded bore 7. Both end faces of such cylindrical members are beveled, with the end face 8 having a concave configuration providing a relatively sharp outer edge, whilethe opposite end face 9 is convex, forming relatively sharp inner edge. Disposed at the concave face 8 and engaged with the relatively sharp outer edge thereof, in sealed relation, is a porous plate 10 of tungsten which can be readily secured to the member 6 by welding.
  • a wad of tungsten wire Positioned between the concave end face 8 and the inner face of the tungsten plate 10 is a wad of tungsten wire, and disposed in the threaded bore 7 is a charge of emission material 12, whereby the tungsten wire 1 1 is interposed between the charge 12 and the tungsten plate 10.
  • supply chamber formed by the member 6 for the emission material 12, as in the case of the first subassembly described, can be manufactured and stored to a high temperature treatment, for example, in a reducing atmosphere.
  • the tungsten plate can be chemically coated with osmium, which involves a reduction process at elevated temperature.
  • osmium layer can also be alloyed into the structure of the tungsten plate, e.g., at 1,300C, which greatly enhances the future reliability of the emission properties of the structure.
  • the plate can be suitably sealed with respect to the passage of gas until it is put into operation.
  • the respective and, if desired, additionally treated subassembly respectively consisting of the cylindrical member 6, carrier plate 10 and tungsten wad 11, and the other sub-assembly comprising the disc 1, projections or columns 2 and 3, as well as the heater 4 and cement 5, may be assembled following insertion of a charge tablet 12 of emission-promoting material into the bore 7.
  • the threaded portion 2 is then inserted in the bore 7 and the container 6 screwed down thereon to provide the necessary sealing action and as a result of engagement of the inner edge of the convex end space 9 with the adjacent face of the solid disc 1, a very effective seal can be achieved.
  • a heat reflecting radiation-shield foil cylinder 13 which advantageously may simultaneously serve as the mounting support for the cathode system, may be welded to the outer cylindrical periphery 14 of the solid disc 1.
  • Such radiation shield has no direct thermally conductive contact with either the heater or the porous carrier plate, whereby it can be mounted at an early stage if desired, and in operation, its temperature is substantially lower than that of a conventional assembly.
  • the utilization of-the column 3 provides a particularly efficient conductive transmission of heat directly from the heater to the upper cathode structure, whereby excellent thermal characteristics are achieved.
  • a dispenser cathode of the type in which emission-promoting material passes from a supply chamber through a porous plate covering the latter to form an active emitting surface the combination of a cylindrical container, open at one side, and forming a supply chamber for a charge of emission-promoting material, a porous plate closing said open side and tightly sealed to said container, the latter having a bore therein extending to the opposite side thereof, said bore communicating with said chamber and of a size to permit passage of said charge from said opposite end into said chamber, a solid disc of refractory metal having a cenof said chamber, and an insulated heater secured to the column at the opposite side of said disc by a cement sintered thereon.
  • a dispenser cathode according to claim 1 comprising in further combination an outer heat-reflecting and supporting foil cylinder attached to the periphery of said solid disc.
  • a dispenser cathode in which said supply container is in the form of a generally cylindrical body with a central internal threaded bore, and has a concave end surface providing a relatively sharp outer edge to which said porous plate is attached, the other end surface of said container being convex, providing a centrally disposed relatively sharp edge bearing upon said solid plate.
  • a dispenser cathode according to claim 1 in which a wad of tungsten wire is disposed between said emission material and said porous plate.
  • a dispenser cathode according to claim 14, com prising in further combination an outer heat-reflecting and supporting foil cylinder attached to the periphery of said solid disc, said cylinder being spaced from and out of direct thermally conductive contact with both said heater assembly and said porous plate.

Landscapes

  • Solid Thermionic Cathode (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Secondary Cells (AREA)
US00339325A 1972-03-29 1973-03-08 Storage cathode particularly a mk cathode Expired - Lifetime US3821589A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2215477A DE2215477C3 (de) 1972-03-29 1972-03-29 Vorratskathode, insbesondere MK-Kathode

Publications (1)

Publication Number Publication Date
US3821589A true US3821589A (en) 1974-06-28

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ID=5840592

Family Applications (1)

Application Number Title Priority Date Filing Date
US00339325A Expired - Lifetime US3821589A (en) 1972-03-29 1973-03-08 Storage cathode particularly a mk cathode

Country Status (6)

Country Link
US (1) US3821589A (de)
CA (1) CA1012600A (de)
DE (1) DE2215477C3 (de)
FR (1) FR2177716B1 (de)
GB (1) GB1404473A (de)
IT (1) IT981639B (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3627384A1 (de) * 1986-08-12 1988-02-18 Siemens Ag Indirekt geheizte vorratskathode, insbesondere metall-kapillar-kathode, fuer elektrische entladungsgefaesse
EP0311501A1 (de) * 1987-10-09 1989-04-12 Thomson-Csf Strapazierfähige Oxidkathode für Kathodenstrahlröhren
US5172030A (en) * 1988-01-20 1992-12-15 Eev Limited Magnetron
US6570339B1 (en) 2001-12-19 2003-05-27 Chad Byron Moore Color fiber-based plasma display

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2050045A (en) * 1979-05-29 1980-12-31 Emi Varian Ltd Thermionic cathode
JPS6036056B2 (ja) * 1979-06-21 1985-08-17 株式会社東芝 陰極構体

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3627384A1 (de) * 1986-08-12 1988-02-18 Siemens Ag Indirekt geheizte vorratskathode, insbesondere metall-kapillar-kathode, fuer elektrische entladungsgefaesse
US4803397A (en) * 1986-08-12 1989-02-07 Siemens Aktiengesellschaft Indirectly heated dispenser metal capillary cathode for electrical discharge devices
EP0311501A1 (de) * 1987-10-09 1989-04-12 Thomson-Csf Strapazierfähige Oxidkathode für Kathodenstrahlröhren
FR2621735A1 (fr) * 1987-10-09 1989-04-14 Thomson Csf Cathode a oxydes robuste pour tube a rayons cathodiques
US4912362A (en) * 1987-10-09 1990-03-27 Thomson-Csf Sturdy oxide cathode for cathode ray tube
US5172030A (en) * 1988-01-20 1992-12-15 Eev Limited Magnetron
US6570339B1 (en) 2001-12-19 2003-05-27 Chad Byron Moore Color fiber-based plasma display

Also Published As

Publication number Publication date
IT981639B (it) 1974-10-10
GB1404473A (en) 1975-08-28
DE2215477B2 (de) 1974-08-08
DE2215477A1 (de) 1973-10-11
CA1012600A (en) 1977-06-21
DE2215477C3 (de) 1975-04-10
FR2177716A1 (de) 1973-11-09
FR2177716B1 (de) 1976-08-27

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