US3192005A - Method of fabricating a cathode ray tube - Google Patents

Method of fabricating a cathode ray tube Download PDF

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Publication number
US3192005A
US3192005A US227272A US22727262A US3192005A US 3192005 A US3192005 A US 3192005A US 227272 A US227272 A US 227272A US 22727262 A US22727262 A US 22727262A US 3192005 A US3192005 A US 3192005A
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US
United States
Prior art keywords
cathode
grid
coating
wall
cup
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
Application number
US227272A
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English (en)
Inventor
Linn Donald Max
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to NL298574D priority Critical patent/NL298574A/xx
Priority to BE637906D priority patent/BE637906A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US227272A priority patent/US3192005A/en
Priority to GB36427/63A priority patent/GB974557A/en
Priority to DER36140A priority patent/DE1237697B/de
Priority to FR949082A priority patent/FR1371496A/fr
Application granted granted Critical
Publication of US3192005A publication Critical patent/US3192005A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/485—Construction of the gun or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/18—Assembling together the component parts of electrode systems

Definitions

  • Electron guns of cathode ray tubes used, for example, in home television receivers usually comprise a plurality of axially aligned electrodes. These electrodes include a centrally apertured control grid cup and a tubular cathode having an end wall coated with electron emissive material and closely spaced opposite the aperture of the grid cup. Only a small central portion of the cathode emissive wall overlies the grid aperture and emits electrons which contribtue to the formation of the electron beam. In some tubes, such as commercial types 19AIP4, 19CHP4, '19CKP4, and 23DAP4, the cathode-to-control grid spacing may be only a few mils. In other types of tubes of the so-called low drive variety, the cathode-to-control grid spacing may be even less than a mil. Often times the cathode coating, which comprises a mixture of powders, is of irregular thickness and includes peaks.
  • the end wall of a tubular cathode is first bulged or domed outwardly and is'then coated with a suitable electron emissive material.
  • the cathode is then mounted relative to the control grid and is fixed in selected spaced relationship therewith.
  • the domed characteristic. of the emissively coated cathode .wall the peripheral areas of the emissive coating are spaced farther from the control grid than is the central portion of the coating which overlies the control grid aperture.
  • FIG. 1 is a side elevation view partly in section and with parts broken away' of a cathode ray'tube embodying the invention; and a FIG. 2 is an enlarged detail in section of the cathode ray tube of FIG. '1.
  • 4 i Y The invention may be embodied in fabricating a cath- 19 may be of any suitable type such as one comprising a layer 20 of a phosphor material on the faceplate with a. superimposed film 21 of evaporated aluminum thereupon.
  • the electron gun 18 comprises a plurality of coaxial, tubular, centrally-apertured electrodes including a control electrode cup 22, a screen electrode cup 24, and a focussing system including a first anode 26, a focussing ring 28, and a second anode 30. These electrodes are mounted in coaxial spaced relationship along a pair of insulator rods 32 by U-shaped mounting studs 34 which are fixed to the electrodes and embedded in the insulator rods.
  • a cathode assembly 35 which includes a tubular cathode 36 mounted in a centrally apertured insulator disk 33, e.g., a ceramic washer, is coaxially mounted within the control electrode cup 22.
  • the cathode 36 is closed at one end with a dome-shaped end wall 40 which is coated with suitable materials to provide an electron emissive surface.
  • a heater filament 41 is provided within the tubular cathode 36.
  • a conductive coating 42 on the internal surface of the funnel 16 is connected to the luminescent screen 19 and to the second anode 30 through a plurality of spring snubbers 44 attached'to the second anode.
  • a high voltage contact terminal indicated schematically by the arrow 46 is provided for applying a suitable voltageto the coating 42, the anode 30, the phosphor screen 19, and the anode 26 which may be connected (not shown) to the anode 30 internally of the tube.
  • the neck 12 is closed at its distal end with a stern structure (not shown) over which a base 48 is fixed.
  • a plurality of lead-in conductors 50 for applying suitable voltages to electrodes of the electron gun 18 are scaled through the stern and extend through the base 48.
  • the control grid cup'22 comprises acylindrical wall 51 which is closed at one end with a planar wall 52
  • the end wall 52 has an electron beam aperture 54 centrally thereof.
  • the cathode assembly 35 comprises the cathode36, the ceramic washer 38, and a pair of flanged retaining rims 56 and 58.
  • the tubular cathode 36 is secured within the central aperture of the ceramic washer 38by a pair of circumferentially crimped beads 60 which are flattened against the opposite faces of :the Washer.
  • the ceramic washer 38 is .held captive between the flanges of the flanged outer rim 56 and the flanged inner rim'58 which fits snuggly radially within the outer rim 56 and which is fixed thereto such as by welding.
  • the end wall 40 of the cathode is provided with a coating 61 of suitable electron emissive material.
  • the cathode assembly 35 is positioned as a unit within the grid cup 22 to obtain a desired spacing of the domeshaped end wall 49 of the cathode from the apertured end wall 52 of the grid cup. Electrical welds are then made to fix the cylindrical walls 62 and 64 of the rims 56 and 58 to the inside surface of the cylindrical wall 51 of the cathode cup 22.
  • the emissive coating 61 may include undesirable non-uniformities of thickness, such as peaks .70.
  • the peak 70 is spaced from the grid wall 52.
  • the fact that peripheral portions of the emissive end wall 40 are recessed from the grid wall 52 does not adversely affect the emission characteristics of the cathode or the electron beam formation by the grid. 7
  • a cathode sleeve with the emissive coating 61 not yet having been applied thereto is first formed to provide the domed end wall 40.
  • the emissive coating 61 is then applied to the convex surface of the domed Wall 46, such as by spraying, according to known practices.
  • the coated cathode sleeve36 is secured within the aperture of the ceramic disk 38 by forming the crimped beads 60 therein.
  • pair of retaining rims 56 and 58 are fitted to the ceramic disk 38 and the rims welded together.
  • the securing of the cathode and of the retaining rings to the ceramic washer may either precede or follow the cathode forming and coating steps.
  • the cathode assembly 35 may be mounted within the grid cup 22 either before or after the grid cup 22 is mounted on the insulator support rods 32 together with the other electrodes of the electron gun 18. According to a preferred practice, the cathode assembly 35 is mounted within the grid cup 22 after the grid cup has been mounted on the insulator support rods. In following such preferred practice, spacing of the emissive coating 61 from the grid aperture 54 is accomplished by the use of a capacitance measuring technique. In accordance with this technique, the cathode assembly 35 is telescopically slid into the grid cup 22 while a capacitance measurement is taken between the cathode and another of the electrodes, such as the control grid 22 or, preferably, the screen grid cup 24. When a predetermined capacitance corresponding to a desired cathode-grid spacing is obtained, the cathode assembly 35 is fixed relative to the grid cup 22 by welding the retaining rims 56 and 58 to the grid wall 51.
  • the prior art teaches pushing or bending, as by dimpling an emissive coated cathode end wall toward the apertured wall of a control grid cup.
  • dimpling is done as a final cathode positioning step for the purpose of obtaining the desired cathode-grid spac ing and is done after the emissive coating has been applied to the cathode sleeve.
  • This dimpling is so small as to provide an insignificant improvement in reduction of cathode-grid shorts or leakage as hereinbefore described.
  • a cathode ray tube having an electron gun including a close-spaced cathode grid assembly of the type comprising a centrally apertured control grid cup, a ceramic washer, a tubular cathode sleeve which has a domed end wall coated with electron emissive material by a process which often results in an irregular coating thickness that increases the likelihood of electrical cathode-grid leakage, said cathode being coaxially mounted within the aperture of said ceramic washer by circumferential crimped beads, and tubular retaining rim means coaxially surrounding said washer (e) coaxially sliding the assembly of said cathode, Washer, and retaining rim means into said grid cup to position the central portion of said emissive coating opposite the central aperture of said grid cup and within a few mils thereof so that the peripheral areas of said domed Wall are spaced farther from and fixed to said washer and to the internal surface of the side wall of said grid cup so as to support the central portion of said electron emissive coating co

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US227272A 1962-10-01 1962-10-01 Method of fabricating a cathode ray tube Expired - Lifetime US3192005A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL298574D NL298574A (en:Method) 1962-10-01
BE637906D BE637906A (en:Method) 1962-10-01
US227272A US3192005A (en) 1962-10-01 1962-10-01 Method of fabricating a cathode ray tube
GB36427/63A GB974557A (en) 1962-10-01 1963-09-16 Method of fabricating a cathode ray tube
DER36140A DE1237697B (de) 1962-10-01 1963-09-17 Verfahren zum Herstellung einer Kathoden-Steuerelektrodenanordnung fuer das Strahlerzeugersystem einer Kathodenstrahlroehre
FR949082A FR1371496A (fr) 1962-10-01 1963-09-30 Procédé de fabrication de tubes à rayons cathodiques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US227272A US3192005A (en) 1962-10-01 1962-10-01 Method of fabricating a cathode ray tube

Publications (1)

Publication Number Publication Date
US3192005A true US3192005A (en) 1965-06-29

Family

ID=22852462

Family Applications (1)

Application Number Title Priority Date Filing Date
US227272A Expired - Lifetime US3192005A (en) 1962-10-01 1962-10-01 Method of fabricating a cathode ray tube

Country Status (5)

Country Link
US (1) US3192005A (en:Method)
BE (1) BE637906A (en:Method)
DE (1) DE1237697B (en:Method)
GB (1) GB974557A (en:Method)
NL (1) NL298574A (en:Method)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2096415A (en) * 1933-12-27 1937-10-19 Bell Telephone Labor Inc Electron discharge device
US2967963A (en) * 1957-04-30 1961-01-10 Rca Corp Electron gun structure

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE740384C (de) * 1939-09-01 1943-10-19 Telefunken Gmbh Verfahren zum Einstellen des Abstandes zwischen der OEffnung der Steuerblende und der Stirnflaeche der Kathode einer Braunschen Roehre
DE884530C (de) * 1951-04-29 1953-07-27 Telefunken Gmbh Halterung fuer das Kathodenroehrchen von indirekt geheizten Hochvakuumroehren, insbesondere Kathodenstrahlroehren
DE879271C (de) * 1951-08-23 1953-06-11 Lorenz C Ag Verfahren zum Einstellen und Festlegen des Abstandes zwischen der Kathodenstirnflaeche und der Wehneltzylinderoeffnung einer Braunschen Roehre
DE921582C (de) * 1951-12-18 1954-12-20 Telefunken Gmbh Verfahren zur genauen Einstellung des Abstandes zwischen der OEffnung der Steuerblende und der Stirnflaeche der Kathode einer Braunschen Roehre

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2096415A (en) * 1933-12-27 1937-10-19 Bell Telephone Labor Inc Electron discharge device
US2967963A (en) * 1957-04-30 1961-01-10 Rca Corp Electron gun structure

Also Published As

Publication number Publication date
GB974557A (en) 1964-11-04
BE637906A (en:Method)
NL298574A (en:Method)
DE1237697B (de) 1967-03-30

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