US3145318A - Cathode grid assembly for electron gun - Google Patents

Cathode grid assembly for electron gun Download PDF

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Publication number
US3145318A
US3145318A US68977A US6897760A US3145318A US 3145318 A US3145318 A US 3145318A US 68977 A US68977 A US 68977A US 6897760 A US6897760 A US 6897760A US 3145318 A US3145318 A US 3145318A
Authority
US
United States
Prior art keywords
cathode
shield
tubular
grid
electron gun
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
US68977A
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English (en)
Inventor
Raymond C Paull
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 NL271321D priority Critical patent/NL271321A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US68977A priority patent/US3145318A/en
Priority to GB34612/61A priority patent/GB975023A/en
Priority to FR878176A priority patent/FR1305069A/fr
Priority to DER31443A priority patent/DE1214796B/de
Priority to BE610243A priority patent/BE610243A/fr
Application granted granted Critical
Publication of US3145318A publication Critical patent/US3145318A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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

Definitions

  • One type of electron gun commonly used in cathode ray tubes comprises a plurality of coaxial electrodes mounted in spaced relationship along a plurality of insulator support rods.
  • the electrodes usually include a centrally apertured tubular control grid cup and a tubular cathode having one end closed and coated with electron emissive material and coaxially mounted within the grid cup.
  • the cathode is mounted within a central aperture of a supporting ceramic washer by crimped circumferential beads in the cathode which bear against the opposite fiat faces
  • the ceramic washer is in turn coaxially mounted Within the grid cup by retainer rings welded to the inner cylindrical wall of the grid cup. The cathodeis thus coaxially secured within the grid cup with its emissive coating adjacent the central aperture of the grid cup.
  • a ceramic washer which is costly, has the added disadvantage of providing a relatively massive part which acts as a temporary heat sink. This latter characteristic causes the ceramic washer to temporarily absorb heat from the cathode until the ceramic ⁇ washer reaches a certain equilibrium temperature.
  • Another object of my invention is the provision of a new and improved cathode-control grid assembly which prevents the formation of harmful electrical leakage paths caused by sublimation of cathode material.
  • a tubular cathode having an end wall coated with electron emissive material is supported coaxially within a tubular cathode shield by a cathode support ring between the cathode and the shield.
  • the shield is, in turn, mounted on an insulator support rod.
  • a tubular centrally apertured control grid cup is coaxially telescoped over the shield and the emissive end of the cathode to an extent suiiicient to substantially conceal the external surface of the cathode.
  • the control grid is mounted on the insulator support rods independently of the cathode.
  • FIG. 1 is a longitudinal section of portions of a cathode ray tube containing an electron gun according to this invention.
  • FIG. 2 is an enlarged longitudinal section of the cathode-control grid assembly of the electron gun of FIG. 1.
  • FIG. 1 shows an electron gun 6 disposed within a neck 8 of a cathode ray tube envelope.
  • the gun 6 and neck 8 may, for example, form a portion of a cathode ray tube which includes an envelope funnel section 10 attached to the neck 8, a faceplate 12 closing the large end of the funnel remote from the neck 8, and a phosphor screen 13 on the internal surface of the faceplate.
  • the neck 3 is closed at one end by a stem 14 which includes a pinrality of stiff lead-ins 15 sealed therethrough for supplying suitable potentials to the electrodes of the gun 6.
  • the electron gun 6 comprises a plurality of circularly symmetrical, for example tubular, electrodes mounted in coaxial spaced relationship along a plurality of glass insulator support rods 16.
  • the electrodes include a cathode structure 17, control 'grid 18, screen grid 21), a first lens electrode 22, a focus electrode 24, and a second lens elec- Each of these electrodes is independently mounted on the glass rods 16 by pairs of U shaped elecwelded to their respective electrodes and embedded in the glass rods 16.
  • a coiled heater 33 is disposed within the cathode and is supported on a pair of straps 34 which are likewise embedded in the glass rods 16.
  • FIG. 2 illustrates in greater detail the cathode and control grid assembly of the electron gun 6 of FIG. 1, which assembly is made in accordance with this invention.
  • control grid 18 comprises a tubular cup-like electrode having an end wall 4% with a small central aperture 42 to the bights of the pair of electrode mounting elements 28, the ends of which are embedded in the glass support rods 16.
  • the cathode structure 17 comprises a tubular cathode 46 closed at one end with a transverse wall 48 which is coated on the external surface with electron emissive material 59.
  • the tubular cathode 46 is disposed coaxially within a tubular cathode shield 52 which includes an outwardly extending radial flange 54 at the end thereof remote from the emissive end of the cathode 46.
  • the cathode 46 is supported within the cathode shield 52 by a cathode support ring 56 fixed therebetween.
  • the support ring 56 includes an inner cylindrical portion 53 welded to the external cylindrical surface of the cathode 46 at its end opposite the emissive end thereof, and an outer cylindrical section 60 welded to the inner cylindrical surface of the cathode shield 52. As shown in the drawing, the cathode support ring 56 may be welded to the shield 52 adjacent its flanged end.
  • the cathode shield 52 and the cathode 46 are mounted on the glass support rods 16 independently of the control grid 18 by the pair of U-shaped electrode mounting elements 27, the bights of which are Welded to the shield 52 and the ends of which are embedded in the glass rods 16.
  • the cathode 46 and cathode shield 52 are disposed coaxially within the control grid cup 18 with the emissive end 50 of the cathode adjacent the central aperture 42 of the grid cup 18.
  • the tubular wall 44 of the grid cup 18 extends back along the cathode 46 and shield 52 to adjacent the electrode mounting elements 27 which support the cathode and shield.
  • the amount of longitudinal overlap of the tubular wall 44 of the grid cup and the cathode shield 52 is such that the external tubular surface of the cathode 46 is substantially concealed from along line-of-sight paths extending out of the open end of the grid cup 18.
  • the shield 52 extends sufllciently into the grid cup 18 that it intersects a straight line from the edge 62 of the closed end of the cathode 45 to the edge 64 of the open end of the grid cup 18.
  • cathode-control grid assembly good heat isolation of the cathode is provided by making the cathode support ring 56 of thin metal. Moreover, the cathode shield 52 is provided with an internal surface of high heat reflectivity. Thus, heat dissipation by radiation from the cathode is minimized, increasing cathode heating efliciency.
  • electrical connection may be provided to the cathode by afixing one of the lead-ins to one of the electrode mounting elements 27.
  • connection tab fixed directly to the cathode 46 is avoided, and consequently, possible excessive heat loss from the cathode to the tab is avoided.
  • the structure of the present invention also facilitates the use of electrical measuring techniques for adjusting the cathode-to-control grid spacing.
  • the structure of FIG. 2 can be fabricated by first fixing the cathode 46 to the cathode support ring 56 separately from the cathode shield 52, and mounting the control grid 18 and the cathode shield 52 on the glass support rods 16. Thecathode 46, together with its support ring 56, may then be tclescoped within the cathode shield 52.
  • the cathode support ring 56 is welded to the cathode shield 52.
  • electrical measurement of the spacing between the cathode 46 and the grid cup 18 may be by a capacitance bridge technique wherein the capacity between the cathode 46 and either the screen grid 20 or the control grid 18 is measured.
  • An electron gun comprising an insulator support rod, a tubular cathode, a tubular cathode shield coaxially surrounding said cathode, a cathode support ring concentrically fixed between said shield and one end of said cathode, mounting means fixed to said insulator rod and to the end of said shield adjacent said one end of said cathode for supporting said cathode and said shield relative to said rod, a control grid cup disposed coaxially with said cathode and shield with the other ends of said cathode and shield extending thereinto, and mounting means fixed to said grid cup and said insulator rod for supporting said grid cup relative to but independently of said cathode and said shield.
  • An electron gun comprising an insulator support rod, a tubular cathode, a tubular cathode shield coaxilly surrounding said cathode, a cathode support ring concentrically fixed between adjacent ends of said cathode and said shield, mounting means fixed to said adjacent end of said shield and to said insulator rod for supporting said cathode and said shield relative to said rod, a control grid cup disposed coaxially with said cathode and shield with the other ends of said cathode and shield extending thereinto a distance suflicient to substantially conceal the external surface of said cathode, and mounting means fixed to said grid cup and to said insulator rod for supporting said grid cup relative to but independently of said cathode and said shield, said cathode, support ring, shield, and grid cup being so disposed that said cathode is axially slidable relative to said grid cup prior to said support ring being fixed to both said cathode and said shield.
  • an electron gun comprising a plurality of circularly symmetric electrodes in coaxial spaced relation, a glass rod on which said electrodes are mounted, a tubular cathode having an end wall coated with electron emissive material, a tubular cathode shield into which said cathode is coaxially disposed, the coated end of said cathode extending beyond the adjacent end of said shield, a cathode support ring concentrically fixed to the other end of said cathode and to said shield to support said cathode from said shield, first electrode mounting means embedded in said glass rod and fixed to said shield adjacent its end opposite the end thereof adjacent the coated end of said cathode, a control grid cup having an apertured end wall and a tubular wall telescoped over the coated end of said cathode and the end of said shield adjacent thereto, the tubular Wall of said grid cup extending part way back said shield to adjacent said first electrode mounting means, and second electrode mount ing means embedded in said glass rod and fixed to the tubular wall of said grid cup
  • An electron gun cathode-control grid assembly comprising a glass support rod, a control grid cup having a tubular Wall and a centrally apertured end wall, electrode mounting means welded to said tubular wall and embedded in said glass rod to support said grid cup relative to said glass rod, a tubular cathode having at one end a closure wall coated with electron emissive material, a tubular cathode shield into which said cathode is telescoped, the coated end of said cathode being disposed outside of said shield beyond the adjacent end thereof, a cathode support ring concentric with said cathode and said shield and having an inner cylindrical section fixed to the outer cylindrical surface of said cathode at the other end thereof and an outer cylindrical section fixed to the inner cylindrical surface of said shield to support said cathode and said shield relative to each other, said cathode and shield being coaxial with said grid cup with the coated end of said cathode and said shield extending thereinto a distance suflicient to substantially conceal the external tubular surface of

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  • Electrodes For Cathode-Ray Tubes (AREA)
US68977A 1960-11-14 1960-11-14 Cathode grid assembly for electron gun Expired - Lifetime US3145318A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL271321D NL271321A (de) 1960-11-14
US68977A US3145318A (en) 1960-11-14 1960-11-14 Cathode grid assembly for electron gun
GB34612/61A GB975023A (en) 1960-11-14 1961-09-27 Cathode grid assembly for electron gun
FR878176A FR1305069A (fr) 1960-11-14 1961-11-07 Canon à électrons pour tubes cathodiques
DER31443A DE1214796B (de) 1960-11-14 1961-11-11 Kathodenstrahlerzeugungssystem und Verfahren zum Zusammenbau des Strahlerzeugungssystems
BE610243A BE610243A (fr) 1960-11-14 1961-11-13 Ensemble cathode-grille pour canon électronique.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US68977A US3145318A (en) 1960-11-14 1960-11-14 Cathode grid assembly for electron gun

Publications (1)

Publication Number Publication Date
US3145318A true US3145318A (en) 1964-08-18

Family

ID=22085913

Family Applications (1)

Application Number Title Priority Date Filing Date
US68977A Expired - Lifetime US3145318A (en) 1960-11-14 1960-11-14 Cathode grid assembly for electron gun

Country Status (5)

Country Link
US (1) US3145318A (de)
BE (1) BE610243A (de)
DE (1) DE1214796B (de)
GB (1) GB975023A (de)
NL (1) NL271321A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3254251A (en) * 1962-07-06 1966-05-31 Rca Corp Cathode ray tube gun having nested electrode assembly
US3333138A (en) * 1965-01-11 1967-07-25 Rauland Corp Support assembly for a low-wattage cathode
US4514660A (en) * 1983-11-29 1985-04-30 Rca Corporation Cathode-ray tube having an electron gun assembly with a bimetal cathode eyelet structure
US4554480A (en) * 1983-11-29 1985-11-19 Rca Corporation Cathode-ray tube having an electron gun assembly with emissivity modifying means
US4559468A (en) * 1982-06-25 1985-12-17 Raytheon Company Cathode ray tube gun support

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2081942A (en) * 1933-06-16 1937-06-01 Harry R Lubcke Cathode ray tube
US2383751A (en) * 1942-05-07 1945-08-28 Int Standard Electric Corp Electron lens
US2510267A (en) * 1946-10-30 1950-06-06 Rca Corp Grid cathode assembly for cathoderay tubes
US2914694A (en) * 1957-10-04 1959-11-24 Rca Corp Cathode assembly
GB827557A (en) * 1957-07-29 1960-02-10 Pye Ltd Improvements in or relating to cathodes for electron guns of cathode ray tubes

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1005201B (de) * 1953-05-06 1957-03-28 Telefunken Gmbh Halterung fuer die indirekt geheizte Kathode einer elektrischen Entladungsroehre, insbesondere einer Elektronenstrahlroehre
DE1738685U (de) * 1956-11-21 1957-01-31 Gen Electric Halterung fuer die indirekt geheizte kathode einer elektrischen entladungsroehre, insbesondere einer elektronenstrahlroehre.

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2081942A (en) * 1933-06-16 1937-06-01 Harry R Lubcke Cathode ray tube
US2383751A (en) * 1942-05-07 1945-08-28 Int Standard Electric Corp Electron lens
US2510267A (en) * 1946-10-30 1950-06-06 Rca Corp Grid cathode assembly for cathoderay tubes
GB827557A (en) * 1957-07-29 1960-02-10 Pye Ltd Improvements in or relating to cathodes for electron guns of cathode ray tubes
US2914694A (en) * 1957-10-04 1959-11-24 Rca Corp Cathode assembly

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3254251A (en) * 1962-07-06 1966-05-31 Rca Corp Cathode ray tube gun having nested electrode assembly
US3333138A (en) * 1965-01-11 1967-07-25 Rauland Corp Support assembly for a low-wattage cathode
US4559468A (en) * 1982-06-25 1985-12-17 Raytheon Company Cathode ray tube gun support
US4514660A (en) * 1983-11-29 1985-04-30 Rca Corporation Cathode-ray tube having an electron gun assembly with a bimetal cathode eyelet structure
US4554480A (en) * 1983-11-29 1985-11-19 Rca Corporation Cathode-ray tube having an electron gun assembly with emissivity modifying means

Also Published As

Publication number Publication date
NL271321A (de)
DE1214796B (de) 1966-04-21
GB975023A (en) 1964-11-11
BE610243A (fr) 1962-03-01

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