US2723362A - Electron gun of the ion trap type - Google Patents

Electron gun of the ion trap type Download PDF

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Publication number
US2723362A
US2723362A US343195A US34319553A US2723362A US 2723362 A US2723362 A US 2723362A US 343195 A US343195 A US 343195A US 34319553 A US34319553 A US 34319553A US 2723362 A US2723362 A US 2723362A
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United States
Prior art keywords
pole pieces
electrons
magnetic
electrode
gun
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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
US343195A
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English (en)
Inventor
Gethmann Richard Barton
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.)
General Electric Co
Original Assignee
General Electric Co
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 NL87649D priority Critical patent/NL87649C/xx
Priority to BE527357D priority patent/BE527357A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US343195A priority patent/US2723362A/en
Priority to FR1104378D priority patent/FR1104378A/fr
Priority to GB7791/54A priority patent/GB747707A/en
Application granted granted Critical
Publication of US2723362A publication Critical patent/US2723362A/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
    • H01J29/84—Traps for removing or diverting unwanted particles, e.g. negative ions, fringing electrons; Arrangements for velocity or mass selection
    • H01J29/845—Traps for removing or diverting unwanted particles, e.g. negative ions, fringing electrons; Arrangements for velocity or mass selection by means of magnetic systems

Definitions

  • the present invention relates to an improved ion trap type electron gun, and particularly, to an improved mag netic deflecting structure therefor.
  • ions as well as electrons are present in the electric beam of high vacuum cathode ray tubes of the type commonly used in television receivers.
  • the presence of negative ions tends to result in screen burning, particularly in magnetic deflection type tubes, since in these tubes the ions are substantially undeflected and continuously impinge on a small area near the center of the tube.
  • Many television picture tubes have been manufactured which utilize the selective deflection of ions and electrons by a combination of electric and magnetic fields to collect the ions on a suitable part of the gun structure While allowing the electrons of the beam to travel on toward the screen of the tube.
  • I provide a magnetic deflection structure within the tube, and preferably forming a part of the gun structure, for giving a transverse deflection to the electrons, and particularly to function in combination with an opposed electrostatic field to provide an ion trap.
  • Fig. 2 is a sectional view taken along the line 2-2 0 Fig. 1.
  • a tetrode type of electron gun including a cathode sleeve 1 having on the end wall thereof an emissive coating 2 supported in insulated relation within a cupshaped control member or grid 3 having a beam passage 4 centrally located in the end wall thereof.
  • the gun includes an accelerating electrode or number two grid 5 and an anode 6.
  • a magnetic focusing assembly designated generally by the numeral 7 is supported on the outer end of the anode 6.
  • Said magnetic focusing structure is of the type described and claimed in my copending application Serial No. 274,785, filed March 4, 1952, and assigned to the assignee of this application and on which U. S. Patent No. 2,681,421 was granted June 15, 1954.
  • the focusing structure includes a pair of annular pole pieces 8 and 9 between which are supported a plurality of cylindrical permanent magnets 10 to produce a magneto motive force across a focusing or lens member 11 having a central passage therethrough.
  • the lens member ii is supported within a cylindrical member 12 forming an extension of the anode 6.
  • the various electrodes of the gun assembly are supported in the usual manner by means of studs 13 welded to the electrodes and embedded in a glass rod or stalk 14.
  • the focusing structure is in axial alignment with the neck of the cathode ray tube a portion of which is illustrated in the drawing at 15.
  • the anode 6 is maintained at the desired potential as a result of its connection with a conducting coating 16 on the wall of the tube.
  • the magnetic structure for effecting the transverse deflection of the electrons for ion trapping purposes is in the form of a sub-assembly which is supported within' the cylindrical anode electrode 6.
  • the sub-assembly includes a generally cup shaped member 18 having a wall portion 19 adjacent the open'end thereof conforming in size and shape to the interior of the anode cylinder 6.
  • the cup is drawn in somewhat near the closed end and shaped to position and support the magnetic field producing assembly including a pair of elongated pole pieces 20 and 21 as illustrated.
  • the cup is drawn in such a manner as to provide shoulders 22, 23, 24 and 25 which prevent the pole pieces from spreading outwardly.
  • a portion of the side wall of the cup 26 is struck inwardlly between the pole pieces at one end thereof to prevent the pole pieces from moving together.
  • the'pole pieces are held apart by a cylindrical permanent magnet 27 which provides the magneto motive force for the assembly.
  • the pole pieces are suitably recessed to receive the ends of the permanent magnet;
  • the assembly including the pole pieces 20 and 21 and the permanent magnet 27 are held in position and against the closed end of the cup by spot welding the ends of the pole piece to the flattened areas of the cupdesignated by the numeral 28.
  • the closed end of the cup is provided with a beam limiting aperture 29 which is centrally located in a direction transverse to the elongated pole -pieces 'but is substantially off center with respect to the anode sures the uniform spacing of the pole pieces 20 and 21 necessary to produce a uniform magnetic field.
  • the pole pieces 20 and 21 are also shaped to eliminate strong concentrations of the flux such as would occur at sharp edges.
  • the opposed surfaces are suitably curved and may be cylindrical surfaces.
  • the lower end of the anode cylinder 6 is provided with a diaphragm 3G having a beam aperture 31 formed therein and defined by a curved wall.
  • the closed end of the cup including the limiting aperture 29 is preferably positioned away from the diaphragm 30 by a distance at least equal to the diameter of the aperture 31 in order to insure that the beam limiting aperture 29 is in a substantially field free region.
  • the accelerating grid is operated at a voltage in the order of 400 volts and the final anode voltage is in the order of 12 to 16 kilovolts.
  • the composite beam having been deflected to the right moves substantially from the axis of the electrode 6 and passes through the limiting aperture 29 of the magnetic deflecting structure.
  • the strength of the magnetic field is just sufflcient to return the electrons to the axis of the focusing structure 7, the ions, being substantially undeflected, continue on and are collected on an interior surface of anode 6.
  • magnet 27 is magnetized to such a value that it is masked out by the focusing structure on opposite sides by adjusting the anode voltage to values which are equally above and below normal operating voltage. For example, if a tube has a normal anode voltage of 14,000 volts, the spot will be masked out on opposite sides of the center at anode voltages of 9,000 volts and 19,000 volts.
  • the focusing structure is on the axis of the tube envelope while the axis of the remainder of the gun structure extends to the left of the axis of the tube envelope.
  • the beam passes through the accelerating electrode 5 it is to the left of the axis of the envelope and the focusing structure.
  • it is deflected to the right in the region between the accelerating electrode 5 and the anode 6 it moves toward the axis of the tube envelope. It is possible under these circumstances for a single magnetic deflection to bend the beam of electrons just sufliciently to coincide with the axis of the tube envelope and the focusing structure.
  • An ion trap type of electron gun comprising means providing an electric beam having a given direction and including ions and electrons, means subjecting the beam to an electrostatic field transverse to said direction tending to deflect both said ions and electrons from said direction, and means within said gun including a permanent magnet and a pair of pole pieces subjecting said beam to a transverse magnetic field tending to deflect said electrons toward said original direction.
  • An electric discharge device comprising means providing an electric beam having a given direction and including ions and electrons, means subjecting the beam to an electrostatic field transverse to said direction tending to deflect both said ions and electrons from said direction, a cylindrical accelerating electrode in the path of said beam, and means including a permanent magnet and a pair of pole pieces within said electrode subjecting said beam to a transverse magnetic field tending to deflect said electrons toward said original direction.
  • An electric discharge device comprising means providing an electric beam having a given direction and including ions and electrons, a hollow cylindrical electrode in the path of said beam, and means including a permanent magnet and a pair of pole pieces within said electrode subjecting said beam to a transverse magnetic field.
  • An ion trap type of electron gun comprising means providing an electric beam having a given direction and including ions and electrons, a hollow cylindrical electrode in the path of said beam and a magnetic deflecting structure within said electrode including a pair of elongated pole pieces extending in generally parallel relation on opposite sides of the beam path and permanent magnet means extending between said pole pieces.
  • An ion trap type of electron gun comprising means providing an electric beam having a given direction and including ions and electrons, a hollow cylindrical electrode in the path of said beam and a magnetic deflecting structure within said electrode including a pair of elongated pole pieces extending in generally parallel relation on opposite sides of the beam path, said pole pieces having curved surfaces in the direction of beam travel and permanent magnet means extending between said pole pieces.
  • An electron gun comprising means providing an electron beam, a hollow cylindrical electrode in the path of said beam, a magnetic structure within said electrode for producing a transverse deflection of electrons within said electrode, and a magnetic focusing structure supported from the end of said electrode and having a focusing passage therethrough.
  • An electron gun comprising means providing an electron beam, a hollow cylindrical electrode in the path of said beam, a magnetic structure within said electrode for producing a transverse deflection of electrons within said electrode, and a magnetic focusing structure supported from the end of said electrode and having a focusing passage therethrough, the axis of said focusing structure extending at an angle to the axis of said electrode.
  • An ion trap type of electron gun comprising means producing an electric beam having a given direction and including ions and electrons, said gun including a pair of cylindrical electrodes supported in insulated relation and spaced in said direction, and said electrodes being shaped to deflect both said ions and said electrons transverse to said direction and a magnetic deflecting structure within one of said electrodes for deflecting the electrons of said beam in a direction opposite to the deflection produced by said electrodes, said structure including a cup-like cylindrical member having a limiting aperture in the closed end thereof, a permanent magnet extending transversely of the axis of said cup-like member and a pair of pole pieces extending from the ends of said magnet and positioned on opposite sides of said aperture, and a magnetic focusing structure supported on the end of said one electrode and having a passage therethrough at an angle to the axis of said one electrode.
  • An ion trap type of electron gun comprising means producing an electric beam having a given direction and including ions and electrons, said gun including a pair of cylindrical electrodes supported in insulated relation and spaced in said direction, a magnetic deflecting structure within one of said electrodes for deflecting the electrons of said beam transversely with respect to the beam path, said structure including a transverse member having a limiting aperture therein, a permanent magnet extending transversely of the axis of said one electrode, a pair of pole pieces extending from the ends of said magnet and positioned on opposite sides of said aperture, and an apertured member at the end of said electrode to provide a substantially field-free region at said limiting aperture.
  • An ion trap type of electron gun comprising means producing an electric beam having a given direction and including ions and electrons, said gun including a pair of cylindrical electrodes supported in insulated relation and spaced in said direction, a magnetic deflecting structure within one of said electrodes for deflecting the electrons of said beam transversely with respect to the beam path, said structure including a transverse member having a limiting aperture therein, a permanent magnet extending transversely of the axis of said one electrode, and a pair of pole pieces extending from the ends of said magnet and positioned on opposite sides of said aperture.
  • a magnetic deflecting structure comprising a cuplike sheet metal member of non-magnetic material having an aperture in the end wall thereof, a pair of elongated pole pieces extending transversely within said cup on opposite sides of said aperture, a permanent magnet extending between said pole pieces near one end thereof,
  • said cup being shaped to provide shoulders engaging the outer surfaces of said pole pieces at the ends thereof and flattened surfaces engaging the ends of said pole pieces to facilitate Welding of said pole pieces to said cup.
  • a magnetic deflecting structure comprising a cuplike sheet metal member of non-magnetic material having an aperture in the end wall thereof, a pair of elongated pole pieces extending transversely within said cup on opposite sides of said aperture, a permanent magnet extending between said pole pieces near one end thereof and having the ends thereof received in recesses formed in said pole pieces.
  • a magnetic beam deflecting structure comprising a cup-like sheet metal member having an aperture in the end wall thereof, a pair of elongated pole pieces extending transversely within said cup on opposite sides of said aperture, and a permanent magnet extending between said pole pieces near one end thereof.
  • An electric discharge device comprising means providing an electric beam having a given direction and including ions and electrons, a hollow cylindrical electrode in the path of said beam and means including a permanent magnet and a pair of pole pieces supported from said electrode subjecting said beam to a transverse magnetic field.
  • An electric discharge device comprising means providing an electric beam having a given direction and including ions and electrons, a hollow cylindrical electrode having a beam passage therethrough and means supported from said electrode subjecting said beam to a transverse magnetic field including a permanent magnet and a pair of pole pieces, said pole pieces extending on opposite sides of said beam passage.
  • An electric discharge device comprising means providing an electric beam having a given direction and including ions and electrons, a hollow cylindrical electrode having a beam passage therethrough and means supported from said electrode subjecting said beam to a transverse magnetic field including a permanent magnet and a pair of elongated pole pieces, said pole pieces extending on opposite sides of said beam passage and having the opposed faces thereof curved about axes parallel to the length of said pole pieces.

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US343195A 1953-03-18 1953-03-18 Electron gun of the ion trap type Expired - Lifetime US2723362A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL87649D NL87649C (fr) 1953-03-18
BE527357D BE527357A (fr) 1953-03-18
US343195A US2723362A (en) 1953-03-18 1953-03-18 Electron gun of the ion trap type
FR1104378D FR1104378A (fr) 1953-03-18 1954-03-16 Perfectionnements aux canons électroniques
GB7791/54A GB747707A (en) 1953-03-18 1954-03-17 Improvements relating to electron guns

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US343195A US2723362A (en) 1953-03-18 1953-03-18 Electron gun of the ion trap type

Publications (1)

Publication Number Publication Date
US2723362A true US2723362A (en) 1955-11-08

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US343195A Expired - Lifetime US2723362A (en) 1953-03-18 1953-03-18 Electron gun of the ion trap type

Country Status (5)

Country Link
US (1) US2723362A (fr)
BE (1) BE527357A (fr)
FR (1) FR1104378A (fr)
GB (1) GB747707A (fr)
NL (1) NL87649C (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2921212A (en) * 1953-05-30 1960-01-12 Int Standard Electric Corp Gun system comprising an ion trap
US2964880A (en) * 1956-05-25 1960-12-20 Fivre Valvole Radio Elett Spa Process for preparing glass elements
US3027479A (en) * 1958-06-27 1962-03-27 Rca Corp Electron guns
US3119988A (en) * 1955-12-01 1964-01-28 Leonard D Barry Magnetic recorder for symbols

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2188579A (en) * 1933-05-27 1940-01-30 Loewe Radio Inc Cathode ray tube, more particularly for television purposes
US2305761A (en) * 1938-03-08 1942-12-22 Bodo V Borries Electron-optical lens
US2496127A (en) * 1947-02-05 1950-01-31 Rca Corp Electron gun for cathode-ray tubes
US2515305A (en) * 1946-01-24 1950-07-18 Rca Corp Electromagnet
US2619607A (en) * 1951-03-10 1952-11-25 Glaser Steers Corp Internal focusing device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2188579A (en) * 1933-05-27 1940-01-30 Loewe Radio Inc Cathode ray tube, more particularly for television purposes
US2305761A (en) * 1938-03-08 1942-12-22 Bodo V Borries Electron-optical lens
US2515305A (en) * 1946-01-24 1950-07-18 Rca Corp Electromagnet
US2496127A (en) * 1947-02-05 1950-01-31 Rca Corp Electron gun for cathode-ray tubes
US2619607A (en) * 1951-03-10 1952-11-25 Glaser Steers Corp Internal focusing device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2921212A (en) * 1953-05-30 1960-01-12 Int Standard Electric Corp Gun system comprising an ion trap
US3119988A (en) * 1955-12-01 1964-01-28 Leonard D Barry Magnetic recorder for symbols
US2964880A (en) * 1956-05-25 1960-12-20 Fivre Valvole Radio Elett Spa Process for preparing glass elements
US3027479A (en) * 1958-06-27 1962-03-27 Rca Corp Electron guns

Also Published As

Publication number Publication date
BE527357A (fr)
GB747707A (en) 1956-04-11
NL87649C (fr)
FR1104378A (fr) 1955-11-18

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