US2845563A - Beam generating system - Google Patents

Beam generating system Download PDF

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Publication number
US2845563A
US2845563A US390328A US39032853A US2845563A US 2845563 A US2845563 A US 2845563A US 390328 A US390328 A US 390328A US 39032853 A US39032853 A US 39032853A US 2845563 A US2845563 A US 2845563A
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United States
Prior art keywords
aperture
electrode
anode
generating system
beam generating
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Expired - Lifetime
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US390328A
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English (en)
Inventor
Berthold Wolfgang
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International Standard Electric Corp
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International Standard Electric Corp
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Filing date
Publication date
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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

  • This invention relates to systems for generating electron beams for cathode ray tubes and particularly those tubes using magnetic deflection. It is a well-known fact that when scanning the picture screen of cathode ray tubes, only the electrons are deflected by means of variable magnetic fields, while the negative ions, on account of their greater mass, meet on the center of the fluorescent screen.
  • the electrons and negative ions are first bent away from the axis of the system by a transverse electric field.
  • An adjustable magnet external of the tube directs the electrons back to the axis so that they can reach the oscilloscope screen through the lens apertures of the system, whereas the ions owing to their greater mass are not bent back by the magnet and are collected out-side the axis.
  • the transverse electric field was generated in various ways. For example, it can be produced by a condenser field.
  • the electric field is generated through a slanting lens between two electrodes of the beam generating system.
  • the entire electron gun is slanted away from the desired direction and the electrons of the resultant beam are then returned in the desired direction by the use of a magnet.
  • the anode cylinder with its central aperture is so displaced with respect to the rest of the system that the ions will impinge upon the walls of the anode cylinder whereas the electrons are deflected back magnetically in the desired direction.
  • the condenser arrangement requires additional electrodes; the slanted lens system-s result in an elliptical cross section of the beam and the slanted sys-' tern arrangement or displaced anode cylinder are diflicult to manufacture and entail additional expense for the ad- 7 justment thereof.
  • the foregoing drawbacks are avoided by supplying one electrode of the beam generating system with an asymmetrical aperture.
  • the entire system is conventional except for the fact that one aperture is olf center and does not coincide with the axis of the cylinder. Since the aperture is in the acceleration path of the electrons, it will so remodulate the field lines that the beam of electrons and ions is deflected away from the cylinder axis. The electrons are then directed back magnetically in known manner whereas ions are cap- "ture'cl'by a suitable collector.
  • Fig. l is a schematic diagram of a tetrode electron gun system and Fig. 2 is a view of the apertures taking the line A-A of Fig. 1.
  • Fig. 3 is a diagram showing the lens of Fig. l arranged in a cathode ray tube envelope
  • Fig. 4 is a diagrammatic illustration of a suitable ion trap magnet.
  • the electron gun has a cathode 1 Within a control electrode cylinder '2 having an aperture through which the beam passes into an accelerating electrode 3, the open end of which leads into an anode cylinder 4.
  • the electron and ion beam indicated by the numeral 5 is bent due to the asymmetric anode aperture 6.
  • the asymmetry of the arrangement of the aperture is shown more clearly in Fig. 2 where 7 designates the axis of the anode cylinder 4, and 8 designates the center of the aperture opening 6.
  • FIG. 3 the electron gun is shown diagrammatically in a single line drawing of a cathode ray tube.
  • the electron beam Se is' shown in its corrected position after being redirected 'by means of the magnetic field G shown diagrammatically by the shading in this figure.
  • the ions from the beam however follow the curve 5i and are intercepted by aperture plate 11 so that they will not impinge on the cathode ray screen.
  • a suitable form of ion trap magnet for producing field G is shown in Fig. 4. This may be of the present commercial type consisting of a permanent magnet 12 and two .pole shoes 10 suitably shaped to fit around the neck of the cathode ray tube.
  • a beam generating system for a cathode ray tube consisting essentially of a cathode electrode, a control electrode adjacent said cathode electrode, a first accelerating electrode adjacent said control electrode and an anode electrode, said control, accelerating and anode electrodes being mounted serially along a given longitudinal axis and symmetrically disposed thereabout and with respect thereto, said control electrode and accelerating electrode each having an aperture concentric with said longitudinal axis, through which the beam passes, said anode electrode having an aperture eccentric with respect tosaid axis positioned at the end of said anode electrode facing said cathode to produce with the accelerating electrode an electrostatic field deflecting the beam transversely.
  • a beam generating system according to claim 1, References Cited in the file of this patent wherein said accelerating and anode electrode have the UNITED STATES PATENTS same diameter and wherein one portion of the circumference of the anode aperture is aligned t n Pop 2,146,366 Batchelqr Feb. 7, 1939 tion of the accelerating electrode peri hery while the 2,472,766 W H g June 7, 1949 r st of the anode aperture fall within and i spaced 2,515,305 f July 18, 1950 from t pe imeter of the circle formed by the projecgigs; 2 g, t'
  • a beam generating system whereln the dlstance between the centers of the two aper- 0 FOREIGN PATENTS tures lies between /2 and of the diameter of the anode aperture. 1,043,675 France June 17, 1953

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  • Electron Sources, Ion Sources (AREA)
US390328A 1952-11-07 1953-11-05 Beam generating system Expired - Lifetime US2845563A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2845563X 1952-11-07

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US2845563A true US2845563A (en) 1958-07-29

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US390328A Expired - Lifetime US2845563A (en) 1952-11-07 1953-11-05 Beam generating system

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US (1) US2845563A (en))
BE (1) BE526614A (en))
NL (1) NL182593B (en))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3045141A (en) * 1957-04-15 1962-07-17 Rca Corp Electron beam tube

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2146366A (en) * 1935-04-23 1939-02-07 John C Batchelor Electronic apparatus
US2472766A (en) * 1944-12-28 1949-06-07 Cossor Ltd A C Cathode-ray tube
US2515305A (en) * 1946-01-24 1950-07-18 Rca Corp Electromagnet
US2579351A (en) * 1949-08-30 1951-12-18 Rca Corp Isocon pickup tube
US2604599A (en) * 1949-09-17 1952-07-22 Sylvania Electric Prod Cathode-ray tube
US2617060A (en) * 1950-05-02 1952-11-04 Hartford Nat Bank & Trust Co Cathode-ray tube
FR1043675A (fr) * 1951-10-09 1953-11-10 Radiotechnique Perfectionnement aux tubes à rayons cathodiques

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2146366A (en) * 1935-04-23 1939-02-07 John C Batchelor Electronic apparatus
US2472766A (en) * 1944-12-28 1949-06-07 Cossor Ltd A C Cathode-ray tube
US2515305A (en) * 1946-01-24 1950-07-18 Rca Corp Electromagnet
US2579351A (en) * 1949-08-30 1951-12-18 Rca Corp Isocon pickup tube
US2604599A (en) * 1949-09-17 1952-07-22 Sylvania Electric Prod Cathode-ray tube
US2617060A (en) * 1950-05-02 1952-11-04 Hartford Nat Bank & Trust Co Cathode-ray tube
FR1043675A (fr) * 1951-10-09 1953-11-10 Radiotechnique Perfectionnement aux tubes à rayons cathodiques

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3045141A (en) * 1957-04-15 1962-07-17 Rca Corp Electron beam tube

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BE526614A (en))
NL182593B (nl)

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