US2827585A - Cathode-ray tube apparatus - Google Patents

Cathode-ray tube apparatus Download PDF

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Publication number
US2827585A
US2827585A US474126A US47412654A US2827585A US 2827585 A US2827585 A US 2827585A US 474126 A US474126 A US 474126A US 47412654 A US47412654 A US 47412654A US 2827585 A US2827585 A US 2827585A
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US
United States
Prior art keywords
anode
axis
cathode
tube
electrons
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Expired - Lifetime
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US474126A
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English (en)
Inventor
Niklas Wifrid Franz Kon Johann
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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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 cathode-ray apparatus. for reproducing images on a screen, which apparatus comprise an ion trap.
  • cathode-ray tubes for reproducing images on a screen, for example for oscillography or television, in which use is made of electromagnetic deflection means, that the electron gun, i. e. the assembly of electrodes producing a beam of electrons, should be of a design such that a separation can be made between the paths of electrons and the paths of negative ions which are unavoidably present in such tubes.
  • the electron gun i. e. the assembly of electrodes producing a beam of electrons
  • the electron gun i. e. the assembly of electrodes producing a beam of electrons
  • the negative ions which continue their path substantially linearly are collected.
  • the electrostatic field by which the electrons and the negative ions are jointly deflected may be obtained in that the anode and/ or the electrode of the electron gun preceding the anode is or are bevelled on the adjacent sides with respect to the axis of symmetry. Furthermore, it has been suggested that the anode and the preceding electrode, on their adjacent sides, should be cut off straightly with respect to the axis of the tube and that theaxes of the said electrodes should be arranged in parallel, but not in line with one another. In all these cases an inclined or tilted electrostatic field ensues by which the ions and the electrons are jointly deflected.
  • the present invention provides means which permit of substantially avoiding the said disadvantages by the use of an electron gun of a particular construction.
  • a cathode-ray tube for re- Patented Mar. 18, T1958 the tube.
  • the electron gun comprises at least a cathode, a control electrode, a tubular anode and at least one electrode located between the anode and the control electrode, the axis of the electron gun coinciding with the axis of the tube.
  • An ion trap action is produced by an electrostatic field between the anode andthe preceding electrode, which field is inclined with respect to the axis.
  • the characterizing feature of the invention is that on the side adjacent the cathode, through a length at least equal to the, diameter of the aperture of the anode on that side, the cross-sections of the anode with surfaces at right angles to the axis are asymmetric figures with respect to each line parallel to the intersecting line of the plane of the cross-sections and the plane passing through the axis and at right angles to the plane in which the ions are deflected, whereby the length inside the anode of the intersecting line of the last mentioned plane and the plane ofthe cross-section is divided by the point of intersection with the axis into two pieces of different length, of which the larger one is located on that side to which the ions are deflected,
  • the axis ofthe electron gun is to be understood to mean the perpendicular to the centre of the aperture of the control'electrodefor the passage of electrons.
  • the anode has the shape of a flattened cylinder.
  • the inclined electrostatic field extends in the anode at the most through a length equal to the diameter of the aperture of the anode on the side of the cathode, it is immaterial that the anode farther also has an asymmetric cross-section. However, for the sake of simplicity, the whole of the anode is frequently given a uniform cross-section.
  • the anode and/ or the electrode preceding the anode is cut off on the side of the anode along a plane inclined to the axis of the tube. An inclined electrostatic lens thus ensues between the anode and the preceding electrode, for example an accelerating anode.
  • the anode may beshaped in the form of an inclined cone.
  • Fig. 1 is a longitudinal section of a cathode-ray according to the invention.
  • Fig. 2 is a cross-section of the anode of the cathoderay tube of Fig. 1.
  • Fig. 3 is a cross-section of the anode of an electron gun which is a variant of the electron gun used in a tube as shown in Fig. 1.
  • Figs. 4 and 5 are longitudinal sections of other variants used in a tube as shown in Fig.1.
  • the cathode-ray tube comprises a neck 1 and an adjoining widerconical portion 2.
  • the conical portion contains a screen, 3, which is 'of luminescent material.
  • Numeral 4 indicates a focusing coil and 5 and 6 indicate a set of deflection coils.
  • the neck 1 of the tube contains the electron gun which in this case comprises a cathode 7, acontrol electrode 8, anaccelerating anode 9 and an anode 10.
  • the longitudinal axis of the cathode-ray tube which is at the same time the longitudinal axis of the electron gun, indicated by the line 11 11.
  • Both the anode 10 and the accelerating anode 9 are cut ofi obliquely with respect to the axis 11711, flius resulting in an inclined electrostatic field between the electrodes 9 and 10.
  • the beam of electrons and negative ions which is located in the axis in the electrode 9, is deflected by the inclined field as indicated by the dotted line. It is thus directed within the anode 10 to the wall at 12. Outside the cathode-ray tube there are arranged magnet poles 13 and 14 which exert a transverse force upon the beam directed to 12. This results into with tube - the anode is 13 mms.
  • the electrons are substantially not influenced, so that they are. collected by the wall at 12 and neutralised. If the anode would be circular-cylindrical in shape, the electrons could not be brought exactlyinto theaxis 11-11 by the single field provided by the magnet poles--13 and 14. They 'would then follow thefull line which is at an angle a with the axis. In the non-deflected position, the electrons would not strike the luminescence screen 3 at the point of intersection of this screen and the axis 1111,
  • ' comprises two circular-cylindrical parts 16 and 17 which are notco-axial with the neck of the tube.
  • Fig. 4 shows a part of another electron gun which permits of obtaining a similar effect as with the flattened cylinders shown in Figs. 1, 2 and 3.
  • the gun in this case comprises an inclined conical anode 18 of a shape such that the wall on the side of the impact point 19 of the ions is parallel to the axis 20 20.
  • the accelerating anode is indicated by 21.
  • the'anode comprises a circular-cylindrical part 23 and an inclined conical part 24.
  • the distance h is equal to the, diameter d of the aperture of the anode on the side of the cathode. As mentioned above, it may be larger,'but it must not be smaller.
  • d which is equal to the length h, is 7.2 mms.
  • the diameter of the cylindrical part of On the right side the length of this cylindricallpart is 19.5 mms. and on the left side 26 mms.
  • a neck portion having a longitudinal axis and an adjoining wider portion containing a screen luminescing upon electron bombardment, the center of said screen being aligned with the axis of the neck portion, an electron gun within said neck portion having a longitudinal axis coinciding with the axis of said neck portion and producing a combined beam of electrons and ions along the tube axis, said gun including a cathode, control electrode, additional electrode andanode arranged in that order, said anode and additional electrode producing an inclined electrostatic field causing the beam of electrons and ions to be bent away from the axis of the tube'toward one side of the anode, and means located substantially at the area of said bending and producing a single magnetic field to deflect back toward the axis only the electrons in said beam, whereby the ions are intercepted by the anode and whereby thedeflected-backelectron beam tends not to coincide with the tube -axis,'said anode having a shape whereby
  • Apparatus including a cathode-ray tube comprising a neck portion having a longitudinal axis and an adjoining wider portion containing a screen luminescing upon electron bombardment, the center of said screen being aligned with the axis of the neck portion, an electron gun within said neck portion having a longitudinal axis coinciding with theaxis of said neck portion and producing a combined beam of electrons and ions along the tube axis, said gun including a cathode, control electrode, additional electrode and anode arranged in that order, said anode and additional electrode producing an inclined electrostatic field causing the beam of electrons and ions side of the anode, and means located substantially at the to be bent away from the axis of the tube toward one area of said bending and producing a single magnetic field to deflect back toward the axis only the electrons in said beam, whereby the ions are intercepted by the anode and whereby the deflected-back electron beam tends not to :coincide with the tube axi
  • V 4 Apparatus as set forth in claimZ wherein the anode has an inclined, truncated, conical portion.

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  • Physical Vapour Deposition (AREA)
  • Electron Sources, Ion Sources (AREA)
US474126A 1953-12-15 1954-12-09 Cathode-ray tube apparatus Expired - Lifetime US2827585A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL325649X 1953-12-15

Publications (1)

Publication Number Publication Date
US2827585A true US2827585A (en) 1958-03-18

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Application Number Title Priority Date Filing Date
US474126A Expired - Lifetime US2827585A (en) 1953-12-15 1954-12-09 Cathode-ray tube apparatus

Country Status (7)

Country Link
US (1) US2827585A (de)
BE (1) BE534088A (de)
CH (1) CH325649A (de)
DE (1) DE1050455B (de)
FR (1) FR1115545A (de)
GB (1) GB768175A (de)
NL (1) NL183626B (de)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2412687A (en) * 1942-04-08 1946-12-17 Emi Ltd Electron lens
US2460609A (en) * 1946-01-24 1949-02-01 Rca Corp Beam aligning apparatus
US2515305A (en) * 1946-01-24 1950-07-18 Rca Corp Electromagnet
FR1043675A (fr) * 1951-10-09 1953-11-10 Radiotechnique Perfectionnement aux tubes à rayons cathodiques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2412687A (en) * 1942-04-08 1946-12-17 Emi Ltd Electron lens
US2460609A (en) * 1946-01-24 1949-02-01 Rca Corp Beam aligning apparatus
US2515305A (en) * 1946-01-24 1950-07-18 Rca Corp Electromagnet
FR1043675A (fr) * 1951-10-09 1953-11-10 Radiotechnique Perfectionnement aux tubes à rayons cathodiques

Also Published As

Publication number Publication date
DE1050455B (de) 1959-02-12
FR1115545A (fr) 1956-04-25
NL183626B (nl)
CH325649A (de) 1957-11-15
GB768175A (en) 1957-02-13
BE534088A (de)

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