EP0214816A2 - Tubes à rayons cathodiques - Google Patents

Tubes à rayons cathodiques Download PDF

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Publication number
EP0214816A2
EP0214816A2 EP86306667A EP86306667A EP0214816A2 EP 0214816 A2 EP0214816 A2 EP 0214816A2 EP 86306667 A EP86306667 A EP 86306667A EP 86306667 A EP86306667 A EP 86306667A EP 0214816 A2 EP0214816 A2 EP 0214816A2
Authority
EP
European Patent Office
Prior art keywords
limiting aperture
electrode
cathode ray
ray tube
voltage
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.)
Withdrawn
Application number
EP86306667A
Other languages
German (de)
English (en)
Other versions
EP0214816A3 (fr
Inventor
Takehiro C/O Patent Division Kakizaki
Koumei C/O Patent Division Kusuda
Koichi C/O Patent Division Furui
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.)
Sony Corp
Original Assignee
Sony 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
Application filed by Sony Corp filed Critical Sony Corp
Publication of EP0214816A2 publication Critical patent/EP0214816A2/fr
Publication of EP0214816A3 publication Critical patent/EP0214816A3/fr
Withdrawn legal-status Critical Current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
    • 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
    • H01J29/488—Schematic arrangements of the electrodes for beam forming; Place and form of the elecrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J3/00—Details of electron-optical or ion-optical arrangements common to two or more basic types of discharge tubes or lamps
    • H01J3/02—Electron guns
    • H01J3/029—Schematic arrangements for beam forming

Definitions

  • This invention relates to cathode ray tubes including an electron gun with a limiting aperture.
  • a high definition picture tube or a beam index type colour picture tube it is necessary for the electron beam spot diameter on the fluorescent screen to be small, so as to obtain a good picture image.
  • the primary ways of obtaining a small beam spot diameter are to reduce the diameter of a cross-over point which forms the object point to be projected, or to reduce the aberration of a projection lens.
  • a limiting aperture be provided in an electron gun.
  • Figure 6 of the accompanying drawings shows a typical arrangement of the limiting aperture.
  • the cathode ray tube includes a cathode K, first and second grid electrodes Gl and G2, third and fourth grid electrodes G3 and G4 forming a focusing electrode, and a fluorescent screen 1.
  • a limiting aperture LA is arranged at the rear stage of the electrode G2.
  • the apparent diameter of the cross-over point may be reduced, and the divergence angle of the electron beam may be reduced (which is equivalent to enlargement of a lens diameter).
  • the beam spot diameter may be made small.
  • a limiting aperture LA is usually adopted in a pick-up tube.
  • a serious problem arises. Namely, when the electron beam strikes the limiting aperture LA, a large number of secondary electrons e' are generated.
  • the voltage on the target screen is low, and accordingly the secondary electrons e' do not land on the target screen.
  • the voltage on the fluorescent screen 1 is high, and accordingly the second electrons e' land on the fluorescent screen 1 as shown in Figure 6.
  • a cathode ray tube including an electron gun with a limiting aperture; characterized in that:
  • the secondary electrons generated from the limiting aperture are hindered from reaching the fluorescent screen or the target screen. Accordingly, the halo phenomenon due to the secondary electrons may be prevented.
  • a disc-like secondary electron control electrode SG between the limiting aperture LA and the electrode G3.
  • the potential on the axis in the vicinity of the control electrode SG, for example, at a centre point P of an aperture of the electrode SG, is lower than that of the limiting aperture LA by several tens of volts, for example, 50 V or more, and the voltage is applied to the control electrode SG.
  • the voltage of the control electrode SG becomes 0 to 300 V.
  • the range of voltages results from differences in the axial potential in the vicinity of the control electrode SG, dependent upon the position of the control electrode SG and the diameter of the aperture of the control electrode SG.
  • Figure 2 is a schematic graph showing distribution of the axial potential
  • Figure 3 shows part of the structure of the embodiment of Figure 1.
  • the aperture diameter ⁇ 1 of the electrode Gl is 0.2 mm; the aperture diameter ⁇ 2 of the electrode G2 is 0.25 mm; the diameter of the limiting aperture LA is 0.1 mm; the aperture diameter ⁇ 5 G of the control electrode SG is 1.5 mm; the distance d (K - Gl) between the cathode K and the electrode Gl is 0.1 mm; the distance d (G1 - G2) between the electrodes Gl and G2 is 0.25 mm; the distance d (G2 - LA) between the electrode G2 and the limiting aperture LA is 0.55 mm; the distance d (LA - SG) between the limiting aperture LA and the control electrode SG is 0.2 mm; and the distance d (SG - G3) between the control electrode SG and the electrode G3 is 0.2 mm.
  • the voltage EK of the cathode K is 0 V; the voltage EG1 of the electrode Gl is -25 V; the voltage EG2 of the electrode G2 is 550 V; the voltage ELA of the limiting aperture LA is 550 V; the voltage ESG of the control electrode SG is 0 V; and the voltage EG3 of the electrode G3 is 1.6 kV.
  • the halo phenomenon due to the secondary electrons e' may be prevented. Therefore, the beam spot diameter on the fluorescent screen 1 may be made small.
  • FIGS 4 and 5 show modified embodiments of the present invention.
  • the second electron control electrode SG is cylindrical, and the other members are constituted in the same manner as in Figure 1 to show the same operation and effect.
  • the secondary electron control electrode SG is not specifically provided, but the voltage of the electrode G3 is appropriately selected to obtain the same operation and effect.
  • the voltages of the components may be as follows:

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Discharge Lamps And Accessories Thereof (AREA)
EP86306667A 1985-08-29 1986-08-28 Tubes à rayons cathodiques Withdrawn EP0214816A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP60190434A JPS6251137A (ja) 1985-08-29 1985-08-29 陰極線管
JP190434/85 1985-08-29

Publications (2)

Publication Number Publication Date
EP0214816A2 true EP0214816A2 (fr) 1987-03-18
EP0214816A3 EP0214816A3 (fr) 1988-11-23

Family

ID=16258065

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86306667A Withdrawn EP0214816A3 (fr) 1985-08-29 1986-08-28 Tubes à rayons cathodiques

Country Status (3)

Country Link
EP (1) EP0214816A3 (fr)
JP (1) JPS6251137A (fr)
KR (1) KR870002633A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0319328A3 (en) * 1987-12-04 1990-05-30 Rank Brimar Limited Electron guns for cathode ray tubes

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB467611A (en) * 1935-12-23 1937-06-21 Gen Electric Co Ltd Improvements in or relating to cathode ray tubes and apparatus comprising them

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0319328A3 (en) * 1987-12-04 1990-05-30 Rank Brimar Limited Electron guns for cathode ray tubes
US5034654A (en) * 1987-12-04 1991-07-23 Leyland John D Beam focusing means for a CRT electron gun assembly

Also Published As

Publication number Publication date
EP0214816A3 (fr) 1988-11-23
JPS6251137A (ja) 1987-03-05
KR870002633A (ko) 1987-04-06

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Inventor name: FURUI, KOICHIC/O PATENT DIVISION

Inventor name: KAKIZAKI, TAKEHIROC/O PATENT DIVISION

Inventor name: KUSUDA, KOUMEIC/O PATENT DIVISION