EP0193983A1 - Tube de caméra de télévision avec un stigmateur pour correction du faisceau - Google Patents

Tube de caméra de télévision avec un stigmateur pour correction du faisceau Download PDF

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Publication number
EP0193983A1
EP0193983A1 EP86200249A EP86200249A EP0193983A1 EP 0193983 A1 EP0193983 A1 EP 0193983A1 EP 86200249 A EP86200249 A EP 86200249A EP 86200249 A EP86200249 A EP 86200249A EP 0193983 A1 EP0193983 A1 EP 0193983A1
Authority
EP
European Patent Office
Prior art keywords
stigmator
television camera
camera tube
electron
tube
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Withdrawn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
EP86200249A
Other languages
German (de)
English (en)
Inventor
Henricus Johannes INT. OCTROOIBUREAU B.V Van Rooy
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Gloeilampenfabrieken NV
Publication of EP0193983A1 publication Critical patent/EP0193983A1/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Withdrawn legal-status Critical Current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
    • H01J29/56—Arrangements for controlling cross-section of ray or beam; Arrangements for correcting aberration of beam, e.g. due to lenses
    • H01J29/566—Arrangements for controlling cross-section of ray or beam; Arrangements for correcting aberration of beam, e.g. due to lenses for correcting aberration

Definitions

  • the invention relates to a television camera tube comprising an electron gun, an electron-optical system for controlling and modulating an electron beam to be emitted by the electron gun, and a beam scanning system for scanning a target by means of the electron beam.
  • defects or aberrations occur in the electron beam due to the deflection of the beam during scanning, said defects usually increasing as the deflection angle is increased. Such defects are notably beam astigmatism and coma. Due to these defects, an electron spot becomes comparatively large notably at the corners of the target where it exhibits a poorly defined shape. Consequently, for example, the resolution of the tube at the periphery of the screen is considerably inferior to that in the central part thereof. If the spot shape at the centre is such that it does not limit the resolution in that region, a compromise can be accepted as regards the spot dimensions at the centre in order to achieve an improved spot shape at the corners. It will be apparent that this would be a bad compromise which cannot be used in systems requiring a high resolution such as high-definition television systems used for medical diagnostics. This is notably applicable to the television camera tube of such a system.
  • a television camera tube of the kind set forth in accordance with the invention is characterized in that a stigmator which dynamically precorrects the electron beam is added to the electron-optical system.
  • a stigmator for electron beam correction is known per se from Journal Ph. D. Vol. 7, 1974, pp. 805-814.
  • the electron beam can be precorrected in an angle-dependent manner so that an acceptable electron spot is also formed at the periphery of the screen.
  • the resolution across the entire screen is thus substantially increased and is also more uniform; for example, in diagnostic X-ray images the amount of image information is thus substantially increased so that the radiation dose for the patient can also be reduced.
  • the stigmator of a preferred embodiment consists of an eight-pole whose poles can be controlled in pairs.
  • the stigmator is constructed notably as an electromagnetic eight-pole. When an eight-pole stigmator is used, two pole pairs of the stigmator can also be used for beam alignment.
  • the precorrection can be automatically performed in a simple manner by measuring the control signals required for optimum correction across the entire screen once and by storing this data in a memory. This is notably applicable in as far as the correction is independent of the local image content, i.e. of the beam current and in this case a correction signal can be formed as a function of, for example, the excitation current for the deflection coils of an electron-optical deflection system.
  • a correction signal can be formed as a function of, for example, the excitation current for the deflection coils of an electron-optical deflection system.
  • Figure 1a of the drawing shows a television camera tube and Figure 1b shows an associated stigmator.
  • Figure 1a shows a television camera tube 1 comprising a cathode 2, a control grid 4, an anode 6, a final anode 8, a gauze anode 10 and a target 12. All said components are accommodated in an envelope 14 which comprises an entrance window 16 and a base 18 and serve to generate, control and modulate an electron beam 15 to be emitted by the cathode.
  • an electrical connection 20 for a signal electrode 22 and connections 24 for power supply and control of the electron gun are also provided around the tube there are provided deflection means, coils 26, which may may alternatively be provided in electrostatic form within the envelope, as well as focussing means, comprising coils 28, for which the same is applicable.
  • a stigmator 30 which in this case comprises (see Figure 1b) eight poles or rather four pairs of electromagnetic poles 32. T;he -field distribution and the operation of such a stigmator are described in detail in said article in Journ. Phys. D and will not be elaborated upon herein. Two non-adjacent coil pairs can be used for beam alignment in the tube, so that additional facilities in this respect can be dispensed with.
  • a stigmator which is arranged around the tube that its angular pasition can be optimized at a later stage; this benefits notably the beam alignment but may also be advantageous for the precorrection signal, because an optimum and combined positioning of the deflection coils and the stigmator can then be_performed. It may then be advantageous, for example to make two coil pairs coincide exactly with the diagonals of an image to be formed on the target. Notably for television systems in which the electron spot in the undeflected position can be made just small enough for it not to be the decisive factor determining the resolution, for example in a high-resolution system with a scanning raster with 1000 lines, a substantially improved image can thus be obtained.
  • a static precorrection imposed on the central spot offers only a rather imperfect correction for the deflected beam.
  • the invention can thus also be used to good advantage in systems in which the central spot is not the decisive factor in determining the resolution.
  • Such systems often utilize television camera tubes having an enlarged target so that, without using the invention, the desired gain in resolution is far from being achievable because of the larger deflection angles.
  • the invention again offers a high-resolution image across the entire screen in such a case.

Landscapes

  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
  • Electron Sources, Ion Sources (AREA)
EP86200249A 1985-02-22 1986-02-19 Tube de caméra de télévision avec un stigmateur pour correction du faisceau Withdrawn EP0193983A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8500500 1985-02-22
NL8500500A NL8500500A (nl) 1985-02-22 1985-02-22 Kathodestraalbuis met een stigmator voor bundelfoutcorrectie.

Publications (1)

Publication Number Publication Date
EP0193983A1 true EP0193983A1 (fr) 1986-09-10

Family

ID=19845571

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86200249A Withdrawn EP0193983A1 (fr) 1985-02-22 1986-02-19 Tube de caméra de télévision avec un stigmateur pour correction du faisceau

Country Status (3)

Country Link
EP (1) EP0193983A1 (fr)
JP (1) JPS61193341A (fr)
NL (1) NL8500500A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2693029A1 (fr) * 1992-06-29 1993-12-31 Sony Corp Canon à électrons pour tube cathodique couleur.
WO1996023316A1 (fr) * 1995-01-24 1996-08-01 International Business Machines Corporation Appareil de demodulation du balayage trame et procede correspondant
FR2754636A1 (fr) * 1996-10-15 1998-04-17 Thomson Tubes & Displays Systeme de deviation de faisceau d'electrons pour tube a rayons catholiques monochrome

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878416A (en) * 1953-08-10 1959-03-17 Pye Ltd Television camera tubes
US3150284A (en) * 1962-09-17 1964-09-22 Philco Corp Apparatus for use in conjunction with a cathode ray tube to reduce defocusing and astigmatism of an electron beam thereof
FR1396287A (fr) * 1964-05-28 1965-04-16 Philips Nv Dispositif pour convertir une image en un signal d'image électrique
GB1142747A (en) * 1966-01-03 1969-02-12 Gen Electric Improvements in electron optical systems
US3872344A (en) * 1972-09-15 1975-03-18 Tokyo Shibaura Electric Co Image pickup tube
US3961223A (en) * 1975-03-04 1976-06-01 United Technologies Corporation Astigmatic focus correction circuit

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878416A (en) * 1953-08-10 1959-03-17 Pye Ltd Television camera tubes
US3150284A (en) * 1962-09-17 1964-09-22 Philco Corp Apparatus for use in conjunction with a cathode ray tube to reduce defocusing and astigmatism of an electron beam thereof
FR1396287A (fr) * 1964-05-28 1965-04-16 Philips Nv Dispositif pour convertir une image en un signal d'image électrique
GB1142747A (en) * 1966-01-03 1969-02-12 Gen Electric Improvements in electron optical systems
US3872344A (en) * 1972-09-15 1975-03-18 Tokyo Shibaura Electric Co Image pickup tube
US3961223A (en) * 1975-03-04 1976-06-01 United Technologies Corporation Astigmatic focus correction circuit

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
IEEE TRANSACTIONS ON ELECTRON DEVICES, vol. ED-12, no. 8, August 1965, pages 478-484, IEEE, New York, US; K. SCHLESINGER et al.: "Correction of deflection-aberrations by analog computer" *
JOURNAL OF PHISICS D: APPLIED PHYISICS, vol. 7, 1974, pages 805-814, Letchworth, GB; N.H. DEKKERS: "A universal deflection unit generating a field of any order and azimuth" *
JOURNAL OF PHYSICS D: APPLIED PHYISICS, vol. 4, 1971, pages 27-38, Letchworth, GB; S.S. WILLDER: "The correction of deflection astigmatism in microspot cathode ray tubes" *
SOVIET INVENTIONS ILLUSTRATED, Week 84 50, abstract: LEEE, T 04, 84-311267/50, 30th January 1985, Derwent Publications Ltd., GB; & SU - A - 1 088 088 (LENGD ELECTROTECH RES) 23-04-1984 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2693029A1 (fr) * 1992-06-29 1993-12-31 Sony Corp Canon à électrons pour tube cathodique couleur.
WO1996023316A1 (fr) * 1995-01-24 1996-08-01 International Business Machines Corporation Appareil de demodulation du balayage trame et procede correspondant
US6268705B1 (en) 1995-01-24 2001-07-31 International Business Machines Corporation Raster demodulation apparatus and method
FR2754636A1 (fr) * 1996-10-15 1998-04-17 Thomson Tubes & Displays Systeme de deviation de faisceau d'electrons pour tube a rayons catholiques monochrome
WO1998016945A1 (fr) * 1996-10-15 1998-04-23 Thomson Tubes And Displays, S.A. Systeme de deviation de faisceaux d'electrons pour tubes cathodiques
US6300730B1 (en) 1996-10-15 2001-10-09 Thomson Tubes & Displays, S.A. Electron beam deflection system for cathode ray tubes

Also Published As

Publication number Publication date
JPS61193341A (ja) 1986-08-27
NL8500500A (nl) 1986-09-16

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Inventor name: VAN ROOY, HENRICUS JOHANNESINT. OCTROOIBUREAU B.V