EP0205218B1 - Tube à rayons cathodiques à faisceau multiple et système comprenant un tel tube - Google Patents

Tube à rayons cathodiques à faisceau multiple et système comprenant un tel tube Download PDF

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Publication number
EP0205218B1
EP0205218B1 EP86200992A EP86200992A EP0205218B1 EP 0205218 B1 EP0205218 B1 EP 0205218B1 EP 86200992 A EP86200992 A EP 86200992A EP 86200992 A EP86200992 A EP 86200992A EP 0205218 B1 EP0205218 B1 EP 0205218B1
Authority
EP
European Patent Office
Prior art keywords
beams
deflection
cathode ray
lens
electron
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.)
Expired
Application number
EP86200992A
Other languages
German (de)
English (en)
Other versions
EP0205218A1 (fr
Inventor
Aart Adrianus Int. Octrooibureau B.V. Van Gorkum
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 EP0205218A1 publication Critical patent/EP0205218A1/fr
Application granted granted Critical
Publication of EP0205218B1 publication Critical patent/EP0205218B1/fr
Expired 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
    • 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
    • H01J29/51—Arrangements for controlling convergence of a plurality of beams by means of electric field only

Definitions

  • the invention relates to a multibeam cathode ray tube having in an evacuated envelope an electron-optical system centred around an axis and comprising means to generate at least two electron beams which are each focussed to form a spot on a display screen by means of common focussing means centred around the electron-optical axis and which are deflected over the display screen by means of deflection means, a common convergence lens centred around the axis being present between the means for generating the beams and the focussing means.
  • the invention also relates to a device comprising such a tube.
  • Multibeam cathode ray tubes are used, for example, as projection television display tubes or as tubes for displaying data (Data Graphic Display). They are also used for displaying television pictures and for photorecording.
  • the focussing means and/or the deflection means may be provided in or around the tube envelope. Focussing may be carried out, for example, by means of an accelerating lens or a unipotential lens in the envelope or by means of a magnetic focussing lens around the envelope or by means of a combination of these two lens types.
  • the deflection may be carried out by the means of deflection coils around the envelope or by means of deflection in the envelope.
  • a multibeam cathode ray tube for displaying data is known from United States Patent Specification 4,338,541. This specification describes that the beam aberrations are reduced if the focussing means and deflection means the distances from the beams to the tube axis are decreased.
  • the beam currents in such data display tubes are comparatively low (smaller than 100 pA overall current).
  • tubes having a much higher overall current (above 1 mA) are desired. If a good resolution (resolving power) is still to be achieved, special measures have to be taken.
  • Another object of the invention is to provide a device having such a tube in which during the deflection of the beams the distances between the spots on the display screen remain substantially constant.
  • a multibeam cathode ray tube of the kind described in the opening paragraph is characterized in that the convergence lens has such a strength that the beams overlap in the focussing and deflection means to such an extent that the distance between the axis of the outermost electron beam and the axis of the electron-optical system is at least five times smaller than the maximum diameter of the individual beams.
  • the convergence lens has such a strength that the beams overlap in the focussing and deflection means to such an extent that the distance between the axis of the outermost electron beam and the axis of the electron-optical system is at least five times smaller than the maximum diameter of the individual beams.
  • the invention is based on the recognition of the fact that the beam diameter upon passing the deflection and focussing means must be large to obtain the desired small spot dimensions. For a large number of electron beams this requires a comparatively large space unless, as is suggested, according to the invention the beams substantially overlap in the focussing and deflection means, i.e. the eccentricity of the beam is small as compared with the beam diameter in the deflection and focussing means.
  • one common focussing lens may be used so that all the beams are focussed to substantially the same extent and upon deflecting the beams substantially no distortion of the spot frame occurs.
  • a correct beam adjustment can be obtained by a suitable choice of the location of the point of convergence (crossing) of the beams. This adjustment depends on the location and type of the focussing and deflection means. This means that components such as lens deflection coil of a mono-beam tube may be used. Moreover, if this should be necessary, the shape of all the spots can be corrected simultaneously by one dynamic multipole corrector. Such a multipole corrector is placed in the proximity of the focussing and deflection means.
  • a first preferred embodiment of a multibeam cathode ray tube in accordance with the invention is characterized in that-viewed in the direction of propagation of the beams-the last electrode of the means for generating the beams is an apertured plate which extends substantially at right angles to the electron-optical axis and which is succeeded by the convergence lens which comprises at least two cylindrical lens electrodes centred around the axis, the diameter of the cylinders being at least twice as large as the maximum eccentricity of the apertures in the said plate. In that case substantially no abbera- tions are introduced into the beams.
  • the length of the first cylindrical lens electrode-viewed in the direction of propagation of the beams- is preferably smaller than the diameter of the said lens electrode.
  • the potentials at the lens electrodes of the convergence lens during the deflection may be varied so that the mutual distance of the targets on the display screen remains substantially constant during the deflection.
  • a multibeam cathode ray tube according to the invention is preferably used in a projection- television device.
  • Figure 1 is a diagrammatic longitudinal sectional view of a display tube according to the invention. It comprises a glass envelope 1 consisting of a neck 2, a funnel-like part 3 and a display window 4. A display screen 5 comprising luminescent material is provided on the inside of the display window.
  • an electron gun system 6 for generating at least two electron beams. The at least two generated electron beams are focussed on the display screen 5 by means of a focussing means (not shown in Figure 1).
  • the electron gun system 6 is connected to a source of control signals 8-via a connection 7-with which each electron gun is controlled.
  • the electron gun system is centred around the tube axis 9. The electron beams are deflected over the display screen by means of deflection means which are not shown in Figure 1.
  • FIG. 2a and 2b show diagrammatically the operation and construction of a tube having two electron beams 20 and 21 of which the lines of intersection of the beam envelopes with the plane of the drawing are shown.
  • the electron beams are generated by means of a number of cathodes situated in the plane 22, a control electrode 23 and an anode 24.
  • Anode 24 consists of a metal plate extending substantially at right angles to the tubes axis 9 and comprising apertures.
  • P-N cathodes which are situated in one plane. The use of a number of P-N cathodes is described in Netherlands Patent Application 830444 laid open to public inspection.
  • the cathodes may be situated in a row or in a matrix on a flat or curved surface and at equal or varying distances from each other.
  • the convergence lens is formed by two cylindrical lens electrodes 25 and 26 having a diameter of 10 mm and being centred around the axis 9.
  • the diameter of the said cylindrical electrode must be at least twice as large as the maximum eccentricity of the apertures in the said plate-shaped anode 24.
  • Equipotential lines are shown between the electrodes 24, 25 and 26.
  • the length of electrode 25 is smaller than the diameter and is 5 mm.
  • the length of electrode 26 is 20 mm.
  • the electron beams 20 and 21 are then focussed by the focussing means 27 and deflected over the display screen 28 by deflection means 29.
  • the distance A between electrode 26 and the display screen 28 in this case is 280 mm.
  • the distance B between electrode 26 and the focussing means 27 in this case is 100 mm.
  • Both magnetic and electrostatic components or combinations thereof may be used for the focussing and deflection. For example, focussing may be done electrostatically and deflection may be done magnetically or conversely. It is also possible to perform the focussing simultaneously electrostatically and magnetically.
  • the convergence lens has such a strength that the distance between the axis of the outermost electron beam 21 and the axis 9 is at least five times smaller than the (maximum) diameter of the individual beams 20 and 21 in the focussing and deflection area.
  • the diameter d takes the value of 7 mm.
  • one focussing lens may be used as a result of which all beams are focussed to substantially the same extent and substantially no distortion of the spot frame occurs during the deflection of the beams.

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Particle Accelerators (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)

Claims (6)

1. Tube à rayons cathodiques à faisceau multiple muni d'une enveloppe vidée d'air contenant un système électronique-optique centré autour d'un axe et contenant des moyens pour engendrer au moins deux faisceaux d'électrons qui sont focalisés chacun afin de former une tache sur un écran image à l'aide de moyens de focalisation communs et qui sont déviés sur l'écran image à l'aide de moyens de déviation, une lentille de convergence commune étant présente entre les moyens servant à engendrer les faisceaux et les moyens de focalisation, caractérisé en ce que la lentille de convergence commune présente une résistance telle que les faisceaux chevauchent dans les moyens de focalisation et de déviation de façon que la distance comprise entre l'axe du faisceau d'électrons extrême et l'axe du système électronique-optique soit au moins cinq fois plus grande que le diamètre maximal des faisceaux individuels.
2. Tube à rayons cathodiques à faisceau multiple selon la revendication 1, caractérisé en ce que vue dans la direction de propagation des faisceaux, la dernière électrode des moyens pour engendrer les faisceaux est une plaque perforée qui s'étend pratiquement perpendiculairement à l'axe électronique optique et qui est suivie de la lentille de convergence comprenant au moins deux électrodes de lentille cylindriques disposées de façon centrée autour de l'axe, le diamètre des cylindres étant au moins deux fois plus grand que l'excentricité maximale des ouvertures dans ladite plaque.
3. Tube à rayons cathodiques à faisceau multiple selon la revendication 1, caractérisé en ce que-vue dans la direction de propagation des faisceaux-la longueur de la première électrode de lentille cylindrique est plus petite que le diamètre de ladite électrode de lentille.
4. Tube à rayons cathodiques à faisceau multiple selon l'une des revendications précédentes, caractérisé en ce que ledit tube est un tube de reproduction de télévision par projection.
5. Dispositif comportant un tube à rayons cathodiques à faisceau multiple selon l'une des revendications précédentes et une alimentation par l'application de potentiels aux électrodes, caractérisé en ce que lors du fonctionnement du dispositif, les potentiels aux électrodes de lentille de la lentille de convergence pendant la déviation sont modifiés de façon que les distances mutuelles comprises entre les taches lumineuses sur l'écran image pendant la déviation restent pratiquement constantes.
6. Dispositif selon la revendication 5, caractérisé en ce qu'il comporte un dispositif de télévision par projection.
EP86200992A 1985-06-10 1986-06-09 Tube à rayons cathodiques à faisceau multiple et système comprenant un tel tube Expired EP0205218B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8501666 1985-06-10
NL8501666A NL8501666A (nl) 1985-06-10 1985-06-10 Multibundel-kathodestraalbuis en inrichting bevattende een dergelijke buis.

Publications (2)

Publication Number Publication Date
EP0205218A1 EP0205218A1 (fr) 1986-12-17
EP0205218B1 true EP0205218B1 (fr) 1989-10-18

Family

ID=19846114

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86200992A Expired EP0205218B1 (fr) 1985-06-10 1986-06-09 Tube à rayons cathodiques à faisceau multiple et système comprenant un tel tube

Country Status (5)

Country Link
EP (1) EP0205218B1 (fr)
JP (1) JPS61285644A (fr)
KR (1) KR870000742A (fr)
DE (1) DE3666523D1 (fr)
NL (1) NL8501666A (fr)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE788144A (fr) * 1971-08-31 1973-02-28 Gte Sylvania Inc Tube a rayons cathodiques du type couleur
US3798478A (en) * 1972-09-14 1974-03-19 Gte Sylvania Inc Multibeam cathode ray tube having a common beam limiting aperture therein
US4338541A (en) * 1979-12-07 1982-07-06 International Business Machines Corporation Multiple beam cathode ray tube having reduced off-axis aberrations

Also Published As

Publication number Publication date
EP0205218A1 (fr) 1986-12-17
DE3666523D1 (en) 1989-11-23
NL8501666A (nl) 1987-01-02
KR870000742A (ko) 1987-02-20
JPS61285644A (ja) 1986-12-16

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