EP0319402B1 - Verwendung einer Elektronenkanone für eine Kathodenstrahlröhre - Google Patents

Verwendung einer Elektronenkanone für eine Kathodenstrahlröhre Download PDF

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Publication number
EP0319402B1
EP0319402B1 EP88403008A EP88403008A EP0319402B1 EP 0319402 B1 EP0319402 B1 EP 0319402B1 EP 88403008 A EP88403008 A EP 88403008A EP 88403008 A EP88403008 A EP 88403008A EP 0319402 B1 EP0319402 B1 EP 0319402B1
Authority
EP
European Patent Office
Prior art keywords
electrode
acceleration
supplementary
electron gun
lens
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 - Lifetime
Application number
EP88403008A
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English (en)
French (fr)
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EP0319402A1 (de
Inventor
Jacques Chevalier
Jean-Pierre Sembely
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.)
Thales SA
Original Assignee
Thomson CSF SA
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Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
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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
    • H01J29/46—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

Definitions

  • the invention relates to the use of an electron gun for cathode ray tubes of the beam focusing type either by magnetic lens or by electrostatic lens, having a high resolution and a high luminance according to the first part of claim 1 .
  • a cathode ray tube is the assembly constituted by a vacuum enclosure inside which is placed an electron gun producing a beam of electrons which bombard a luminescent screen.
  • the electron gun has a set of electrodes and possibly deflection plates.
  • the electron source is conventionally constituted by an alkaline earth oxide cathode heated by a filament.
  • the thermionic emission of electrons is stimulated by an electric field created between the cathode and the acceleration electrode.
  • a control electrode or Wehnelt constituted by a metallic cup surrounding the cathode and having a small diameter orifice in the axis of the tube, makes it possible to modify the electric field and to control the intensity of the electrons emitted and consequently the current of beam and finally the trace luminance of the screen.
  • an electron gun such as that shown in FIG. 1 is conventionally used.
  • This gun comprises an electron source electrode or emissive cathode 1, a Wehnelt or control electrode 2, a first acceleration electrode or anode 3, then an electrode 4 which may be, as the case may be, a final acceleration electrode or a focusing electrode.
  • Each electrode is in operation subjected to a respective bias voltage V1, V2, V3, V4 and possibly V5 in case there is both an electrode final acceleration and a second focusing electrode.
  • a main focusing lens is constituted, as the case may be, by a magnetic lens placed outside the neck of the tube or by a lens electrostatic formed for example by electrodes 4 and 5.
  • Polarization voltages V3 and V4 are applied in operation in a voltage ratio V4 / V3 which can be, depending on the type of gun, high (of the order of 15) or low (of the order of 5 to 8).
  • Polarization voltages V5 and V4 are applied, in operation, in a low voltage ratio V5 / V4 (of the order of 4 to 6).
  • the anode electrode 3 has a planar face or preferably an entry plane disc 13 pierced at its center with a circular orifice 17.
  • the first focusing electrode 4 has a planar face or preferably a planar disc entry 14 also pierced with a circular hole 18 in its center.
  • the input discs 13 and 14 of the electrodes 3 and 4 are mutually parallel and orthogonal to the axis of the electron beam 21 passing through their center.
  • the first focusing electrode 4 has a planar face or preferably an outlet plane disc 15 and the second focusing electrode 5 has a planar face or preferably an inlet plane disc 16.
  • the two discs 15, 16, each pierced with 'a circular orifice 19 and 20 in their center, are mutually parallel and orthogonal to the axis of the electron beam 21 passing through their center.
  • the pre-focusing lens is therefore formed by the parallel disks 13 and 14 of the electrodes 3 and 4 provided with their orifices.
  • the second lens, or main lens is formed by the parallel discs 15 and 16 of the electrodes 4 and 5 provided with their orifices.
  • the V5 / V4 voltage ratio may be low compared to the V4 / V3 voltage ratio.
  • the power of said second lens is sufficient to ensure the main focusing.
  • the inlet 18 of the electrode 4 is constituted by a circular hole of small diameter. This causes a curvature of the field lines and a pinching of the beam at its level.
  • the second lens, or main lens forms on the screen the image of an object whose position and diameter vary little with the flow rate of the cathode thus ensuring a small variation in the size of the spot on the screen.
  • the deflection of the electron beam is obtained by means of any conventional deflector not shown in FIG. 1.
  • a control voltage V2 is applied to the Wehnelt electrode. For a certain value of V2, we manage to cancel the cathode current. This value of V2 is called blocking voltage.
  • the blocking voltage of the electron beam depends on the dimensions of the elements constituting the barrel, in particular the distances between the cathode-Wehnelt and Wehnelt-anode electrodes and the diameters of the orifices of the entry face of each of these electrodes.
  • this blocking voltage never takes exactly the same value for each tube manufactured due to manufacturing tolerances.
  • the dispersion of this existing blocking voltage between different tubes of the same model requires adjustment. This adjustment can be made on the voltage V2 of the control electrode. However, it is generally preferred to carry out this adjustment from the bias voltage V3 of the anode because it is easier to obtain an adjustable power supply for the anode bias voltage than for the voltage of the control electrode.
  • the present invention overcomes these problems by proposing the use of an electron gun in which an additional electrode is inserted between the first acceleration electrode or anode and the focusing electrode, this additional electrode having a voltage of fixed polarization, the value of which lies within the adjustment range of the anode polarization voltage.
  • the present invention therefore relates to the use of an electron gun for cathode ray tubes comprising successively an electron source electrode or cathode, a control electrode or Wehnelt, a first acceleration electrode or anode brought to a voltage adjustable and at least one focusing or second acceleration electrode, an additional electrode inserted between the first acceleration electrode or anode and the focusing electrode; characterized in that this additional electrode is brought to a fixed bias voltage, the additional electrode constituting with the electrode of first acceleration, a first low-power pre-focusing lens and constituting with the focusing electrode a pre-focusing lens strong power.
  • FIG. 1 shows the diagram of an electron gun according to the prior art. This figure has already been described and will not be further detailed.
  • FIG 2 shows the partial diagram of an electron gun according to the invention. Only the part comprising all of the electron source, control, first acceleration, focusing electrodes and to which the invention relates has been shown. These electrodes are placed in the vacuum enclosure 6.
  • the electron gun has a succession of electrodes or the electrode 1 is an emissive cathode, the electrode 2 is a control electrode or Wehnelt, the electrode 3 is a first acceleration electrode or anode, the electrode 30 is a focusing electrode, the electrode 4 is a focusing electrode also producing a second acceleration.
  • the barrel may also include another electrode to achieve a third acceleration such as the electrode 5 shown in Figure 1 of the prior art.
  • Each electrode is, in operation, subjected to a respective bias voltage V1, V2, V3, V30, V4.
  • the electrode 3 and the electrode 30 form a low power prefocus lens, while the electrode 30 and the electrode 4 form a high power prefocus lens.
  • a prefocusing of the electron beam is obtained by means of the first prefocusing lens formed by the electrodes 3 and 30 which has a weak action and by the second prefocusing lens formed by the electrodes 30 and 4.
  • the additional electrode which is constituted by the electrode 30, is placed between the anode 3 and the electrode 4, this electrode 30 having a bias voltage V30 whose value is situated in the range of adjustment of the anode bias voltage.
  • the tensions of polarization applied during operation to the electrodes 3 and 30 are in a low V30 / V3 ratio, V3 being substantially equal to V30 to within 30%.
  • the bias voltages applied during operation to the electrodes 30 and 4 are in a high V4 / V30 ratio, greater than or equal to 10.
  • the bias voltage V3 of the anode electrode 3 is adjustable and can be adjusted to obtain the voltage desired blocking of electrons.
  • the anode electrode 3 has a planar face which is preferably an entry plane disc 13 pierced in its center with a circular orifice 17. This electrode has a rear face 21 fully open and which is opposite with the front face 31 of the electrode 30.
  • the electrode 30 has a rear face constituted by a flat disc 32 pierced with a circular orifice 33.
  • the electrode 4 has a front face 40 facing the rear face 32, pierced with orifices 41.
  • the front and rear faces of each of the electrodes are mutually parallel and orthogonal to the axis XX ′ of the electron beam 7.
  • the addition of the fixed polarization electrode 30, opposite the electrode 4 and the choice of polarizations so that the ratio of these polarization voltages is high makes it possible to obtain a lens powerful which ensures focusing of the electron beam, the beam having a small diameter over its entire length at the exit of the electrostatic lens 30-4.
  • the addition of the electrode 30 also makes it possible to be able to adjust the bias voltage of the anode in order to adjust the blocking voltage of the electron beam without modifying the characteristics of the beam, these modifications being reflected in the prior art either by poor performance or by poor resolution.
  • the lenses formed by the electrodes 3 and 30 and by the electrodes 30 and 4 have a large diameter, and thus ensure a pre-focusing of the beam without providing aberration of sphericity on the screen, and thus provides good resolution and good luminance.
  • the diameters of the orifices of the electrodes 2 and 3 are of the same order of magnitude as in a conventional gun.
  • the diameter of the openings 21 and 31 is of the order of magnitude of the outside diameter of the electrodes which are of cylindrical shape.
  • the diameter of the orifices 33 and 41 are of the same order of magnitude and can be chosen between 2 and 6mm.
  • the distance between the faces 32 and 40 of the electrodes 30 and 4 is of the order of 0.2 to 1 mm.
  • the distance between point A of the thinning area located in the space between the electrodes 2 and 3, and the disc 32 of the electrode 30 is between 5 and 10 mm.

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  • Electron Sources, Ion Sources (AREA)

Claims (5)

1. Verwendung einer Elektronenkanone für Kathodenstrahlröhren, die hintereinander eine Elektronenquellenelektrode oder Kathode (1), eine Steuer- oder Wehnelt-Elektrode (2), eine Erstbeschleunigungselektrode oder Anode (3), die auf einer einstellbaren Spannung gehalten wird, und wenigstens eine Fokussierungs- oder Zweitbeschleunigungselektrode (4) aufweist, wobei eine zusätzliche Elektrode (30) zwischen die Erstbeschleunigungselektrode oder Anode (3) und die Fokussierungs- oder Zweitbeschleunigungselektrode (4) eingesetzt ist, dadurch gekennzeichnet, daß die zusätzliche Elektrode (3) auf einer festen Polarisationsspannung (V30) gehalten wird, wobei die zusätzliche Elektrode mit der Erstbeschleunigungselektrode (3) eine erste Vorfokussierungslinse mit schwacher Leistung und mit der Fokussierungselektrode (4) eine Vorfokussierungslinse mit hoher Leistung bildet.
2. Verwendung einer Elektronenröhre für Kathodenstrahlröhren gemäß Anspruch 1, dadurch gekennzeichnet, daß die Polarisationsspannung (V30), auf der die zusätzliche Elektrode gehalten wird, um einen Faktor von etwa 10 unter der Polarisationsspannung der Fokussierungselektrode (4) liegt und im wesentlichen bis auf 30% gleich der Polarisationsspannung ist, auf der die erste Beschleunigungselektrode (3) gehalten wird.
3. Verwendung einer Elektronenkanone für Kathodenstrahlröhren gemäß Anspruch 1 oder 2, in der die Steuerelektrode (2) und die Erstbeschleunigungselektrode (3) von zylindrischen Bauteilen gebildet sind, die einander gegenüberliegende Stirnseiten aufweisen, von denen jede ein kreisförmiges Loch mit vorgegebenem Durchmesser besitzt, deren Mittelpunkte sich auf derselben Achse XX′ befinden, dadurch gekennzeichnet, daß die zusätzliche Elektrode (30) und die Zweitbeschleunigungselektrode (4) von zylindrischen Bauteilen gebildet wird, die jeweils einander gegenüberliegende ebene Stirnseite (32, 40) aufweisen, die jeweils eine Öffnung (33, 41) mit kleinem Durchmesser besitzen, die die Linse mit hoher Leistung bilden, wobei die zusätzliche Elektrode (30) und die Erstbeschleunigungselektrode (3) einander gegenüberliegende Löcher (21, 31) aufweisen, die die Linse mit geringer Leistung bilden, wobei die Mittelpunkte der Löcher und Öffnungen auf der Achse XX′ angeordnet sind; wobei die Polarisationsspannung V3 der Erstbeschleunigungselektrode (3) gleich der Polarisationsspannung (V30) der zusätzlichen Elektrode plus oder minus 30% dieses Wertes ist und wobei das Verhältnis (V4/V30) zwischen der Polarisationsspannung V4 der Zweitbeschleunigungselektrode (4) und der zusätzlichen Elektrode größer als 10 ist.
4. Verwendung einer Elektronenkanone gemäß Anspruch 2 oder 3, in der zwischen den ebenen Stirnseiten der Steuerelektrode (2) und der Erstbeschleunigungselektrode (3) ein eingeschnürter Querschnitt des Bündels erzeugt wird, dadurch gekennzeichnet, daß der Abstand zwischen dem Mittelpunkt (A) dieses eingeschnürten Querschnittes und der Linse mit hoher Leistung, die von der zusätzlichen Elektrode (30) und der Zweitbeschleunigungselektrode (4) gebildet wird, in der Größenordnung zwischen 5 und 10 mm liegt.
5. Verwendung einer Elektronenkanone gemäß Anspruch 3, dadurch gekennzeichnet, daß der Durchmesser der einander gegenüberliegenden Blenden (21, 31) der Erstbeschleunigungselektrode (3) und der zusätzlichen Elektrode (30) in der Größenordnung des Durchmessers dieser Elektroden liegt.
EP88403008A 1987-12-01 1988-11-30 Verwendung einer Elektronenkanone für eine Kathodenstrahlröhre Expired - Lifetime EP0319402B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8716635A FR2623939B1 (fr) 1987-12-01 1987-12-01 Canons a electrons pour tube a rayonnement cathodique
FR8716635 1987-12-01

Publications (2)

Publication Number Publication Date
EP0319402A1 EP0319402A1 (de) 1989-06-07
EP0319402B1 true EP0319402B1 (de) 1992-06-10

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EP88403008A Expired - Lifetime EP0319402B1 (de) 1987-12-01 1988-11-30 Verwendung einer Elektronenkanone für eine Kathodenstrahlröhre

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US (1) US4914724A (de)
EP (1) EP0319402B1 (de)
JP (1) JPH01186539A (de)
DE (1) DE3871918T2 (de)
FR (1) FR2623939B1 (de)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2646017A1 (fr) * 1989-04-18 1990-10-19 Thomson Tubes Electroniques Canon a electrons pour tubes a rayons cathodiques a haute resolution
JP3147227B2 (ja) * 1998-09-01 2001-03-19 日本電気株式会社 冷陰極電子銃
US6605898B2 (en) * 2001-01-16 2003-08-12 Matsushita Electric Industrial Co., Ltd CRT device with improved resolution
JP2005501378A (ja) * 2001-08-28 2005-01-13 コーニンクレッカ　フィリップス　エレクトロニクス　エヌ　ヴィ Ｈｅ−ｃｒｔのプリフォーカスレンズ
JP4298399B2 (ja) * 2003-06-26 2009-07-15 キヤノン株式会社 電子線装置及び該電子線装置を用いた電子線描画装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2201536B1 (de) * 1972-09-26 1976-08-13 Thomson Csf
FR2355373A1 (fr) * 1976-06-15 1978-01-13 Thomson Csf Canon a electrons perfectionne, et tube a rayons cathodiques comportant un tel canon, notamment pour dispositif de visualisation
JPS55102159A (en) * 1979-01-30 1980-08-05 Mitsubishi Electric Corp Color cathode ray tube

Also Published As

Publication number Publication date
FR2623939B1 (fr) 1990-03-09
FR2623939A1 (fr) 1989-06-02
DE3871918D1 (de) 1992-07-16
EP0319402A1 (de) 1989-06-07
US4914724A (en) 1990-04-03
DE3871918T2 (de) 1992-12-24
JPH01186539A (ja) 1989-07-26

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