US2336895A - Cathode ray tube - Google Patents

Cathode ray tube Download PDF

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Publication number
US2336895A
US2336895A US403570A US40357041A US2336895A US 2336895 A US2336895 A US 2336895A US 403570 A US403570 A US 403570A US 40357041 A US40357041 A US 40357041A US 2336895 A US2336895 A US 2336895A
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United States
Prior art keywords
plate
plates
splitter plate
electron beam
cathode ray
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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
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US403570A
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English (en)
Inventor
Shelton Edward Eric
Moss Hilary
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AC Cossor Ltd
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AC Cossor Ltd
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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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/50—Electron guns two or more guns in a single vacuum space, e.g. for plural-ray tube
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/48—Electron guns
    • H01J2229/50—Plurality of guns or beams
    • H01J2229/507—Multi-beam groups, e.g. number of beams greater than number of cathodes

Definitions

  • This invention relates to the double beam cathode ray tube of the kind in which a single beam is generated in an electron gun and is then divided into two parts by an electrostatic shield, which will be referred to as a splitter plate, disposed in the path of the beam between the lirst (or the only) pair of deiiector plates.
  • the two parts of the beam are rendered independently deiiectable in one direction by the shielding action of this splitter plate.
  • the beam is necessarily generated and focussed, ⁇ at least mainly, by electron lenses, because the beam of a tube employing only gas focussing is not sufficiently wide for a splitter plate to be permissible. A small quantity of gas may, however, be admitted to improve the focus.
  • intermodulation will be applied to the defect found in tubes of the kind described, that each part of the beam is to some extent deflected in accordance with variations in the potential of the deector plate from which it is shielded by the splitter plate. Compensation for one form of intermodulation may be ef modulation, which may be experienced in such a tube when the deiiector plate circuits are of high impedance, can be ascribed to the collection by the deflector plates of secondary electrons emitted from the splitter plate. Secondary electrons may be emitted from the edge of the splitter plate nearest to the gun, or from the sides of this plate.
  • the secondary electron current which flows from the splitter plate to either one deflector plate is rendered substantially independent of the potential of the other deflector plate.
  • the splitter plate is a metallic plate having a carbonized surface. This feature may be used in conjunction with, or independently of, other features of the invention.
  • the splitter plate is extended towards the cathode beyond the entrance edges of those deflector plates between which it is disposed. This reduces the penetration of the iield of either deflector plate into the region at the entrance edge of the splitter plate and into the region between this edge and the other deflector plate, and hence reduces the tendency to collection by either deector plate of secondary electrons emitted in these regions. It is essential, however, to avoid appreciable penetration of the splitter plate into any electrostatic focussing field, although penetration into any electromagnetic focussing field is immaterial provided that the splitter plate is of non-magnetic material.
  • an apertured disc electrode maintained at the potential of the splitter plate, and disposed normally to the axis, shall be arranged to touch, or almost to touch, the entrance edge of the splitter plate, to reduce still further the penetration of the deector plate iields.
  • the splitter plate may be provided with an extension which reaches within the aperture of this disc.
  • Such an apertured disc may serve also as a part of the final anode of the electron gun.
  • FIG. 1 is a sectional view taken on the plane containing the axis and parallel to the direction of Y deection.
  • Figure 2 is a sectional View on the plane perpendicular to the axis, indicated at A-A in Figure l.
  • Figure 3 is a sectional View taken on the plane containing the axis and parallel to the direction of X deection.
  • the beam is generated in an electron gun and is Iinally focussed by the electrostatic electron lens formed between the last two anodes I and 2 of the gun.
  • the nal anode 2 comprises the disc 2a, having a central aperture 2b through which the beam issues to pass on both sides of the splitter plate 3.
  • This splitter palte 3 is disposed between the Y deflector plates il and 5 and shields each part of the beam from the deiiector plate on the opposite side.
  • the plate 3 is maintained at the same potential as, and is made long enough to touch, or almost to touch, disc 2a.
  • the plate 3 may have its surface carbonized, in manner known per se, to reduce the tendency tu secondary electron emission therefrom.
  • Y plates 4 and 5 are supported by the gripping of the ends of their flanges 4a, 5a between micas 29 and Sil. They are positioned relative to mica 3l! by their lugs 4b, 4c, 5b, 5c fitting into slots in the circular inner edge of mica 30.
  • connection to Y plate 4 is' provided through the short lead I8, by which its lug ibis joined to the support rod 8.
  • the bucking .wire or' deector element 'I is supported by rods 8 and II.
  • Rod 8 is carried right down to the cathode end of the structure and is connected through a leadin wire to ar: external Contact. Similarly.
  • bucking wire or deiiector element 6 is supported by rods I2 and I5, one of which is carried right down to the cathode' end' of the structure and is connected through a lead-in wire to an external contact.
  • X plate 20 is supported'by the rods Il and I4,
  • rod I 4 is carried down'and connected to an' external contact.
  • the other X plate 4I! is similarly supported from rods I Il and I3, one of which is carried down and connected to an external contact.
  • interplate shields 2l and 24 disposed substantially perpendicular to the axis. mounted on micas 29V and 28 respectively and both maintained at the potential of the nal anode 2.
  • are bent up as plates parallel to the axis which reach up to the mica 28.
  • has a large rectangular central aperture and the edges 2Ic and 2Id are bent up as plates parallel to the axis at the sides of this aperture.
  • plates 22a and 22h are provided par'- allel to the axis and extending from the top surface of shield 2lv up tothe mica 28.
  • interplate shield 24 Parts of the interplate shield 24 near to the beam-are arched, as indicated at 24a. into a curvature struck from a centre substantially at the apparent centre of Ydeflection.
  • the interplate shield 24 is secured to the mica 28 by lugs 24h which are inserted through holes in the mica and bent back along its under-surface.
  • v VA short lead 23 previously welded to such a lug 24U, is connected to plate 21a to connect the interplate shields 2
  • Shield 2I is connected by ashort lead 23a to the wire I5, which is carried down to the cathode end of the structure andV connected through a lead-in wire to an external contact.
  • I4 between the micas 28 and 29 are shielded from splitter plate 3 by plates 2Ia, 2Ib.
  • the potential of one of the Y plates was maintained 12 volts positive with respect to the splitter plate, and the potential of the other Y plate was varied over the range from 50 volts negative to 50 volts positive with respect to the
  • the secondary electron current whichl flowed'from the splitter plate to the first Y plate varied between 2.30 and 4.10 microamperes in the tube having no shielding, but in the tube according to the invention the variation was reduced to the limits 2.25 and 2.65 microamperes.
  • A- further type of distortion or" the traces of the electron beams is due to secondary electrons returning from the iuorescent screen being collected by the'Y plates l and 5 during the periods when the potentials of the X plates are nearly equal. If either of the Y plates is connected to a high impedance circuit, such a current of secondary electrons will produce an appreciable variation of potential. This effect may be reduced to negligible proportions by maintaining the hood 21 at a potential of say 35 volts positive to the nal anode 2, so that it collects practically all the secondary electrons returning from the screen. For this purpose the wire I'I is connected to the hood 2l and carried down to an external contact.
  • a cathode ray tube the combination of an electron gun for emitting an electron beam comprising an anode having an aperture therein through whichsaid electron beam passes, a pair of deiiector plates between which said electron beam passes, a splitter plate positioned intermediate said deflector plates in the path of said electron beam whereby the said beam is divided into two parts which pass respectively on each side of the splitter plate, said splitter plate comprising a metallic electrode having a carbonized surface.
  • a cathode ray tube comprising an electron gun for emitting an electron beam, an anode having an aperture therein through which said electron beam passes, a pair of deilector plates between which said electron beam passes, a splitter plate positioned intermediate said deiiector plates in the path of said electron beam whereby the said electron beam is divided into two parts which pass respectively on each side of the splitter plate, said splitter plate extending towards the said anode beyond the entrance edges of the said deflector plates between which the said splitter plate is disposed.
  • an electron gun for emitting an electron beam comprising an anode having an aperture therein through which said electron beam passes, a pair of delector plates between which said electron beam passes, a splitter plate positioned intermediate said deflector plates in the path of said electron beam whereby the said electron beam is divided into two parts which pass respectively on each side of the splitter plate, said splitter plate extending towards the said anode beyond the entrance edges of the said deiiector plates between which the said splitter plate is disposed.
  • a cathode ray tube comprising an electron gun for emitting an electron beam, an anode having an aperture therein through which said electron beam passes, a pair of deector plates between which said electron beam passes, a splitter plate positioned intermediate said deector plates in the path of said electron beam whereby said electron beam is divided into two parts each of which passes respectively on a side of the splitter plate, the entrance edge of said splitter plate being positioned in contact with said anode.
  • an electron gun for emitting an electron beam comprising an anode having an aperture therein through which said electron beam passes, a pair of deector plates between which said electron beam passes, a splitter plate positioned inter.- mediate said deiiector plates in the path of said electron beam whereby said electron beam is divided nto two parts each of which passes respectively on a side of the splitter plate, the entrance edge of said splitter plate being positioned in contact with said anode.
  • a cathode ray tube comprising an electron gun for emitting an electron beam, an anode having an aperture therein through which said electron beam passes, a pair of deector plates between which said electron beam passes, a splitter plate positioned intermediate said deflector plates in the path of said electron beam whereby said electron beam is divided into two parts each of which passes respectively on a side of the splitter plate, said splitter plate comprising an extension which extends within the aperture of said anode.
  • a cathode ray tube comprising an electron gun for emitting an electron beam, an anode having an aperture therein through which said electron beam passes, a pair of deflector plates between which said electron beam passes, means for supporting said deector plates electrically connected thereto, a splitter plate positioned intermediate said defiector plates in the path of said electron beam whereby the said beam is divided into two parts which pass respectively on each side of the splitter plate, and means for electrostatically shielding said splitter plate from said aforementioned means.
  • a cathode ray tube comprising an electron gun for emitting an electron beam, means comprising a splitter plate for dividing said electron beam into a plurality of parts, means comprising a pair of deector plates cooperating with said splitter plate for independently deflecting each of said parts, deiiector elements each connected to opposite deflector plates and means for electrostatically shielding said deflector elements from said splitter plate.
  • a cathode ray tube comprising an electron gun for emitting an electron beam, an anode having an aperture therein through which said electron beam passes, means to divide the beam into a plurality of parts and to control independently the deflection of said parts in one plane comprising a pair of dei-lector plates between which said electron beam passes and a splitter plate positioned intermediate said deiiector plates in the path of said electron beam whereby the said electron beam is divided into two parts which pass respectively on each side of the splitter plate, a pair of deilector plates between which said electron beam parts pass which serves to control the deiiection of said beam parts in another plane and shielding means comprising a metallic shield surrounding said pairs of deflector plates and said splitter plate.

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  • Electron Sources, Ion Sources (AREA)
  • Solid Thermionic Cathode (AREA)
US403570A 1940-07-23 1941-07-22 Cathode ray tube Expired - Lifetime US2336895A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB12050/40A GB553131A (en) 1940-07-23 1940-07-23 Improvements in cathode ray tubes

Publications (1)

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US2336895A true US2336895A (en) 1943-12-14

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US (1) US2336895A (de)
BE (1) BE482112A (de)
GB (1) GB553131A (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2425682A (en) * 1943-08-19 1947-08-12 Cathodeon Ltd Cathode-ray tube with shielded deflecting plates
US2757301A (en) * 1952-07-30 1956-07-31 Westinghouse Electric Corp Three beam gun
US2802139A (en) * 1953-05-30 1957-08-06 Int Standard Electric Corp Gun system for cathode ray tubes
US2921228A (en) * 1954-05-18 1960-01-12 Itt Color television apparatus
US2950406A (en) * 1954-05-10 1960-08-23 Philco Corp Precision cathode-ray tube assembly
US3072786A (en) * 1963-01-08 Beam splitter
US3368096A (en) * 1963-08-31 1968-02-06 Matsushita Electronics Corp Deflection plates coated with secondary electron emissionsuppressing metal
US4080546A (en) * 1974-10-16 1978-03-21 Steigerwald Strahltechnik Gmbh Beam splitter for electron beam machines
EP0010326A1 (de) * 1978-10-12 1980-04-30 Koninklijke Philips Electronics N.V. Bildröhre für Farbfernseher

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3072786A (en) * 1963-01-08 Beam splitter
US2425682A (en) * 1943-08-19 1947-08-12 Cathodeon Ltd Cathode-ray tube with shielded deflecting plates
US2757301A (en) * 1952-07-30 1956-07-31 Westinghouse Electric Corp Three beam gun
US2802139A (en) * 1953-05-30 1957-08-06 Int Standard Electric Corp Gun system for cathode ray tubes
US2950406A (en) * 1954-05-10 1960-08-23 Philco Corp Precision cathode-ray tube assembly
US2921228A (en) * 1954-05-18 1960-01-12 Itt Color television apparatus
US3368096A (en) * 1963-08-31 1968-02-06 Matsushita Electronics Corp Deflection plates coated with secondary electron emissionsuppressing metal
US4080546A (en) * 1974-10-16 1978-03-21 Steigerwald Strahltechnik Gmbh Beam splitter for electron beam machines
EP0010326A1 (de) * 1978-10-12 1980-04-30 Koninklijke Philips Electronics N.V. Bildröhre für Farbfernseher

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Publication number Publication date
GB553131A (en) 1943-05-10
BE482112A (de)

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