US3678317A - Electron lens for convergence of plurality of beams - Google Patents

Electron lens for convergence of plurality of beams Download PDF

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Publication number
US3678317A
US3678317A US57481A US3678317DA US3678317A US 3678317 A US3678317 A US 3678317A US 57481 A US57481 A US 57481A US 3678317D A US3678317D A US 3678317DA US 3678317 A US3678317 A US 3678317A
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United States
Prior art keywords
screen
axis
beams
electrodes
transmitting
Prior art date
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Expired - Lifetime
Application number
US57481A
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English (en)
Inventor
Yoshizumi Terazawa
Kazuo Ayaki
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NEC Corp
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Nippon Electric Co Ltd
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Publication date
Application filed by Nippon Electric Co Ltd filed Critical Nippon Electric Co Ltd
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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
    • H01J29/58—Arrangements for focusing or reflecting ray or beam
    • H01J29/62—Electrostatic lenses
    • 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

Definitions

  • the electron spot coming out on the fluorescent screen spreads with a considerable amount of distortion when the electron beam ispassed through the outer portion of the electron lens. This resultsin loose resolution and has made the electron lens impracticable. in order to avoid the above-mentioned difficulties, the color television.
  • each electron 2 elongated opening and thus suitably compensating the conbeam may pass through the center portion of each electron lens, or has been provided with one electron lens so designed that all the electron beams may through the center portion of the electron lens or otherwise the diameters of the electron lens must increased.
  • the object of this invention is to provide an electrostatic electron lens, which with only little aberration, converges the electron beams passing through its edge portion.
  • F10. 1 is an optical model diagram illustrating the aberration in a conventional electron lens
  • F1G.2 is an optical model diagram illustrating the principles of the present invention
  • FlG.3 is an axial sectional diagram showing a specific em- 7 bodiment of the invention.
  • FTGS. 4,5 and 6 are plan views of components usable in An electron lens embodying this invention has as its element FIG 3.
  • such an electrode as having at least one elongated opening whose longitudinal direction is perpendicular to both the radial direction and the center axis of the electrode, in order that the electron beam off the center axis passes through said openings.
  • Said perpendicular direction will hereinafter be called lateral direction
  • the elongated opening disposed in the electrode of the electron lens according to this invention serves as a diverging lens having a relatively strong diverging effect in the radial direction of the electrode and a relatively weak diverging effeet in the lateral direction, to compensate the aberration in the electron lens.
  • E is an electric field on the side from which the electron beam enters the circular hole
  • E is an electric field on the side to which the electron beam 55 comes out of the circular hole.
  • the focal distance f with respect to the focusing action in the 0 transverse direction of the slit is expressed by the following equation when the potential Vand electric fields E and E are the same as above.
  • FlG.1 illustrates an optical model of a conventional electrc lens and some electron beams passing through the edge portion of the lens, wherein light rays 13, 14 and 15 parallel to the principal axis 12, after passing through a convex lens 11, and
  • a light beam having a circular section 16' on the plane 16 comes out to cast its cross section 17', 18 and 19' on the planes 17, 18 and 19, respectively, being refracted through the 0 direction.
  • F162 is an optical model showing the principles of this invention.
  • light rays 24, 25 and 26 parallel to the principal axis 22 and incident upon the convex lens 21, respectively, are shown as an optical model of electron rays passing through the edge portion of an electron lens.
  • a concave lens 23 having a stronger diverging effect in the direction parallel to the plane of the drawing than in the direction perpendicular to the plane of the drawing is shown as an optical model regarding the elongated opening of this invention.
  • the light rays 24,25 and 26 are suitably diverged and compensated by the concave lens 23 in the radim direction of the convex lens 21 and then are converged by the convex lens 21.
  • the focal distance of the slit is half that of the circular hole, and if E is larger than E in either case, then the focal distance will be negative and the small circular hole or the thin opening will work as a diverging lens.
  • FlG.3 is to illustrate the first embodiment of this invention.
  • the elongated opening becomes nearly circular or to be In FlG.3 an electron beam from the triode part consisting of a able to be considered as a circular hole, as the value of the length-breadth ratio of the elongated opening approaches l. While, the elongated opening becomes a slit as the lengthbreadth ratio increases.
  • a first grid electrode 302 and a second grid electrode 303 is moderately converged by a prefocus lens part formed between the second grid electrode 303 and third grid electrode 304.
  • the electron beam after passing length-breadth ratio, the focal distance of the elongated openthrough the elongated opening 305 disposed in the third grid lens type, and a positive high voltage is applied to thc third grid electrode 304 and fifth grid electrode 307, while, h fourth grid electrode 306 is held at nearly zero potential.
  • the electric field strength on h l ft f h elongated opening 305 of the third grid electrode 304 is negative and relatively small and that on the right is positive and relatively large. Therefore, the elongated opening 305 operates as a diverging lens.
  • the electric field on the left of the elongated opening 308 disposed in the fifth grid electrode 307 is negative and relatively large, and that on the right is nearly zero. Therefore-the elongated opening 308 operates also as a diverging lens. in F162 one diverging lens is used for compensation purpose. While, in theembodiment as in FlG.3, the both elongated openings 305 and 308 are used and have a diverging effect for compensation so that even strong aberration may be compensated. Accordingly, the main lens part may operate with little aberrationand good converging efiect on .the electron .beam 3.10passing through the. edgeportion. of the main lens.
  • the electron beam 310 comes out as a sufficiently small electron spot on the fluorescent screen 309.
  • FIG. 3 only one electron beam 310 is shown. Practically, however, three electron beams having circular sections (the lateral section of these electron beams are positioned at the vertex of an equilateral triangle) are used in the color television picture tube and, therefore, three pairs of elongated openings 305 and 308 must be provided.
  • FIG. 4 shows an arrangement of three elongated openings. These openings 42 are disposed so that their longitudinal directions are coincident with the lateral direction of the elec trode 41. It is necessary to suitably determine the lengthbreadth ratio of the elongated opening 42 for effective aberration compensation. It is also necessary to determine. the breadth (the narrower one of the distances across the opening) to be wide enough to pass the electron beam.
  • FlG.S shows the third and fifth grid electrodes of the second embodiment of the invention. These electrodes 51 are provided with are shaped elongated openings 52 which are disposed along the circumference of the electrodes.
  • each of the third and fifth grid electrodes 61 is provided with a circular hole 62 in the center, and also with areshaped elongated openings 63 disposed on the outer side of the circular hole 62.
  • This embodiment is an example applied to the color television picture tube of so-called inline type in which the lateral sections of three electron beams are aligned at equal intervals on one straight line.
  • the hole in the center is circular because the center electron beam passes through the center of the electron lens to cause little aberration and no compensation on aberration is needed.
  • the unipotential lens is employed.
  • other types oflenses for example, bipotential lens, may be used for aberration compensation according to this invention.
  • a cathode-ray tube comprising in combination:
  • a screen receivin said beams a plurality of hol ow electrodes separated by an open ended cylindrical electrode and spaced in tandem between said beam means and screen whereby said screen and electrodes are provided with acommon center axis; said electrodes energized with electric potentials of predetermined magnitudes for transmitting said beams therethrough on further axes spaced from said center axis to incidence with said center axis at points off said screen to cause an aberration of said beams at said screen; and
  • first and second of said electrodes provided with mutually opposing closed ends disposed perpendicularly to and coaxial with said center axis, each of said ends formed with elon gated openings equal in number to the number of said beams, each opening receiving a corresponding beam, and spaced from said center axis and provided with a preselected configuration, said openings haying preassigned maximum and minimum dimensions of which said minimum dimension is disposed in a radial direction relative to said center axis for transmitting all electrons of said respective beams said openings aligned in one plane for transmitting said respective beams to move said points to incidence with said center axis at said screen to compensate for said aberration.
  • a cathode-ray tube comprising in combination:
  • a plurality of hollow electrodes separated by an open ended cylindrical electrode and spaced in tandem between said beam means and screen whereby said electrodes are provided with an axis coincident with said one beam and screen axis; said electrodes energized with electric potentials of predetermined magnitudes for transmitting another of said beams through said electrodes on a further axis spaced from said electrode axis to incidence with said screen axis at a first point off said screen to cause an aberration ofsaid another beam;
  • first and second of said electrodes provided with mutually oppos ing closed ends disposed perpendicularly to and coaxially with said electrode axis; each of said ends formed with a central opening coaxial with said screen, one beam and electrode coincident axes for transmitting all electrons of said central one beam andwith at least one elongated opening spaced from said electrode axis and having maximum and minimum dimensions of which said minimum dimension is disposed in a radial direction relative to said electrode axis for transmitting all electrons of said another beam; said elongated openings aligned in one plane for transmitting said another beam to move said first incident point to coincidence with said screen axis at said screen to compensate for said aberration.

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US57481A 1969-07-25 1970-07-23 Electron lens for convergence of plurality of beams Expired - Lifetime US3678317A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5915069 1969-07-25

Publications (1)

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US3678317A true US3678317A (en) 1972-07-18

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US57481A Expired - Lifetime US3678317A (en) 1969-07-25 1970-07-23 Electron lens for convergence of plurality of beams

Country Status (5)

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US (1) US3678317A (enrdf_load_stackoverflow)
DE (1) DE2036479A1 (enrdf_load_stackoverflow)
FR (1) FR2055422A5 (enrdf_load_stackoverflow)
GB (1) GB1288101A (enrdf_load_stackoverflow)
NL (1) NL7011026A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4876295A (en) 1987-03-11 1989-10-24 The Dow Chemical Company Flexible thermoplastic epoxy resin and coatings prepared therefrom

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2696571A (en) * 1950-02-10 1954-12-07 Rca Corp Color kinescope
US3448316A (en) * 1967-01-14 1969-06-03 Sony Corp Cathode ray tube

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2696571A (en) * 1950-02-10 1954-12-07 Rca Corp Color kinescope
US3448316A (en) * 1967-01-14 1969-06-03 Sony Corp Cathode ray tube

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4876295A (en) 1987-03-11 1989-10-24 The Dow Chemical Company Flexible thermoplastic epoxy resin and coatings prepared therefrom

Also Published As

Publication number Publication date
GB1288101A (enrdf_load_stackoverflow) 1972-09-06
FR2055422A5 (enrdf_load_stackoverflow) 1971-05-07
DE2036479A1 (de) 1971-09-23
NL7011026A (enrdf_load_stackoverflow) 1971-01-27

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