US2917658A - Electron discharge devices - Google Patents

Electron discharge devices Download PDF

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Publication number
US2917658A
US2917658A US616293A US61629356A US2917658A US 2917658 A US2917658 A US 2917658A US 616293 A US616293 A US 616293A US 61629356 A US61629356 A US 61629356A US 2917658 A US2917658 A US 2917658A
Authority
US
United States
Prior art keywords
electrode
gun
lens
electrons
envelope
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
US616293A
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English (en)
Inventor
Roger W Hunter
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.)
TDK Micronas GmbH
International Telephone and Telegraph Corp
Original Assignee
Deutsche ITT Industries GmbH
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
Priority to BE569304D priority Critical patent/BE569304A/xx
Application filed by Deutsche ITT Industries GmbH filed Critical Deutsche ITT Industries GmbH
Priority to US616293A priority patent/US2917658A/en
Priority to GB31786/57A priority patent/GB869814A/en
Application granted granted Critical
Publication of US2917658A publication Critical patent/US2917658A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
    • H01J31/18—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen with image written by a ray or beam on a grid-like charge-accumulating screen, and with a ray or beam passing through and influenced by this screen before striking the luminescent screen, e.g. direct-view storage tube

Definitions

  • This invention relates to electron discharge devices and is particularly directed to devices with an extended target area and an electron gun for uniformly bombarding or flooding the area.
  • the electron image of a video signal is Written on a planar storage target screen electrode and the image is then transferred to a closely spaced phosphor anode by a low density flood beam of electrons.
  • a flood beam impinge upon the screen normal to the plane of the screen and that the density of electrons beuniform throughout the target screen area.
  • the cathode for supplying the flood beam is small in size compared to the screen area to be served.
  • the electron source may be considered a point source of electrons.
  • the object of this invention is an improved display tube with means for providing a flood beam which is uniform in density and is well collimated throughout the planar area to be flooded.
  • a display tube having a planar target screen electrode, a writing gun for scanning and writing an electron image on the planar electrode and a flood gun spaced from the center of the electrode on a line substantially perpendicular to the center of the electrode for flooding the planar electrode with electrons, characterized in that a negative electron lensconcentric with said line is disposed adjacent said floodgunfor diverging the beam of the gun, and a double positive electron lens concentric with said line is disposed between the'negativelens and said planar electrode for converging the electrons to paths normalto the electrode.
  • Fig.1 isa longitudinal sectional view of one tube em bodying this invention
  • I Fig. 2 is a diagram of the lens system of the tube of-Fig; l'in analogy to geometric optics.
  • Theparticl lar electron discharge device chosen .forv
  • the Iatron type comprising the tubular envelope 1 with the planar phosphor anode 2 across one end of the envelope and the flood gun structu fe 3 at the other end.
  • the writing gun 4 is co centrically disposed at the flood gun-end of the tube.
  • the collector screen 5 and the storage target screen 6 are placed immediately in front of the phosphor anode.
  • An electron charge image is written upon the storage target 6 by the writing gun 4.
  • This charge image in turn modulates the low velocity electron flow from the flood gun 3, in proportion to the local target charge density at any particular point on the storage surface, thus controlling the position and current density of flood electrohsreaching the phosphor screen.
  • the requirement that the flood electrons approach the collector screen and storage target normal to their plane gives rise to the invention.
  • This gun operates at zero (0) voltage on cathode acceleration of the beam to the electrodes primarily accomplished by the collector screen.
  • three focusing electrodes 10, 11 and 12 are disposed concentric with the envelope between the gun and the planar electrodes.
  • the potentials of these three electrodes are positive with respect to the cathode but the potential of the center electrode 11 is lower than the potentials of electrodes 10 and 12 so that in the plane 13 between the first two electrodes is produced a negative electrostatic lens.
  • the relative potentials between electrodes 10 and 11 are so chosen that V the gun beam is sufficiently diverged. With this selection of potentials, accordingly, the electron lens at plane 14 is positive and conveges the electron beam.
  • a second positiveelectron lens is between electrode 12. and the collector screen 5.
  • This second positive lens is in the plane 16.
  • the positive lens at 14 By first initially diverging the beam at lens 13 to a diameter sufficient for obtaining a maximum display size, the positive lens at 14 still has low abberation, because the beam diameter at that lens is small as compared to the lens itself
  • the positive lens at 16 has low aberration, because. its etfective object distance is at 0 thus reducing the angle to X
  • the relative potentials of 10, 11 and 12 are easily adjusted so that the electrons are collimated and approach the planar electrodes 5 and 6 substantially normal to the plane of the electrodes.
  • the tube embodying this invention shown in Fig. 1 comprises the tubular glass envelope 1.
  • the glass plate 2 sealed in one end of the envelope is preferably of optical glass and is internally coated with a transparent film of electroluminescent film such 1 oxide, coated on the gun side of the screen.
  • collector seal ring 15, collector screen 5, and the collector mounting ring carried by the envelope are operated at the highest positive potential within the lens system, for accelerating and focus, :1
  • the writing'gun: 1' A is mounted withbeam acceleratingand focusingelec- Patented Dec. 15, 1959 Closely spaced in front of the phosphor anode is the storage target screen 6 with an electron transmissivity of, say, 30% to 50%, and with a layer of semi-conducting material such as silicon mon- V In front of the storage target 6 k is placed the collector screen 5 of sufficient transmissivity as to not impair the T680111.
  • the flood gun 3 is of the modified Pierce type comprising the cathode sleeve 3a with the dish-shaped coated cathode suriace 35 disposed opposite the conical opening of the gun anodes 3c.
  • the optics of the gun anode and cathode are such that a substantially rectilinear flow of electrons issue from the gun opening.
  • the electrons, after leaving the gun, are subjected to a negative field produced by concentric electrode
  • the angle of divergence can be made sulficiently wide so that the electrons passing through plane 13 are further diverged and are substantially evenly distributed, and yet the divergence is not so great that the beam diameter equals the diameter of the lens thereby avoiding aberration.
  • divergence is quite sensitive to the axial placement of The angle of the gun opening with respectto the neck of the envelope at the gun. That is, the proximity of the electrode 10 to the beam as it emerges fromthe gun is most sensitive to that portion of the electrode which is closest to the gun.
  • Electrodes 11 and 12 are concentric with the envelope and are insulatingly spaced between electrode 10 and collector seal ring 15.
  • the' electrodes 10, 11 and 12' are shownas carbon or aquadag coatings'on the inner surface offthe glass envelope.
  • Metal cylindrical electrodes insulatingly. spaced inthe envelope would be the full electrostatic equivalent.
  • electrodes are; carbon coatings as shown,
  • electrodes 10 and 12 are at about the same voltage, while the potential of electrode 11 is at a voltage below either 10 or 12. While moving from a positivefield to a. field" that is relatively negative, or less positive, across plane 13, the electrons enter a decelerating region and are diverged. While moving across plane 14, however, the electrons enter a relatively, more positive' field'and are converged. Referring to Fig. 2, if the actual cathode is at point 0 and the normal beam angle is x the lens 13*will increase the apparent beam angle represented'by.
  • Electrons at the periphery of lens 14 will be at "point 0 with' the increased beam angle x This will increase spherical aberration if the beam diameter at 14 is large, nearing that of the lens. However, if the beam diameter is 'small, not too much aberration will result at lens 14. Further convergence by .lens 16 will fully collimate the beam withoutaberration due to its efiectively long object distance '0 The total aberration of a multiple-lens system is small if the sum of the aberrationsfrom each lens is -less than'that produced by a simple lens.
  • Fig. 1 One voltage supply for -energizingthe focusing electrode is shown in Fig. 1.
  • the otentiometers aretapped seen and will be refracted as though the cathode "were as shownwith ring 15 and the collector 5 connected to the highest positive potentialt half. thevolta'ge of the ring 15; while “electrode ltlfiis adjusted. by means of potentiometer "2.9 to operate at about one-quarter the ring 15 voltage.
  • the ring 15 and collector screen 5 should be operated in the to 250 volt range.
  • ring 15 was 200 volts, good results were obtained by operating electrode 12 at 100 volts, 10 at 30 volts and 11 at 20 volts. A wide variety of voltage combinations can be found for producing satisfactory results.
  • a planar electrode an electron gun for providing a low velocity floodbeam of electrons, said gun being spaced from the planar electrode on a perpendicular line to the electrode, and a lens system between said gun and said electrode for uniformly flooding the electrode with collimated electrons from said gun including successively a first lens for diverging the electrons, a second .lens for converging the electrons, and a third lens for converging the electrons.
  • a tubular envelope a planar target electrode across one end of the envelope, an elec; tron gun at the other end of the envelope fordirecting; a lowvelocity flood beam of electrons'toward said target electrode; three end-to-end tubular electrodes concentric with the envelope between the gun and planar electrodes, separate lead-in conductors for. each of said tubular electrodes and saidYtarget electrode, a source ofope ratin g potential connected toeach of said lead-in conductors, the source connected to the lead-in conductor of the cen ter" tubular electrode being ata.
  • aplanar'target electrode In combination in a flood gun-typetub, aplanar'target electrode, an electron gun spaced from and Iacingthe target electrode for directing a low -velocit y .flbod beam of electrons toward said target electrode, a negativeelece tron lens and adouble positive electron lensseqiieritially disposed between the gun and planar electrode.

Landscapes

  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US616293A 1956-10-16 1956-10-16 Electron discharge devices Expired - Lifetime US2917658A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE569304D BE569304A (enrdf_load_stackoverflow) 1956-10-16
US616293A US2917658A (en) 1956-10-16 1956-10-16 Electron discharge devices
GB31786/57A GB869814A (en) 1956-10-16 1957-10-11 Improvements in or relating to electronic storage tubes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US616293A US2917658A (en) 1956-10-16 1956-10-16 Electron discharge devices

Publications (1)

Publication Number Publication Date
US2917658A true US2917658A (en) 1959-12-15

Family

ID=24468820

Family Applications (1)

Application Number Title Priority Date Filing Date
US616293A Expired - Lifetime US2917658A (en) 1956-10-16 1956-10-16 Electron discharge devices

Country Status (3)

Country Link
US (1) US2917658A (enrdf_load_stackoverflow)
BE (1) BE569304A (enrdf_load_stackoverflow)
GB (1) GB869814A (enrdf_load_stackoverflow)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2293539A (en) * 1939-08-16 1942-08-18 Bell Telephone Labor Inc Electron discharge device
US2728872A (en) * 1953-10-23 1955-12-27 Hughes Aircraft Co Direct-viewing storage tube with character writing electron gun
US2741724A (en) * 1951-11-27 1956-04-10 Rauland Corp Image-reproducing device
US2790929A (en) * 1954-09-30 1957-04-30 Hughes Aircraft Co Direct-viewing half-tone storage device
US2802966A (en) * 1954-08-06 1957-08-13 Hughes Aircraft Co Direct-viewing electronic storage tubes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2293539A (en) * 1939-08-16 1942-08-18 Bell Telephone Labor Inc Electron discharge device
US2741724A (en) * 1951-11-27 1956-04-10 Rauland Corp Image-reproducing device
US2728872A (en) * 1953-10-23 1955-12-27 Hughes Aircraft Co Direct-viewing storage tube with character writing electron gun
US2802966A (en) * 1954-08-06 1957-08-13 Hughes Aircraft Co Direct-viewing electronic storage tubes
US2790929A (en) * 1954-09-30 1957-04-30 Hughes Aircraft Co Direct-viewing half-tone storage device

Also Published As

Publication number Publication date
BE569304A (enrdf_load_stackoverflow)
GB869814A (en) 1961-06-07

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