US3144578A - Symbol displaying electron discharge tubes unsing secondary emission - Google Patents

Symbol displaying electron discharge tubes unsing secondary emission Download PDF

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Publication number
US3144578A
US3144578A US110250A US11025061A US3144578A US 3144578 A US3144578 A US 3144578A US 110250 A US110250 A US 110250A US 11025061 A US11025061 A US 11025061A US 3144578 A US3144578 A US 3144578A
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US
United States
Prior art keywords
symbol
electrodes
electrode
screen
secondary emission
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
US110250A
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English (en)
Inventor
Sinclair Ian Robertson
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.)
Teledyne UK Ltd
Original Assignee
English Electric Valve Co Ltd
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 English Electric Valve Co Ltd filed Critical English Electric Valve Co Ltd
Application granted granted Critical
Publication of US3144578A publication Critical patent/US3144578A/en
Anticipated expiration legal-status Critical
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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
    • H01J31/16—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen with mask carrying a number of selectively displayable signs, e.g. charactron, numeroscope

Definitions

  • a symbol displaying electron discharge tube comprises within an evacuated envelope, a fluorescent screen; an electron gun adapted to provide an electron beam to flood said screen substantially uniformly with electrons; and, in the path of the beam to said screen, two spaced mesh electrodes extending transversely across said path and having between them a plurality of transversely arranged symbol electrodes, insulated from one another and each having its own connection electrode leading to the outside of the envelope, each symbol electrode being shaped in accordance with a desired symbol to be displayed and each being provided on the side thereof facing the gun with a layer of insulating material having a relatively high co-efiicient of secondary emission and a relatively low first secondary emission cross-over.
  • insulating materials which are suitable for use as layers on the symbol electrodes of a tube in accordance with this invention, examples of preferred materials being magnesium fluoride, magnesium oxide and tale.
  • the symbol electrodes may conveniently be made of wires bent into the required shapes, e.g., the shapes of letters or numerals.
  • a tube comprises an electron gun having a control grid electrode and positioned at or near one end of the envelope; an accelerator electrode adjacent said gun; a fluorescent screen at or near the other end of the envelope; two spaced mesh electrodes which are electrically connected together and are substantially parallel to said screen; a plurality of symbol electrodes between said mesh electrodes and substantially parallel thereto, each having a layer of insulating material on the side theroef towards the gun; and, between the accelerator electrode and the mesh electrode nearer thereto, a collimator electrode adapted to collimate into substantially parallel paths, the electrons of a beam of electrons projected from said gun past the mesh and symbol electrodes to the screen.
  • control grid and collimator electrodes are operated at such potentials in relation to one another and to the potentials applied to the other electrodes of the tube as to collimate the beam before it reaches the first mesh electrode in its path;
  • the mesh electrodes are operated at a potential which is positive in relation to the gun cathode;
  • the symbol electrodes are operated (when it is not desired to display any symbol) at a potential a little below the first crossover potential of the secondary emitting insulating material thereon;
  • the fluorescent screen is operated at a potential which is not negative with respect to the mesh electrode potential and is pie ferably substantially positive with respect thereto.
  • the gun cathode If, with the applied potentials as just described, the gun cathode is pulsed negatively, the electrons of the beam will strike the layers of secondary emitting material on the symbol electrodes at such velocity as to cause them to 3,li4,578 Patented Aug. 11, 1964 charge up to the potential of the nearest secondary electron collector electrode, i.e., a mesh electrode. In this condition the symbol electrodes cause minimum interference with the beam and the screen will be substantially uniformly illuminated.
  • one particular symbol electrode is brought to a sufiicient negative potentialas, for example, by applying a pulse of sufllciently negative potential to the selected symbol electrode-so that it is driven to a potential well below that of the first secondary emission cross-over of the insulating layer material thereon, the said layer will assume the gun cathode potential by process of cathode potential stabilisation of an insulator. In this condition the electrons of the beam will be repelled from the region of the particular symbol electrode chosen and that symbol will be displayed as a shadow on the screen. Any symbol thus displayed can be erased by pulsing the cathode negatively and another symbol can then be chosen for display.
  • the tube therein shown has a bulbous glass envelope 1 with an electron gun having a cathode 2 and a control grid electrode 3 in the neck end.
  • an ordinary fluorescent or phosphor screen 4 On or near the large transparent end wall of the envelope is an ordinary fluorescent or phosphor screen 4.
  • the external connection to the screen is shown at 5.
  • Parallel to one another and to the screen are two mesh electrodes 6 and 7 extending right across the tube and connected electrically to one another and to an external connection 8.
  • Between the meshes 6 and 7 is a plurality of symbol electrodes 9 shaped in accordance with desired different symbols and each made of wire with a coating of insulating material, such for example, as magnesium fluoride, on the side thereof towards the mesh 6 and the gun.
  • Adjacent the gun is an accelerator electrode 11 and between this and the first mesh 6 is a collimator electrode 12.
  • the cathode 2 may be at earth potential or the control electrode 3 at a negative potential sufiicient to e11- sure collimation of the beam before entry to the mesh 6 if the other operating potentials are suitably chosen.
  • the meshes 5 and 7 may be operated at, say, vol-ts and the symbol electrodes at a normal potential (lie, when no symbol is required to be displayed) just below the first secondary emission cross-over potential of the insulating material thereon which potential may, in a practical case, be about 50 volts.
  • the operating potential of the screen may be about 500 volts.
  • a symbol displaying electron discharge tube comprising within an evacuated envelope, a fluorescent screen; an electron gun adapted to provide an electron beam to flood said screen substantially uniformly with electrons; and, in the path of the beam projected to said screen, two spaced apart mesh electrodes extending transversely across said path and a plurality of transversely arranged symbol electrodes disposed between said mesh electrodes, said symbol electrodes being insulated from one another and each having its own connection electrode leading to the outside of the envelope, each symbol electrode being shaped in accordance with a desired symbol to be displayed and each being provided on the side thereof facing the gun with a layer of insulating material having a relatively high coeflicient of secondary emission and a relatively low first secondary emission cross-over potential.
  • a symbol displaying electron discharge tube comprising within an evacuated envelope, a fluorescent screen; an electron gun projecting an electron beam toward said screen to flood the screen substantially uniformly with electrons, said gun including a control grid electrode and a cathode; first and second spaced apart mesh electrodes positioned to intersect the projected electron beam; a plurality of transversely arranged symbol electrodes disposed between said mesh electrodes, said symbol electrodes being insulated from one another and each having its own connection electrode leading to the outside of the envelope, each symbol electrode being shaped in accordance with a desired symbol to be displayed and each being provided on the side thereof facing said gun with a layer of insulating material having a relatively high coefiicient of secondary emission and a relatively low first secondary emission cross-over potential; 21 collimator electrode for colli-mating the electrons of said beam into substantially parallel paths; means for applying to said cathode, said control grid electrode, and said collimator electrode operating potentials which collimate said beam before it reaches said first mesh electrode; means for applying to both mesh electrode

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Gas-Filled Discharge Tubes (AREA)
US110250A 1960-05-16 1961-05-15 Symbol displaying electron discharge tubes unsing secondary emission Expired - Lifetime US3144578A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB17129/60A GB913963A (en) 1960-05-16 1960-05-16 Improvements in or relating to symbol displaying electron discharge tubes

Publications (1)

Publication Number Publication Date
US3144578A true US3144578A (en) 1964-08-11

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Family Applications (1)

Application Number Title Priority Date Filing Date
US110250A Expired - Lifetime US3144578A (en) 1960-05-16 1961-05-15 Symbol displaying electron discharge tubes unsing secondary emission

Country Status (3)

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US (1) US3144578A (enrdf_load_html_response)
GB (1) GB913963A (enrdf_load_html_response)
NL (1) NL264779A (enrdf_load_html_response)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2031219B (en) * 1978-10-04 1982-12-01 English Electric Valve Co Ltd Crt matrix display
GB2124825B (en) * 1982-08-06 1986-03-26 English Electric Valve Co Ltd Cathodoluminescent display arrangements

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2927237A (en) * 1940-07-23 1960-03-01 Int Standard Electric Corp Voltage indicator tubes
US2964672A (en) * 1958-07-22 1960-12-13 Gen Electric Co Ltd Cathode ray display devices
US3005922A (en) * 1959-11-13 1961-10-24 Nat Union Electric Corp Luminous discharge indicia tube

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2927237A (en) * 1940-07-23 1960-03-01 Int Standard Electric Corp Voltage indicator tubes
US2964672A (en) * 1958-07-22 1960-12-13 Gen Electric Co Ltd Cathode ray display devices
US3005922A (en) * 1959-11-13 1961-10-24 Nat Union Electric Corp Luminous discharge indicia tube

Also Published As

Publication number Publication date
GB913963A (en) 1962-12-28
NL264779A (enrdf_load_html_response)

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