US2186393A - Fluorescent screen - Google Patents

Fluorescent screen Download PDF

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Publication number
US2186393A
US2186393A US189010A US18901037A US2186393A US 2186393 A US2186393 A US 2186393A US 189010 A US189010 A US 189010A US 18901037 A US18901037 A US 18901037A US 2186393 A US2186393 A US 2186393A
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United States
Prior art keywords
screen
potential
electrons
cathode
wires
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Expired - Lifetime
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US189010A
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English (en)
Inventor
Ring Friedrich
Weizs Georg
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Individual
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Individual
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    • 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

Definitions

  • the invention relates to fluorescent screens and .to cathode. ray' tubes containing such screens. It is particularly concemed with screens for making visible pictures or drawings of any kind, for instance lines, diagrams ⁇ and letters.
  • the ar rangement according to the invention is especially adapted to produce bright television images with changing contents, advertising pictures in black and white only or oscillograms. 4
  • Flg. 1 is a sectional 'view of a cathode ray cording to the invention. i
  • Figs. 2 and 3 are dia explaining the operation of the tube represented in Flg. l.
  • Flg. e is a cross section through a screen structure according to the invention on an enlarged scale and u Fig. is a plan 'view of a part of the screen structure of Flg. 4.
  • the tube of Flg. 1 contains within an envelope i a screen 2 of insulating material with a layer of fiuorescent material 8.
  • a grid electrode 4 is arranged in front of the screen and connected. by a lead 5 to the outside.
  • the tube contains furthermore a cathode 9 having for instance the form of a wire. spiral bent to form a ring and connected by conductors and 8 to a heating battery 9.
  • the tube contains furthermore a cathode ID of oonventional type for producing a cath- 6' ode ray and connected to a battery l I.
  • 2 is arranged in front of the cathode !0. This electrode has the form of the wellknown Wehnelt cylinder.
  • Externally of the tube j a concentrating coil
  • Two deflectlng' systems M and I 5 are indicated schematically and constructed in accordance with the usual practice of oscillographs and television tubes.
  • a potential of +500 V. is applied togrid 4 with respect to the potential of cathode 6 a's zero-potential.
  • Cathode !0 has a potential of -1000 V. against cathode 6.
  • 2 and concentrated by coii M is deflected over the screen 2 so that a local potential distribution is produced and stored on the screen in such a manner that certain portions of the screen have a potential lying above a value of for instance 250 V. against cathode 8 and the remaining portions have a potential below 250 V.
  • the whole screen is sprayed diflusely and uniformly with electrons. These electrons are accelerated to a velocity of 500 V. by the grid 4 40 but they reach the fluorescent layer with a velocity depending upon the potential of the respective surface element of the screen.
  • An element having a potential above 250 V. is bombarded by electrons of high velocity 'and more u secondary electrons' are liberated than primary eiectronsreach this element. ⁇
  • the potential of the element is made more positive by the loss of. electrons and this increase of potential is con tinued until the potential of grid I is reached.
  • the screen having a potential lower than 250 V. is reached by electrons .having a comparatively low velocity and the number of secondary electrons is smaller than the u ordinate 1 gives'the ratio of the number of secondary electrons to the number of primary electrons the abscissa indicates the velocity of the imameting electrons in Volts.
  • Fluorescent materials as ordinarily used in cathode ray tubes for instance zine sulde have ai characteristic cui-ve Oi reaching the value of I at 250 V.
  • the critical value of 250 V. depends upon the material of the fluorescent layer and its treatment and can be changed in fairly wide limits by the correct selection of the material. It is 'also possible to change the potential on grid 3 and cathode i@ in wide limits. Experiments have shown, that it is possible to maintain luminating and dark portions on the screen adjacent to one another also in case the base of the screen consists of a metal plate. The insulating properties of the fiuorescent material are sufliciently good to build up local charges on the screen.
  • the fiuorescent material !9 is arranged upon the'insulating support 8 and bombarded by electrons in the direction of arrows 20. It is assumed that the fluorescentmaterial has the potential on the right hand side of the figure as' far as it isrepresented black and has a potential of 500 V. in the left hand part. The distribution of the potential is indicated by curve Zi showing the potential in dependence from the local extension of the screen. A large difference of poten'tials ex sts at the place of arrow 22 and the slope of the local diflerence in potential depends upon the conductivity of the material.
  • the velocity of the diflusely emitted electrons is exactly adjusted in such a manner that neither a displacement in one or the other direction occurs.
  • a voltage of about 500 V. has been found as critical for a stationary picture. It'can be assumed that the critical value of the material of corresponds to about half this voltage, i. e. to'
  • a second concentrated cathode ray may be used for cancelling the pictures; this ray is defiected in a similar manner as the recording pencil but is displaced a few lines in advance of the recording pencil. It is also advantageous to divide the screen and/or the grid in front of the screen into a number of sections parallel to the lines of the picture. The cancellation is eil'ected in one section only of the screen at a time shortly before the recording The direction and' It is prefercathode ray is touching this part of the screen.
  • FIG. 4 shows the screen of a tube similar to that of Fig. 1 with two cathodes.
  • the screen is rep'esented on an enlarged scale and consists of a number of parallel wires 23 insulated from one another.
  • the wires are partly embedded in the insulating material 24 and are covered with fluorescent material 25.
  • the fluorescent material is covering also the exposed surface oi' the insulating material 24.
  • Fig. 5 shows a View of the screen from the side of the cathode.
  • the wires 23 are bent upwardly on the right hand side and are terminating in or upon the insulating material forming the carrier, of the screen.
  • a conductor 24 is arranged at the edge of the screen.
  • a conductor 24 is arranged at the edge of the scren.
  • the strip of material 25 between the conductor 24 and the ends of wires 23 is semi-conducting so that all the wires 23 are connected by way of this resistance with a source of potential of 500 V.
  • the surface of the wires is carefully cleaned between the dotted lines 26 and 21 and a strip of finely divided carbon, for instance graphite, is applied. Furthermore each pair of adjacent wires -is connected by conductingi bridges 28.
  • the quick decrease of potential of the wires serves to cancel the illumination in that part of the screen lying near thewires.
  • the screen is therefore brought to darkness a few lines in advance of the cathocle ray.
  • the cathode ray is then quickly re.- turned and writes the second line as indicated by arrow 38.
  • the return movement it touches the sections 2 s of wires which are more closely adjacent to its next path, so that these wires are made more positive thereby.
  • the wires brought i quickly to a lower potential are slowly made more positive by the current flowing through the semiconductor 25, so that the wires assume again the function of grid 4 of Fig. 1, the lumination near these wires being however cancelled.
  • a screen of this type may contain separate cancelling and accelerating electrodes. It is also possible to divide the fiuorescent material into single insulated elements by cutting lines into the layer or by spraying the fluorescent material through a' grid which is removed afterwards. Such a. screen consisting of insulated fiuorescent particles has the advantage that the displacement efiect described in connection with Fig. 3 is minimsed.
  • the elements of the screen are luminating either brightly or not at all the pictures are only black and white without half-tones' It is however possible to obtain half-tone-pictures by changing the width of the luminating lines.
  • the modulated ray m is therefore controlled in such a manner that chiefly the diameter or size of the spot is changed while the intensity of the ray per surface unity is kept approximately constant.
  • the visibility of the lines can be decreased by using an interlaced scanning method.
  • a material* is used for the screen in which the value is reached above 500 V. or more.
  • the efiect of the cancelling strip 26, El may be increased .by ⁇ multiplying the effect of decreasing the potential by a multistage secondary emisslon multiplier for instance of the grid type.
  • the potential distribution maintained on the screen can also be used for controlling 'other effects. It is also within the scope of the invention to produce an electron optical image of the screen surface upon another surface and to sepa- 'rate locally the production-of the potential distribution and the luminous efifect.
  • a cathode ray tube an insulating plate, a fluorescent screen on said plate, a source of electrons for suitormly bombarding the whole area of said screen with'electrons, an accelerating electrode in front of said screen having a fixed potential above the critical value at which the number of secondary electrons emitted by the screen exceeds the number of primary electrons,
  • a cathode ray tube a plate, fluorescent insulated elemental areas on said plate, a source of electrons for uniformly bombardng the whole area of said plate with electrons, an accelerating electrode having a fixed potential of twice the critical value at which the number of secondary electrons emitted by the plate exceeds the number of primary electrons, and means' for charging elementa areas of said plate to diflerent potenv tials.

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  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US189010A 1936-10-26 1937-12-15 Fluorescent screen Expired - Lifetime US2186393A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE204095X 1936-10-26

Publications (1)

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US2186393A true US2186393A (en) 1940-01-09

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Application Number Title Priority Date Filing Date
US189010A Expired - Lifetime US2186393A (en) 1936-10-26 1937-12-15 Fluorescent screen

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US (1) US2186393A (en:Method)
CH (1) CH204095A (en:Method)
NL (1) NL53011C (en:Method)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2618762A (en) * 1945-04-12 1952-11-18 Rca Corp Target and circuit for storage tubes
US2618763A (en) * 1945-04-12 1952-11-18 Rca Corp Target for storage tubes of the cathode beam type
US2680204A (en) * 1950-11-30 1954-06-01 Rca Corp Gun structure
US2685661A (en) * 1951-09-25 1954-08-03 Rca Corp Cathode-ray beam deflection
US2705764A (en) * 1950-02-25 1955-04-05 Rca Corp Dual-area target electrodes and methods of making the same
US2771504A (en) * 1951-12-11 1956-11-20 Philco Corp Color television indexing system
US2790929A (en) * 1954-09-30 1957-04-30 Hughes Aircraft Co Direct-viewing half-tone storage device
US2811666A (en) * 1950-02-16 1957-10-29 Nat Res Dev Electronic information storing devices
US2818524A (en) * 1956-10-02 1957-12-31 Hughes Aircraft Co Multi-color storage tube
US2824259A (en) * 1955-06-06 1958-02-18 Hughes Aircraft Co Virtual flood-electron source
US2890376A (en) * 1954-07-20 1959-06-09 Philips Corp Image producing discharge device
US2967971A (en) * 1957-08-14 1961-01-10 Hughes Aircraft Co Storage tube with improved flood gun
US3366836A (en) * 1952-08-28 1968-01-30 Sylvania Electric Prod Visual display device
US4801850A (en) * 1987-07-28 1989-01-31 Xerox Corporation High brightness vacuum fluorescent display (VFD) devices

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2618763A (en) * 1945-04-12 1952-11-18 Rca Corp Target for storage tubes of the cathode beam type
US2618762A (en) * 1945-04-12 1952-11-18 Rca Corp Target and circuit for storage tubes
US2811666A (en) * 1950-02-16 1957-10-29 Nat Res Dev Electronic information storing devices
US2705764A (en) * 1950-02-25 1955-04-05 Rca Corp Dual-area target electrodes and methods of making the same
US2680204A (en) * 1950-11-30 1954-06-01 Rca Corp Gun structure
US2685661A (en) * 1951-09-25 1954-08-03 Rca Corp Cathode-ray beam deflection
US2771504A (en) * 1951-12-11 1956-11-20 Philco Corp Color television indexing system
US3366836A (en) * 1952-08-28 1968-01-30 Sylvania Electric Prod Visual display device
US2890376A (en) * 1954-07-20 1959-06-09 Philips Corp Image producing discharge device
US2790929A (en) * 1954-09-30 1957-04-30 Hughes Aircraft Co Direct-viewing half-tone storage device
US2824259A (en) * 1955-06-06 1958-02-18 Hughes Aircraft Co Virtual flood-electron source
US2818524A (en) * 1956-10-02 1957-12-31 Hughes Aircraft Co Multi-color storage tube
US2967971A (en) * 1957-08-14 1961-01-10 Hughes Aircraft Co Storage tube with improved flood gun
US4801850A (en) * 1987-07-28 1989-01-31 Xerox Corporation High brightness vacuum fluorescent display (VFD) devices

Also Published As

Publication number Publication date
NL53011C (en:Method)
CH204095A (de) 1939-04-15

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