US3895250A - Electronic high vacuum tube and method of providing a coating therefor - Google Patents

Electronic high vacuum tube and method of providing a coating therefor Download PDF

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Publication number
US3895250A
US3895250A US341244A US34124473A US3895250A US 3895250 A US3895250 A US 3895250A US 341244 A US341244 A US 341244A US 34124473 A US34124473 A US 34124473A US 3895250 A US3895250 A US 3895250A
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United States
Prior art keywords
high vacuum
coating
tube
vacuum tube
providing
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Expired - Lifetime
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US341244A
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English (en)
Inventor
Hermann Christgau
Karl Franz
Jurgen Niepel
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Siemens AG
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Siemens AG
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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
    • H01J31/50—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output
    • H01J31/501—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output with an electrostatic electron optic system

Definitions

  • An electronic high vacuum tube has a high vacuum container containing two conducting parts of different electrical potentials which produce between these parts high electrical field strength.
  • the invention is particularly characterized in that at least the part which lies upon the high potential has upon its outer surface an electrically insulating layer which binds alkali metals. This coating is produced by immersing the part to be coated into a bath consisting of a solution of partially condensed polyimides followed by special treatment.
  • Tubes of this type are, for example, electronically optical image amplifiers wherein electrodes subjected to high voltage produce an image of released electrons upon a sheet-like photocathode.
  • they can be also used in other high vacuum tubes to eliminate unde sired effects, since no secondary electrons are released.
  • the quality of electronic image amplifiers is determined primarily by the amplifying factor and the properties with which the images are transmitted. A measure for these properties is the visually measured analysis and the modulation transmission function which provides contrast transmission depending upon the size of details. Since electronic optical image transforming tubes and image amplifiers carry voltages of to 35 kv for electronic optical magnification, disturbing field emissions can take place. In order to avoid them as much as possible, the surfaces of the voltage carrying parts, such as grids, actuating electrodes etc., are made very flat. For exam ple, the surfaces are smoothed to such an extent that all unevenesses amounting to more than 1 ,u. m disappear. Despite this smoothing electronic emissions or spontaneous flashovers take place.
  • the undesired effects consist primarily in that the flashovers or other discharges are followed by appearance of light which acts upon the emission layer of the photocathode and releases electrons. These electrons produce intensive light appearances upon the viewing screen and disturb considerably the image reproducing properties of the tube.
  • An object of the present invention is to eliminate to the greatest extent the release of electrons by electrodes which are subject to voltage and by current carrying parts.
  • a simple reason for the detrimental effects can lie in the manufacture of the photocathode.
  • antimony and caesium, or several alkali metals are steamed on in the tube upon a carrier.
  • Alkali metals particularly caesium are unavoidably spread over surfaces of other parts of the tube.
  • the work function of electrons is diminished to the work function of electrons on surfaces of alkali metals.
  • the coating of the present invention acts against the diminution.
  • the greatest voltage difference is located as a rule between the third electrode and the following anode.
  • the layer of an organic substance applied upon this electrode prevents discharges in that the outer surface is smoothed, thereby diminishing in the known manner the outflow of electrons.
  • the alkali metals used in the manufacture of photocathodes are bound by the organic substances, thereby preventing the outgoing of the electrons at the outer surface.
  • vacuum fixed substances were found to be organic substances, such as thin layers of polyimide. They consist of condensation products of organic acids, for example, pyromelilotic acid or maleic acid with amines, for example, I, 4 -diaminobinzol. These layers bind alkalimetal gases and consequently those of caesium, which appear during the making of the photocathode by a mechanism wherein side bindings are acceptable or in the form of fixed solutions.
  • high fluorated hydrocarbons such as, for example, polytetrafluorethylene, polysulfon, particularly polyarylsulfon, and also silicon resin, also cause the binding of alkali metals. This has the property of binding alkali metal gases, for example, by a substitution, whereby the freed hydrogen is removed during the evacuation of the tube.
  • FIGURE shows by way of example only, a section through an Xray image amplifier constructed in accordance with the present invention.
  • the drawing shows an amplifier having electrodes 1, 2 and 3 located between the cathode 4 and the anode 5 behind the inlet window 6 of a high vacuum tube 7 consisting of glass.
  • the photocathode consists of a carrier 8, a luminous layer 9 and the actual photocathode layer 10.
  • the anode 5 is closed by the luminous layer 11 located in front of the end window 12 of the tube.
  • the cathode is connected by a line 13 to the ground potential of current supply ing means (not shown).
  • the connection 14 of the electrode 1 is subjected to v., the connection 15 of the electrode 2 to a potential of 300 v., the connection 16 of the electrode 3 to a potential of 3.5 kv., and the connection 17 of the anode to a potential of 25 kv.
  • the coating of the present invention is applied to the electrode 3 and is indicated as 18. It consists of polyimide and is applied by a process described hereinbelow.
  • an X-ray quantum passes in the known manner through the ray inlet window and the carrier 10 and strikes the luminous layer 9, it produces there a luminous action which releases electrons in the photocathode layer 10.
  • These electrons are actuated by the potentials located at the electrodes 1, 2 and 3 and the anode 5 and are directed to the luminous layer 11. They receive the greatest acceleration in the range of electrode 3 and can produce there at the outer surfaces electrons which do not come from the photocathode and which cause appearances releasing additional electrons at the photocathode. These would produce on the screen 11 representations which are not released by the X-rays.
  • This is prevented by the coating 18 which cov ers the outer surface of the electrode 3.
  • the coating has a thickness of 5 ,u m and it prevents the release of an uncontrollable amount of electrons.
  • the method of making the polyimide layer is as follows:
  • the inner ring is inserted with its bent edge extending downwardly into a bath containing a solution of partly condensed polyimide dissolved in a diluter, as, for ex ample, dimetylformamide. It was found advantageous to use twice as much of the diluter as of the partial condensate, since then the solution at room temperature .3 has useable own viscosity.
  • the amount of liquid in the bath can be used to determine the duration of the application of coating upon the electrode 3.
  • the ring is removed from the bath. is mounted upon a holding device to remove the excessive drops and is dried while being rotated by an infrared radiator. After the resin during drying has reached a viscosity wherein the layer does not run any more, the lacquer film is heated in a warming cabinet in air for l hour at lOOc and thereupon for 2 hours at 300C.
  • An electronic high vacuum tube comprising a high vacuum container, two conducting members located within said container, means connected with said members and providing them with different electrical potentials which produce high electrical field strength between said members, and an electrically insulating coating carried by at least the member having a higher potential, said coating binding alkali metals and consisting of a compound selected from the group consisting of polytetrafluorethylene, polysulfon, polyarylsulfon and silicon resin.

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  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US341244A 1972-03-20 1973-03-14 Electronic high vacuum tube and method of providing a coating therefor Expired - Lifetime US3895250A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2213493A DE2213493C3 (de) 1972-03-20 1972-03-20 Elektronische Bildverstärkerröhre, bei der ein elektrisch leitendes TeU mit einer elektrisch isolierenden Schicht versehen ist, und Verfahren zur Herstellung dieser Schicht

Publications (1)

Publication Number Publication Date
US3895250A true US3895250A (en) 1975-07-15

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US341244A Expired - Lifetime US3895250A (en) 1972-03-20 1973-03-14 Electronic high vacuum tube and method of providing a coating therefor

Country Status (4)

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US (1) US3895250A (fr)
JP (1) JPS5612990B2 (fr)
DE (1) DE2213493C3 (fr)
FR (1) FR2176850B1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4053855A (en) * 1975-10-28 1977-10-11 International Telephone And Telegraph Corporation Method and arrangement to eliminate multipacting in RF devices
US5012152A (en) * 1989-01-09 1991-04-30 U.S. Philips Corp. Image intensifier tube comprising coated electrodes
US5091639A (en) * 1990-03-06 1992-02-25 Siemens Aktiengesellschaft Mount for an electrode system in an x-ray image intensifier
US6175612B1 (en) * 1998-02-03 2001-01-16 Seiko Instruments Inc. In-line fluorescent x-ray film thickness monitor

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61175356U (fr) * 1985-04-20 1986-10-31
FR2600177B1 (fr) * 1986-06-13 1988-08-19 Thomson Csf Procede de fabrication d'un intensificateur d'images radiologiques et intensificateur d'images radiologiques ainsi obtenu
JP2817958B2 (ja) * 1988-09-02 1998-10-30 シンシナティ・ミラクロン‐ヒールド・コーポレーション 研削工程を制御するための改良された装置と方法、および砥石を修正するための装置と方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2666864A (en) * 1950-01-20 1954-01-19 Westinghouse Electric Corp Image intensifier tube
US2879406A (en) * 1955-05-31 1959-03-24 Westinghouse Electric Corp Electron discharge tube structure

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2666864A (en) * 1950-01-20 1954-01-19 Westinghouse Electric Corp Image intensifier tube
US2879406A (en) * 1955-05-31 1959-03-24 Westinghouse Electric Corp Electron discharge tube structure

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4053855A (en) * 1975-10-28 1977-10-11 International Telephone And Telegraph Corporation Method and arrangement to eliminate multipacting in RF devices
US5012152A (en) * 1989-01-09 1991-04-30 U.S. Philips Corp. Image intensifier tube comprising coated electrodes
US5091639A (en) * 1990-03-06 1992-02-25 Siemens Aktiengesellschaft Mount for an electrode system in an x-ray image intensifier
US6175612B1 (en) * 1998-02-03 2001-01-16 Seiko Instruments Inc. In-line fluorescent x-ray film thickness monitor

Also Published As

Publication number Publication date
DE2213493C3 (de) 1980-02-28
FR2176850A1 (fr) 1973-11-02
JPS496875A (fr) 1974-01-22
DE2213493A1 (de) 1973-10-04
FR2176850B1 (fr) 1978-05-12
JPS5612990B2 (fr) 1981-03-25
DE2213493B2 (de) 1979-06-28

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