US3666547A - Photo-cathodes for electronic discharge tubes - Google Patents

Photo-cathodes for electronic discharge tubes Download PDF

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Publication number
US3666547A
US3666547A US23785A US3666547DA US3666547A US 3666547 A US3666547 A US 3666547A US 23785 A US23785 A US 23785A US 3666547D A US3666547D A US 3666547DA US 3666547 A US3666547 A US 3666547A
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US
United States
Prior art keywords
photo
antimony
photocathode
cathodes
temperature
Prior art date
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Expired - Lifetime
Application number
US23785A
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English (en)
Inventor
Thomas Murphy
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US Philips Corp
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US Philips Corp
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Publication date
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Publication of US3666547A publication Critical patent/US3666547A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/12—Manufacture of electrodes or electrode systems of photo-emissive cathodes; of secondary-emission electrodes

Definitions

  • This invention relates to photo-emissive cathodes for electric discharge tubes and to the manufacture of tubes containing such photocathodes.
  • Examples of such tubes are imaging tubes and photo-multiplier tubes, and antimony is a typical example of photo-cathode material for such tubes.
  • the present invention provides a method of manufacturing an electric discharge tube containing a photocathode which method includes a high temperature vacuum baking step, a preceding step in which the source of photo-cathode material is coated with a sealant which is inert to the photo-cathode material to suppress or minimise evaporation of said photo-cathode material during said baking step, and a subsequent photo-cathode forming step in which said source of photo-cathode material is raised to a temperature higher than that of the preceding baking step.
  • the photo-cathode material is constituted at least principally by antimony.
  • the sealant may be a silicate, for example potassium silicate, soda metasilicate or ethyl silicate.
  • potassium silicate has been used on an antimony head.
  • the photocathodes formed from such beads have been found to be unaffected by the coating, and indeed such good photocathodes have been made as to suggest that the coating may be beneficial in preventing contamination of the antimony during the bake-out process.
  • the coating may prevent contamination (e.g. by oxidation) while the head is stored before baking, such storage being done in air at a temperature of, say, C. to keep the components dry (actually the coating can thus protect the bead in air even at higher temperatures up to about 300 C.).
  • FIG. 1 being an axial section
  • FIG. 2 an end view
  • FIG. 3 a side view.
  • the two connections A-B are of molybdenum wire, e.g. 0.1 mm. thick, having a cranked section on which the antimony bead C is formed.
  • the wire is coated with platinum which has afiinity for the antimony.
  • the head C is about 1 mm. in diameter and has a coating D of potassium silicate I to 5 thick which covers also the spread of antimony (at E) on either side of the bead proper.
  • the head When manufacturing a tube with the aid of such a head, the head is located in an appropriate position inside the tube envelope with the wires A-B connected to external terminals which are provided on the envelope.
  • the tube is then evacuated and baked (e.g. up to, say, 400 C.) without the silicate coating breaking down or allowing escape of antimony.
  • the photocathode is formed by passing a heavy current pulse through the A-B connections so as to raise the bead to a temperature much higher than 400 C. thereby evaporating the antimony onto the desired surface or surfaces, such evaporating being directed thereto e.g. by a shield or shields in known manner.
  • a method of manufacturing an electric discharge tube having a photocathode comprising the steps of placing a source of photo-cathode material coated with a sealant inert to the photo-cathode material within an evacuated envelope, heating the envelope with the source of photo-cathode material therein to a temperature at which the envelope is baked without breaking down to the sealant coating the source of photo-cathode material, and thereafter raising the temperature to form the photocathode.
  • sealant is a silicate
  • sealant is potassium silicate.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US23785A 1969-03-31 1970-03-30 Photo-cathodes for electronic discharge tubes Expired - Lifetime US3666547A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB06735/69A GB1298362A (en) 1969-03-31 1969-03-31 Improvements relating to electric discharge tubes comprising photo-cathodes

Publications (1)

Publication Number Publication Date
US3666547A true US3666547A (en) 1972-05-30

Family

ID=10082717

Family Applications (1)

Application Number Title Priority Date Filing Date
US23785A Expired - Lifetime US3666547A (en) 1969-03-31 1970-03-30 Photo-cathodes for electronic discharge tubes

Country Status (4)

Country Link
US (1) US3666547A (OSRAM)
DE (1) DE2015995A1 (OSRAM)
FR (1) FR2040146A5 (OSRAM)
GB (1) GB1298362A (OSRAM)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4225881A (en) * 1978-11-27 1980-09-30 Murray Tovi Designs, Inc. Discrete surveillance system and method for making a component thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3712700A (en) * 1971-01-18 1973-01-23 Rca Corp Method of making an electron emitter device
DE10037729A1 (de) * 2000-08-02 2002-02-21 Henkel Kgaa Mikrokapsel, Verfahren zu deren Herstellung und deren Verwendung in Klebstoffen

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4225881A (en) * 1978-11-27 1980-09-30 Murray Tovi Designs, Inc. Discrete surveillance system and method for making a component thereof

Also Published As

Publication number Publication date
GB1298362A (en) 1972-11-29
DE2015995A1 (de) 1970-10-08
FR2040146A5 (OSRAM) 1971-01-15

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