US2967962A - Television and like camera tubes - Google Patents

Television and like camera tubes Download PDF

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Publication number
US2967962A
US2967962A US769252A US76925258A US2967962A US 2967962 A US2967962 A US 2967962A US 769252 A US769252 A US 769252A US 76925258 A US76925258 A US 76925258A US 2967962 A US2967962 A US 2967962A
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US
United States
Prior art keywords
mesh
antimony
coating
photo
layer
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
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US769252A
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English (en)
Inventor
Turk Walter Ernest
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
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Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/39—Charge-storage screens
    • H01J29/45—Charge-storage screens exhibiting internal electric effects caused by electromagnetic radiation, e.g. photoconductive screen, photodielectric screen, photovoltaic screen
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/38—Photoelectric screens; Charge-storage screens not using charge storage, e.g. photo-emissive screen, extended cathode
    • 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
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/233—Manufacture of photoelectric screens or charge-storage screens

Definitions

  • This invention relates to television and like camera tubes and more specifically to such tubes of the kind in which there is a field-terminating mesh grid fairly close to the picture receiving photo-cathode of the tube.
  • a very well known camera tube of this kind is the socalled Vidicon tube.
  • the photocathode is formed on the inside of the end wall of the envelope and, fairly close to and parallel to the said photo-cathode, is a mesh or grid which lies transversely across the otherwise open end of the tubular metal focusing electrode system.
  • the photo-cathode on the inside of the end wall of the tube is usually formed in two stages as follows: Firstand after a transparent signal plate layer (usually of tin oxide) has been deposited on the glassa crucible containing antimony trisulphide with from 2% to 6% excess antimony is introduced through a branch pipe on the envelope so as to lie inside the tubular metal focusing electrode system and the crucible is electrically heated to evaporate its contents and deposit the evaporated material through the mesh on to the end wall, i.e. onto the signal plate layer.
  • a transparent signal plate layer usually of tin oxide
  • antimony trisulphide with from 2% to 6% excess antimony is introduced through a branch pipe on the envelope so as to lie inside the tubular metal focusing electrode system and the crucible is electrically heated to evaporate its contents and deposit the evaporated material through the mesh on to the end wall, i.e. onto the signal plate layer.
  • This evaporation step is performed in the presence of an inert gas, usually argon, and results in the deposition of a porous or somewhat spongy layer on the end wall. It also results in a similar deposit on the mesh itself and since this deposit is (in the absence of light irradiation) insulating it must be removed. Accordingly the crucible is now removed, the envelope is pumped out to a hard vacuum and eddy current heating is applied to the mesh to evaporate the deposit thereon. This second evaporation step forms a second deposit on the end wall, this time of a compact substantially non-porous nature.
  • an inert gas usually argon
  • the mesh or grid of a camera tube of the kind referred to is initially coated
  • the metal is antimony.
  • initially coated is meant that the coating is applied to the mesh before the evaporation steps by which the photo-cathode is deposited on the end wall of the tube.
  • a process of making a photo-cathode in a camera tube of the kind referred to comprises the steps of initially coating the mesh with a metal of low light reflecting quality (preferably antimony) either directly or upon an intermediate metal layer, evaporating antimony trisulphide through said mesh in the presence of an inert gas to form a porous cathode layer and then evaporating 2,957,962 Patented Jan. 10, 1961 has shown that, in fact, the result of providing this in-' itial coating is to leave the mesh, after the said evaporation step, dark and of poor light reflecting qualities despite that one would expect the said step of evaporation to drive oif the initial coating and leave the mesh bright. Whatever the explanation may be, in fact the said step does not leave a bright mesh.
  • a metal of low light reflecting quality preferably antimony
  • the intermediate coating is preferably chromium.
  • the invention has been found to give another important advantage and experiment has shown, that the invention results in photo-cathodes of greater uniformity than cathodes produced by methods as at present practised.
  • the inclusion of a metal oxide in the coating on the mesh results also in increased sensitivity and lower dark current.
  • it is preferred to produce the coating by evaporating or sputtering on the coating material preferably antimonyin an atmosphere of oxygen. This produces a film of oxide on the mesh, with resultant improved sensitivity and lower dark currents.
  • Figure 1 shows schematically, and only so far as is necessary to an understanding of the invention, one way of carrying the said invention into effect;
  • Figure 2 is a fragmentary cross section of a signal plate, drawn on an enlarged scale;
  • Figure 3 is a fragmentary cross section of a field terminating mesh, also drawn on an enlarged scale.
  • 1 is part of the glass envelope of a Vidicon television camera tube.
  • This envelope has a fused in glass branch pipe 2.
  • the end of the envelope is 7 closed by the usual flat end glass plate 3 on the inside of which the photo-cathode, generally designated 5, is to be deposited on top of a signal plate deposit 11 constituted by tin oxide.
  • a contact ring 4 of Kovar or other suitable metal Inside the envelope is the usual metal tubular focusing electrode system 6, the otherwise open end of which is closed by a field terminating mesh 7.
  • the tubular metal electrode 6 has a side opening 8 opposite the branch pipe 2.
  • the mesh 7 is coated at 12, as by evaporating antimony thereon, before being put in place.
  • a crucible 9 containing a measured quantity of antimony trisulphide This may be, as is at present customary, antimony trisulphide with from 2 to 6% excess antimony, but, by suitably choosing the amount of antimony initially deposited on the mesh stoichiometrically pure antimony trisulphide may be, and preferably is, used.
  • the crucible is heated in the presence of an argon filling by electrical heating applied through leads in the crucible support 10 so as to evaporate its contents and produce a porous deposited layer through the mesh on the signal plate 11 on the inside of the glass end plate 3. It also produces a deposited layer on the mesh itself.
  • the crucible is then withdrawn, the envelope is pumped out to a hard vacuum, and the branch pipe 2 is sealed off to leave a mere side pipe on the envelope.
  • a high frequency eddy current heating coil (not shown) is now placed round the tube to encircle the mesh and heat is applied to raise the mesh above the evaporation temperature of antimony. This evaporates off the antimony trisulphide p'roviously deposited on the mesh and provides a second, compact, photo-cathode layer 5" on the plate 3.
  • this evaporation step is conducted at such temperature that one would expect the antimony also to be evaporated from the mesh, the fact is that the mesh remains practically dark after the said strip.
  • a method of manufacturing a camera tube having a picture receiving photo-cathode with field terminating mesh adjacent thereto including the steps of initially coating the mesh with a metal of low light reflecting quality, evaporating antimony trisulphide through said mesh in the presence of an inert gas to form a porous cathode layer, and then evaporating antimony trisulphide from said mesh to form a second compacted cathode layer.
  • the method of manufacturing a camera tube having a picture-receiving photo-cathode with a field terminating mesh adjacent thereto which includes fusing a branch tube in one side of the camera tube envelope, introducing a tubular electrode having a side opening therein into the enve.ope with the side opening of the electrode registering with the branch tube coating the mesh with a layer of metal of low light reflecting quality, introducing a measured quantity of antimony trisulphide through the branch tube and the registered side opening in said electrode, heating the antmony trisulphide in the presence of an argon filling within the envelope to produce a porous deposited layer on the terminating mesh, pumping out the envelope to a hard vacuum, sealing off the branch tube form the envelope, subjecting the mesh to a temperature above evaporation temperature of antimony for evaporating oil the antimony trisulphide previously deposited on the mesh and building up a photo-cathode layer on the picture-receiving photo-cathode.
  • a camera tube including a picture receiving photocathode with a field terminating mesh adjacent thereto wherein said mesh has an initial coating of metal of low light reflecting quality.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Physical Vapour Deposition (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US769252A 1958-01-06 1958-10-23 Television and like camera tubes Expired - Lifetime US2967962A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB442/58A GB845734A (en) 1958-01-06 1958-01-06 Improvements in or relating to television and like camera tubes

Publications (1)

Publication Number Publication Date
US2967962A true US2967962A (en) 1961-01-10

Family

ID=9704410

Family Applications (1)

Application Number Title Priority Date Filing Date
US769252A Expired - Lifetime US2967962A (en) 1958-01-06 1958-10-23 Television and like camera tubes

Country Status (5)

Country Link
US (1) US2967962A (enrdf_load_stackoverflow)
DE (1) DE1102804B (enrdf_load_stackoverflow)
FR (1) FR1213984A (enrdf_load_stackoverflow)
GB (1) GB845734A (enrdf_load_stackoverflow)
NL (2) NL233895A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3106488A (en) * 1955-02-15 1963-10-08 Emi Ltd Improved method of forming a photoconductive layer on a translucent surface
US3322570A (en) * 1962-05-25 1967-05-30 Hitachi Ltd Photosensitive electrodes and method of making same
US4217479A (en) * 1977-04-29 1980-08-12 Swiss Aluminium Ltd. High temperature reactor
US4470822A (en) * 1983-02-25 1984-09-11 Rca Corporation Method of fabricating a metalized electrode assembly
US4671778A (en) * 1986-03-19 1987-06-09 Rca Corporation Imaging device having an improved photoemissive cathode appendage processing assembly
DE3917139A1 (de) * 1988-05-27 1989-11-30 Hitachi Ltd Verfahren zur herstellung einer bildaufnahmeroehre und eines darin verwendeten speicherplattensegments
US4898557A (en) * 1986-01-21 1990-02-06 Leybold Aktiengesellschaft Process for preparing extraction grids

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1555197A (enrdf_load_stackoverflow) * 1967-03-07 1969-01-24

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB682318A (en) * 1949-01-01 1952-11-05 Emi Ltd Improvements relating to electron discharge devices such as television transmission tubes
FR1141316A (fr) * 1955-02-15 1957-08-30 Emi Ltd Tubes électroniques perfectionnés utilisant des cibles photoconductrices

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB749058A (en) * 1952-12-24 1956-05-16 Cathodeon Ltd Improvements in or relating to television pick-up tubes
NL99071C (enrdf_load_stackoverflow) * 1955-07-23
DE1028163B (de) 1956-11-27 1958-04-17 Fernseh Gmbh Anordnung zur Verbesserung des mit einer Vidikonroehre zu erzielenden Bildkontrastes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB682318A (en) * 1949-01-01 1952-11-05 Emi Ltd Improvements relating to electron discharge devices such as television transmission tubes
FR1141316A (fr) * 1955-02-15 1957-08-30 Emi Ltd Tubes électroniques perfectionnés utilisant des cibles photoconductrices

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3106488A (en) * 1955-02-15 1963-10-08 Emi Ltd Improved method of forming a photoconductive layer on a translucent surface
US3322570A (en) * 1962-05-25 1967-05-30 Hitachi Ltd Photosensitive electrodes and method of making same
US4217479A (en) * 1977-04-29 1980-08-12 Swiss Aluminium Ltd. High temperature reactor
US4470822A (en) * 1983-02-25 1984-09-11 Rca Corporation Method of fabricating a metalized electrode assembly
US4898557A (en) * 1986-01-21 1990-02-06 Leybold Aktiengesellschaft Process for preparing extraction grids
US4671778A (en) * 1986-03-19 1987-06-09 Rca Corporation Imaging device having an improved photoemissive cathode appendage processing assembly
DE3917139A1 (de) * 1988-05-27 1989-11-30 Hitachi Ltd Verfahren zur herstellung einer bildaufnahmeroehre und eines darin verwendeten speicherplattensegments

Also Published As

Publication number Publication date
NL112456C (enrdf_load_stackoverflow)
NL233895A (enrdf_load_stackoverflow)
GB845734A (en) 1960-08-24
DE1102804B (de) 1961-03-23
FR1213984A (fr) 1960-04-05

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