US2075377A - Means and method of forming discrete areas - Google Patents

Means and method of forming discrete areas Download PDF

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Publication number
US2075377A
US2075377A US10883A US1088335A US2075377A US 2075377 A US2075377 A US 2075377A US 10883 A US10883 A US 10883A US 1088335 A US1088335 A US 1088335A US 2075377 A US2075377 A US 2075377A
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US
United States
Prior art keywords
cathode
silver
islands
layer
photoelectric
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
US10883A
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English (en)
Inventor
Russell H Varian
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.)
Farnsworth Television Inc
Original Assignee
Farnsworth Television Inc
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
Priority to NL43986D priority Critical patent/NL43986C/xx
Application filed by Farnsworth Television Inc filed Critical Farnsworth Television Inc
Priority to US10883A priority patent/US2075377A/en
Priority to GB6255/36A priority patent/GB471359A/en
Priority to DEF80861D priority patent/DE682470C/de
Priority to FR803418D priority patent/FR803418A/fr
Application granted granted Critical
Publication of US2075377A publication Critical patent/US2075377A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J40/00—Photoelectric discharge tubes not involving the ionisation of a gas
    • H01J40/02—Details
    • H01J40/04—Electrodes
    • H01J40/06—Photo-emissive cathodes
    • 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
    • H01J29/43—Charge-storage screens using photo-emissive mosaic, e.g. for orthicon, for iconoscope

Definitions

  • a means and method for forming a surface having a plurality of discrete, closely adjacent conductive islands to provide a mosaic photoelectric emitter; to provide a mosaic surface having a plurality of discrete conductive areas upon which photoelectric material may be deposited; to provide a means and method for preparing a silver surface for the deposition of photoelectric material thereon; to provide a means and method of condensing a vaporizable material as a discontinuous surface; and to provide a means and method for regulating the sensitivity of a photoemissive. substance during the activation thereof when deposited in discrete areas.
  • Figure 1 is a plan view of a preferred type ofv photoelectric cathode, showing the distribution of the treated surfaces thereof.
  • Figure 2 illustrates a step in the formation of a mosaic silver surface upon a preferred form of cathode.
  • Figure 3 is a longitudinal sectional view of a television dissector tube similar to that described in the application of Philo T. Farnsworth, Serial No. 668,066, filed April 26, i933, for an Image dissector, wherein the mosaic photoelectric cathode of my invention is mounted.
  • Figure 4 is a sectional view through a photoelectric cathode, on which a mosaic photoelectric layer has been formed on a loosely deposited, finely divided, insulating powder.
  • a mono-molecular layer of alkali metal on the mica surface between the islands may easily I cause a leak between the islands.
  • a mosaic photoelectric surface having small islands closeshadows when the surface is exposed to metal vapor travelling in relatively straight lines from I may prefer to ver onto such an indented surface, and-thereafter condense alkali metal or similar photoelectric material thereon.
  • I also prefer to oxidize the silver surface before the depositionof the photoelectricmaterial thereon, and l have found that a better emitter is eventuailyobtained if the oxidation is performed by oxygen ions reaching the surface 'by diffusion rather than with high velocities imparted thereto by excitation of the mosaic itself.
  • any photoelectric surface it has hitherto been quite customary to sensitize the alkali metal, for example, by creating a glow discharge within the envelope and to check the emission of the cathode during the sensitization process.
  • an emitter comprising a large number of discrete emitting particles, it is a complicated and dimcult process to do this checking by measuring the emssion of any or all of the islands.
  • the roughened indented surface may be formed in a number of ways, as the physical characteristics only of the surface are the important factors, the par- 2 ticular means by which such a surface is obtained being of less consequence.
  • I may deeply scratch and thereby roughen a relatively soft material, such as mica, to form the surface, or I may deposit upon a relatively smooth insulating surface a layer of finely divided insulating powder, preferably one of such fineness that it has adherent properties.
  • finely divided and powdered quartz is a satisfactory. material to employ, but other refractory materials will be equally satisfactory, the requirements for them being principally that the caesium be not able to combine with them, and that they may be deposited in such a way as to form overhangs.
  • a mica disc I is preferably provided with a mask, not shown, having a square opening therein. This mask is placed over the mica sheet and powdered quartz is deposited on the surface by being blown,
  • a supporting stem l2 carrying a silver chamber M on a chamber lead Iii sealed through the supporting stem.
  • the chamber I I is hollow and is provided with an aperture l6 directed toward the cathode. assembly. Within this chamber I prefer to place a quantity of pure silver I1.
  • the size of the' conductive islands, and to some extent their spacing may be controlled by varying the size, shape, and manner of deposition. If small powder grains are deposited in a dense, relatively smooth surfaced layer, the islands will be very small and close together. If, however, the same powder is laid down in a very rough manner with large groups of grains loosely attached to each other, the islands will be relatively large. If the powder grains. are made large and loosely deposited, theislands will be large and the distance between them will also be relatively large. It is therefore possible to make mosaic metal layers having practically any island dimensions desired.
  • the mosaics formed by the means and method described above are, in their average size, well below the size of the smallest elementary scanning area desired. I have also found that they do not tend to run together into linear groups, and it is of course obvious from the way in which the islands are created that they form no pattern, being indiscriminate in their relation one to another. While I have no direct evidence that the islands have a uniform average size, I do know, when the cathode is used in a television dissector, such as will be later described, that the detail pmduced in the image, as reconstructed in a receiver, definitely shows, by the uniform detail, that there is no tendency for the islands to run together to form linear streams or consolidated masses which are of sufficient size to cause any blurring in' the image therein.
  • the other end of the dissector tube. envelope is provided with an anode assembly 24.
  • This particular tube has been fully described in the above identified application, and as the particular form of dissector tube in which the cathode is used is no part of the instant invention, it will not be necessary to go into the function of this anode assembly in this application. Further processing of the cathode is carried out in the tube shown in Figure 3.
  • is connected to a pump through a stop-cock 25, and the exhaust tube 28 is provided with a connection to a source of alkali metal vapor, preferably a bulb 21, containing 45 caesium 29, and adapted to be heated by a gas flame or other source 30.
  • the tube is preferably may alsobe oxidized directly by heat or by high frequency applied to the cathode plate behind the mica, but I have found that in every case the electrodeless ring discharge gives the best surface. Why this should be I am not atthis time prepared to state, but it would appear that 65 the oxidization by means of an oxygen ion having little or no impact velocity, gives a better surface than when heat is .used or when the ions are directed into the surface with substantial impact velocity imparted by electrode poten , The bulb :1 is then heated to introduce caesium vapor into the envelope, where it comblues with the silver oxide to form a photoelectric surface on both the discrete areas and on the continuous silver area.
  • caesium vapor it is not necessary that the caesium vapor be directed onto the surface from a point source, as it appears that the caesium vapor deposits on and combineswith the silver oxide without the need for direction, but does not deposit between the islands nor on the walls to any great extent.
  • the degree of sensitivity of the device may be constantly checked by illuminating the cathode, utilizing the direct connection In to the continuous area of the cathode for a measurement of the emission therefrom, the anode assembly being used as a collector.
  • the exhaust tube 26 is sealed and the completedenvelope removed from the exhaust system. The tube is then in the condition to be utilized as a television dissector tube, as described in the above identified application.
  • a homogeneous insulating layer a layer of finely ground insulating powder, a layer of silver de-' posited in discrete areas on said powder layer. and photoelectric material deposited on said discrete areas.
  • a photoelectric mosaic cathode comprising the following layers in order: a conducting layer, a homogeneous insulating layer, a layer of adherent particles of insulating powder of heterogeneous sizes, a layer of photosensitive material deposited in discrete areas on said powder layer, said conductive layer being of at least as great an area as the, area covered by the photoelectric material, and underlying said material.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Gas-Filled Discharge Tubes (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US10883A 1935-03-13 1935-03-13 Means and method of forming discrete areas Expired - Lifetime US2075377A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL43986D NL43986C (fr) 1935-03-13
US10883A US2075377A (en) 1935-03-13 1935-03-13 Means and method of forming discrete areas
GB6255/36A GB471359A (en) 1935-03-13 1936-03-02 Improvements in means for and methods of forming mosaic electrodes for use in electric discharge tubes
DEF80861D DE682470C (de) 1935-03-13 1936-03-12 Verfahren zur Herstellung gegeneinander isolierter Flaechenstuecke eines leitenden Stoffes durch Aufdampfen auf eine isolierende Flaeche bei Mosaikelektroden
FR803418D FR803418A (fr) 1935-03-13 1936-03-13 Procédé pour faire des cathodes à mosaïque

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US10883A US2075377A (en) 1935-03-13 1935-03-13 Means and method of forming discrete areas

Publications (1)

Publication Number Publication Date
US2075377A true US2075377A (en) 1937-03-30

Family

ID=21747869

Family Applications (1)

Application Number Title Priority Date Filing Date
US10883A Expired - Lifetime US2075377A (en) 1935-03-13 1935-03-13 Means and method of forming discrete areas

Country Status (5)

Country Link
US (1) US2075377A (fr)
DE (1) DE682470C (fr)
FR (1) FR803418A (fr)
GB (1) GB471359A (fr)
NL (1) NL43986C (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2428043A (en) * 1942-10-02 1947-09-30 Int Standard Electric Corp Method of manufacturing metal electric rectifiers
US2476590A (en) * 1943-07-03 1949-07-19 Westinghouse Electric Corp Cathode coating
US2548514A (en) * 1945-08-23 1951-04-10 Bramley Jenny Process of producing secondaryelectron-emitting surfaces
US2620287A (en) * 1949-07-01 1952-12-02 Bramley Jenny Secondary-electron-emitting surface
US2671857A (en) * 1944-02-11 1954-03-09 John M Cage Micro-microwave generator
US2716203A (en) * 1947-06-23 1955-08-23 William J Sen Electronic image storage tube and system
US2860221A (en) * 1955-11-25 1958-11-11 Gen Mills Inc Method of producing a humidity sensor by shadow casting and resultant product
US2906648A (en) * 1955-11-25 1959-09-29 Gen Mills Inc Masking method of producing a humidity sensor
US2908595A (en) * 1955-11-25 1959-10-13 Gen Mills Inc Coating and grinding method of making a humidity sensor
US2926325A (en) * 1954-11-04 1960-02-23 Servomechanisms Inc Film resistor element

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE849570C (de) * 1949-04-22 1952-09-15 Fernseh Gmbh Verfahren zur Herstellung sehr feinmaschiger Netzfolien

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2428043A (en) * 1942-10-02 1947-09-30 Int Standard Electric Corp Method of manufacturing metal electric rectifiers
US2476590A (en) * 1943-07-03 1949-07-19 Westinghouse Electric Corp Cathode coating
US2671857A (en) * 1944-02-11 1954-03-09 John M Cage Micro-microwave generator
US2548514A (en) * 1945-08-23 1951-04-10 Bramley Jenny Process of producing secondaryelectron-emitting surfaces
US2716203A (en) * 1947-06-23 1955-08-23 William J Sen Electronic image storage tube and system
US2620287A (en) * 1949-07-01 1952-12-02 Bramley Jenny Secondary-electron-emitting surface
US2926325A (en) * 1954-11-04 1960-02-23 Servomechanisms Inc Film resistor element
US2860221A (en) * 1955-11-25 1958-11-11 Gen Mills Inc Method of producing a humidity sensor by shadow casting and resultant product
US2906648A (en) * 1955-11-25 1959-09-29 Gen Mills Inc Masking method of producing a humidity sensor
US2908595A (en) * 1955-11-25 1959-10-13 Gen Mills Inc Coating and grinding method of making a humidity sensor

Also Published As

Publication number Publication date
NL43986C (fr)
GB471359A (en) 1937-09-02
DE682470C (de) 1940-02-27
FR803418A (fr) 1936-09-30

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