US2901649A - Image storage screens and method of making same - Google Patents

Image storage screens and method of making same Download PDF

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Publication number
US2901649A
US2901649A US361655A US36165553A US2901649A US 2901649 A US2901649 A US 2901649A US 361655 A US361655 A US 361655A US 36165553 A US36165553 A US 36165553A US 2901649 A US2901649 A US 2901649A
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US
United States
Prior art keywords
screen
silicon monoxide
assembly
metallic
insulator
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
US361655A
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English (en)
Inventor
Albert J Knight
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.)
TDK Micronas GmbH
International Telephone and Telegraph Corp
Original Assignee
Deutsche ITT Industries GmbH
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 NL100627D priority Critical patent/NL100627C/xx
Application filed by Deutsche ITT Industries GmbH filed Critical Deutsche ITT Industries GmbH
Priority to US361655A priority patent/US2901649A/en
Priority to GB17291/54A priority patent/GB767139A/en
Priority to FR1107561D priority patent/FR1107561A/fr
Priority to US569723A priority patent/US2931914A/en
Priority to FR71651D priority patent/FR71651E/fr
Application granted granted Critical
Publication of US2901649A publication Critical patent/US2901649A/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
    • 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
    • H01J29/023—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof secondary-electron emitting electrode arrangements
    • 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
    • H01J29/395—Charge-storage screens charge-storage grids exhibiting triode effect
    • 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
    • H01J31/506—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output tubes using secondary emission effect
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H01J43/24—Dynodes having potential gradient along their surfaces
    • 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

Definitions

  • the present invention relates to image storage screens, and particularly to unitary insulator screens for use in television image tubes and to the method of making such screens.
  • Television tubes employing the screen of this invention may be of either the camera pick-up type or of the picture-reproducing type.
  • One specific form of television tube with which the present invention may be used is illustrated and described in the March 1953 edition of Electronics magazine on page 126.
  • picture or image information is written on a planar storage screen composed of insulating material.
  • an electrical charge pattern is left on the surface of the insulator screen which for practical purposes may be considered as an electrical duplicate of the picture information written thereon.
  • this charge pattern will remain on the screen for a considerable period of time, and by employing different known reading techniques, this information may be utilized to produce either a luminescent image or an electrical signal for utilization in the transmission of the picture information from one point to another.
  • One form comprises a metallic mesh backing which is coated with a suitable insulating material, such coating being limited to the metallic screen elements only thereby leaving the mesh openings unobstructed.
  • Another form of storage screen consists of an insulator only, such insulator being composed of silica as disclosed in Law Patent 2,572,497 issued October 23, 1951.
  • each of these two forms of screens possesses an advantage over the other.
  • the high capacity between the insulator coating and the metallic backing of the first-mentioned screen is undesirable because of the inability to produce high differences of charge potential between the metallic screen and the coating surface. Included in this disadvantage, is the fact that considerable power is required to obtain a desired difierence of potential on the screen thereby interfering with the tube operating characteristic of sensitivity.
  • the storage screen composed intirely of an insulating material such as silica, overcomes the disadvantage just explained by providing a fine mesh screen of low capacity, which may easily be imprinted with a charge pattern characterized by high differences of charge potential.
  • the Law patent mentioned supra discloses such an insulator screen, but possesses the disadvantage of being extremely difiicult to produce and extremely frangible in quality.
  • such an improved screen is provided by following the steps of evaporating a coating of silicon monoxide on one side of a flat metallic screen of desired mesh size, etching the metal away from the silicon monoxide coating, and heat treating the remaining silicon monoxide screen to relieve stresses and strains for increasing screen strength.
  • Figure 1 is a cross section of a structure exemplifying one step in the method of this invention
  • Figure 2 is a similar sectional view exemplifying another step in the method of this invention.
  • FIG. 3 is a cross section of an assembly used in following the teaching of this invention.
  • Figure 4 is a fragmental section of an insulator screen achieved by means of the present invention.
  • Figure 5 is a diagrammatic illustration of the present invention incorporated in a television tube.
  • a nickel or copper screen having a suitable mesh size is applied to the upper surface of a metal ring 1.
  • This screen may be of either copper or nickel composition, but in the preferred embodiment, nickel is used.
  • Another metal ring 2 is superposed on the outer peripheral margin of the nickel screen 3 and welded thereto and also to the supporting ring 1 for securing the assembly together.
  • the screen 3 is wrinkled, and since the final product must be substantially flat, it is necessary to remove the wrinkled condition by suitable heat treating.
  • This supporting structure comprises a stepped supporting ring 4 which receives the ring 1 of the screen assembly, and suitable legs 5 for supporting the ring 4.
  • a boat or metallic vessel composed of tantalum, indicated by the reference numeral 6, is placed on the floor of an evacuated container, such as a bell jar, in which the assembly at Figure 2 is placed.
  • a charge of material, such as silicon monoxide crystals, which when heated will liberate silicon monoxide, is placed in the boat 6 in position to be exposed to the underside of the screen 3.
  • An electrical current is passed through the boat 6 serving to heat the charge causing the liberation or evaporation of silicon monoxide, which flows upwardly toward the screen 3. This evaporating process is continued until a coating of silicon monoxide of three-tenths to four-tenths mil in thickness is deposited on the underside of the screen 3.
  • the screen assembly comprising a silicon monoxide coated nickel screen is removed from the bell jar and placed on a flat, fired lava disc 8 which is provided with a flat upper surface 9 and a stepped outer periphery as seen in Figure 3.
  • This annular step indicated by the reference numeral 7, receives the ring 1 of the screen assembly to position the silicon monoxide face 3a of the 10 of filter paper approximately equal to the inner perimentral size of the ring 1, is placed against the nickel screen backing and is wetted with distilled water.
  • This filter paper should be ofthelowest ash content possible and possess the highest degree of porosity.
  • the mounting ringl is now cut away from the metal-insulator screen by the use of a surgeons scapel, or the like, leaving only the screen itself, backed by the wet filter paper, on the disc surface 9.
  • a heavy coarse stainless steel screen 11 is superposed onto the filter paper 10 thereby clamping the assembly together. It should be noted at this point in the process, that every care is exercised in order to avoid handling of the insulator coated screen 3, which would tend to bend or buckle it.
  • the assembly as illustrated in Figure 3, is now immersed in a solution of either hydrochloric or nitric acid, this solution being of low concentration in order to obtain slow dissolution or etching away of the metallic screen.
  • a solution of ten percent nitric acid at room temperature has been found to perform satisfactorily. It has been found that the silicon monoxide coating on the screen is so frangible that active bubbling reaction between an acid and metallic screen backing will distort and sometimes fracture the silicon monoxide.
  • the assembly is carefully rinsed with tap water.
  • the stainless steel mesh 11 is removed and the assembly is again carefully rinsed with distilled water.
  • a quartz 'or fired lava disc having a flat surface is placed against the filter paper.
  • the resulting assembly resembles a sandwich with an unbacked insulator screen and filter paper between the smooth surfaces of the lava discs.
  • the assembly is now dried at a temperature of approximately 50 centigrade for approximately one hour. Then the temperature is gradually raised in a suitable oven containing an oxidizing atmosphere, to a temperature of approximately 700 centigrade. Temperatures in the range of 300 centigrade to 1l00 centigrade have been used, but best results have been obtained by the use of temperatures ranging from 600 Centigrade to 800 centigrade. This optimum temperature is held for about eighteen hours, the assembly then being allowed to cool slowly with the oven to approximately 100 Centigrade. At this time, the compact, screen assembly, is removed from the oven. The filter paper will have burned out of the assembly leaving negligible ash. The insulator screen itself will tend to curl slightly, but by reason of the heat treatment, it may be gently handled with tweezers. without breaking.
  • the final step involves the mounting of the insulator screen on a quartz supporting ring by the use of suitable cement, such as a 2% solution of potassium silicate.
  • suitable cement such as a 2% solution of potassium silicate.
  • the mounted screen is then heat treated in air at a temperature of 500 centigrade for approximately thirty minutes to bake thoroughly the potassium silicate.
  • the resulting product consisting of only a mounting ring and a solid insulator screen is now ready for use in a television tube structure.
  • Such a tube is diagrammatically illustrated in Figure and the screen is indicated by the reference numeral 12.
  • the screen is indicated by the reference numeral 12.
  • a number of other conventional electrodes comprising a beam-forming cathode 14, a beam modulating grid 15, an accelerating electrode 16, an electron-flood cathode 17, suitable magnetic beam-deflecting coils 18, an accelerator electrode 19 which consists of a conductive coating on the inner wall of the envelope 13, a fine mesh metallic collector screen 20 which is mounted adjacent the cathode side of the storage screen 12, and a luminescent screen 21 provided on the end face plate 22 of envelope 13. All of these electrodes are provided with operating potentials as illustrated and in a manner well known to the art.
  • the beam of electrons, indicated by reference numeral 23, emitted by the cathode 14 is modulated and deflected in accordance with picture information conducted to the grid 15 and to the deflecting coils 18, for scanning the cathode side of the screen 12.
  • the potentials applied to the various electrodes are such as to impart a velocity to the electrons in the beam 23, which will produce greater than unity secondary emission from the impinged areas of the storage screen 12.
  • the electrons of the beam 23 modulated in accordance with the signal impressed upon the grid electrode 15, upon striking this elemental area causes the emission of secondary electrons.
  • a positive charge will be developed on this area depending upon the number of secondarily emitted electrons.
  • a charge pattern of positive polarity will be developed on the screen 12 in which the individual elemental area charges will have potential values respectively depending upon the velocity or beam density of the beam 23.
  • the cathode 17 Upon completing a scansion of the screen 12, the cathode 17 is caused to emit a flood of low velocity electrons, which covers the entire storage screen area, the electrons passing through the mesh openings to impinge upon the luminescent screen 21. Since the charge areas around the individual mesh openings in the screen 12 vary in accordance with the electrical image stored thereon, the flood electrons passing through any given mesh opening will be modulated in accordance with such charge and will transfer this modulation to the luminescent screen 21. By this means, a visible image is produced by the screen 21 in a manner well known to the art.
  • an insulator screen of this invention is primarily due to the low capacity thereof. This property enables the electron beams 23 to produce relatively high differences of charge potential on the elemental areas of the screen 12.
  • a low capacity electrode of this type greatly increases the sensitivity and picture contrast, and, therefore, provides a picture of greater fidelity.
  • the storage screen produced by following the teachings of this invention is composed of solid strands rather than hollo w ones as obtained in following the process of Law Patent 2,572,497-.
  • the screen of the present invention is also stronger and less frangible.
  • the method of forming a fine mesh image storage screen comprising the steps'of evaporating in a vacuum a coating of silicon monoxide on one side only of a metallic screen, etching said metallic screen away leaving only said coating of silicon monoxide in the form of said metallic screen, and heat treating the silicon monoxide screen at a predetermined temperature and for a predetermined period of time to reduce its frangibleness.
  • the method of forming a fine mesh image storage screen comprising the steps of evaporating in a vacuum a coating of silicon monoxide on one side only of a metallic screen, placing the coated screen in an acid bath to remove the metallic screen and to form a unitary silicon monoxide screen, and heat treating the silicon monoxide screen at a predetermined temperature and for a predetermined period of time to reduce its frangibleness.
  • the method of forming a fine mesh metallic screen comprising the steps of flattening a metallic screen, evaporating in a vacuum a coating of silicon monoxide on one side only of said screen, simultaneously etching the metallic screen away and maintaining the resulting unitary silicon monoxide screen in flattened condition, and heat treating the silicon monoxide screen under such conditions as to at least partially covert it to silicon dioxide while maintaining it in flattened condition.
  • a fine mesh storage screen having strands composed predominantly of silicon monoxide and having a mesh size of between about 500 mesh and 1000 mesh, the physical characteristics of such screen being such as to permit its handling for atfixation to a supporting structure, said strands being solid and without cracks.
  • the method of forming a fine mesh image storage screen comprising the steps of evaporating in a vacuum a coating of silicon monoxide on one side only of a metallic screen, dissolving the metallic screen in an acid bath of low concentration which will not cause bubbling to an extent which will fracture the coating of silicon monoxide, and heat treating the silicon monoxide screen at a temperature and for a period of time which will reduce the frangibleness thereof.
  • the method of forming a fine mesh image storage screen comprising the steps of: applying a fine mesh metal screen to a metal ring; securing said metal screen to said ring; heating said screen and ring assembly at an elevated temperature for a predetermined time and subsequently cooling the same thereby to tighten and straighten said metal screen; supporting said metal screen and ring assembly above a receptacle in a container; placing a quantity of silicon monoxide in said receptacle; evacuating said container; heating said silicon monoxide in said receptacle to evaporate said silicon monoxide onto the surface of said metal screen facing said receptacle, thereby to coat said surface with silicon monoxide; removing said metal screen and ring assembly from said container and placing the same onto a flat disc of material having low heat conductivity with said silicon monoxide coating abutting said disc; placing a piece of relatively thin paper on top of said metal screen; cutting said ring away from said metal screen; placing a relatively heavy coarse metal screen on top of said paper; immersing

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Luminescent Compositions (AREA)
US361655A 1953-06-15 1953-06-15 Image storage screens and method of making same Expired - Lifetime US2901649A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NL100627D NL100627C (fr) 1953-06-15
US361655A US2901649A (en) 1953-06-15 1953-06-15 Image storage screens and method of making same
GB17291/54A GB767139A (en) 1953-06-15 1954-06-11 Image storage screens and method of making same
FR1107561D FR1107561A (fr) 1953-06-15 1954-06-15 écrans emmagasineurs d'images et procédé de fabrication
US569723A US2931914A (en) 1953-06-15 1956-03-06 Electron multiplier mosaics
FR71651D FR71651E (fr) 1953-06-15 1957-03-05 écrans emmagasineurs d'images et procédé de fabrication

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US361655A US2901649A (en) 1953-06-15 1953-06-15 Image storage screens and method of making same

Publications (1)

Publication Number Publication Date
US2901649A true US2901649A (en) 1959-08-25

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US361655A Expired - Lifetime US2901649A (en) 1953-06-15 1953-06-15 Image storage screens and method of making same

Country Status (4)

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US (1) US2901649A (fr)
FR (2) FR1107561A (fr)
GB (1) GB767139A (fr)
NL (1) NL100627C (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3015586A (en) * 1958-01-15 1962-01-02 Itt Method of making charge storage electrodes for charge storage tubes
US3181021A (en) * 1957-06-20 1965-04-27 Itt Target electrode for barrier grid storage tube
US3295006A (en) * 1964-02-03 1966-12-27 Rca Corp Unannealed nickel screen grid mesh for pickup tubes
US3928160A (en) * 1973-10-05 1975-12-23 Hitachi Ltd Colour pickup tubes and method of manufacturing the same
US4083708A (en) * 1976-09-15 1978-04-11 Exxon Research & Engineering Co. Forming a glass on a substrate

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1786154A (en) * 1929-06-27 1930-12-23 Wilbur B Driver Radiotube
US2261154A (en) * 1939-07-22 1941-11-04 Univ Leland Stanford Junior Grid structure for high frequency apparatus
US2491761A (en) * 1946-05-11 1949-12-20 H I Thompson Company Method of producing silica fibers and fibrous articles produced thereby
US2506604A (en) * 1947-02-01 1950-05-09 Robert P Lokker Method of making electronic coils
US2572497A (en) * 1948-11-30 1951-10-23 Rca Corp Making fine mesh silica screens
US2596617A (en) * 1948-12-29 1952-05-13 Bell Telephone Labor Inc Increasing number of holes in apertured metal screens
US2739907A (en) * 1950-07-20 1956-03-27 Nowak Rudolf Process for imparting an improved finish to the surface of metals by means of diffusion treatment

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1786154A (en) * 1929-06-27 1930-12-23 Wilbur B Driver Radiotube
US2261154A (en) * 1939-07-22 1941-11-04 Univ Leland Stanford Junior Grid structure for high frequency apparatus
US2491761A (en) * 1946-05-11 1949-12-20 H I Thompson Company Method of producing silica fibers and fibrous articles produced thereby
US2506604A (en) * 1947-02-01 1950-05-09 Robert P Lokker Method of making electronic coils
US2572497A (en) * 1948-11-30 1951-10-23 Rca Corp Making fine mesh silica screens
US2596617A (en) * 1948-12-29 1952-05-13 Bell Telephone Labor Inc Increasing number of holes in apertured metal screens
US2739907A (en) * 1950-07-20 1956-03-27 Nowak Rudolf Process for imparting an improved finish to the surface of metals by means of diffusion treatment

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3181021A (en) * 1957-06-20 1965-04-27 Itt Target electrode for barrier grid storage tube
US3015586A (en) * 1958-01-15 1962-01-02 Itt Method of making charge storage electrodes for charge storage tubes
US3295006A (en) * 1964-02-03 1966-12-27 Rca Corp Unannealed nickel screen grid mesh for pickup tubes
US3928160A (en) * 1973-10-05 1975-12-23 Hitachi Ltd Colour pickup tubes and method of manufacturing the same
US4083708A (en) * 1976-09-15 1978-04-11 Exxon Research & Engineering Co. Forming a glass on a substrate

Also Published As

Publication number Publication date
FR1107561A (fr) 1956-01-03
NL100627C (fr)
GB767139A (en) 1957-01-30
FR71651E (fr) 1960-01-13

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