US3256455A - Camera tube target window epoxy seal - Google Patents

Camera tube target window epoxy seal Download PDF

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Publication number
US3256455A
US3256455A US45355665A US3256455A US 3256455 A US3256455 A US 3256455A US 45355665 A US45355665 A US 45355665A US 3256455 A US3256455 A US 3256455A
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US
United States
Prior art keywords
envelope
window
target
photoconductive
electrode
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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English (en)
Inventor
Ideal T Saldi
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General Electric Co
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General Electric Co
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Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US45355665 priority Critical patent/US3256455A/en
Priority to NL6605187A priority patent/NL6605187A/xx
Application granted granted Critical
Publication of US3256455A publication Critical patent/US3256455A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
    • H01J9/26—Sealing together parts of vessels
    • H01J9/263—Sealing together parts of vessels specially adapted for cathode-ray tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
    • H01J5/20—Seals between parts of vessels
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0033—Vacuum connection techniques applicable to discharge tubes and lamps
    • H01J2893/0037—Solid sealing members other than lamp bases
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31511—Of epoxy ether
    • Y10T428/31529—Next to metal

Definitions

  • the present invention relates to improvements in electron discharge devices for picture signal generator which employ a photosensitive element of the photoconductive type. More particularly, the invention relates to an improved envelope seal and method of assembling such tubes. This application is a continuation-in-part application of copending application Serial No. 152,503 filed November 15, 1961, and assigned to the same assignee as the present invention.
  • Picture signal generating or camera tubes which include an evacuated envelope provided with a transparent window on the interior surface of which is supported a transparent electrode and a photoconductive target element.
  • a charge pattern. is formed on the photoconductive element representative of the pattern of intensity of light passing through the window, and neutralization of this charge pattern by a scanning electron beam provides an electrical output signal representative of the video information or light pattern.
  • the electron beam generating, focusing and accelerating means occupy the major portion of the space within the envelope, and the envelope is usually of cylindrical shape, with the viewing window carrying the photoconductive layer forming one end wall of the cylinder, and the electrode leads being sealed through a header or stem which closes the other end of the cylinder.
  • One of the problems in manufacturing such camera tubes is the formation and effective incorporation within the tube of a photoconductive target layer which has a desirably high degree of uniformity in dimensions, in photosensitivity, and in electrical properties.
  • a principal object of the present invention is to provide a camera tube of the photoconductive target type having a photoconductive target of enhanced uniformity and sensitivity.
  • Another object is to provide an improved method of manufacturing and assembling camera tubes of the photoconductive target type.
  • Another object is to provide, in a camera tube having an evacuated envelope and wherein a photoconductive target-supporting viewing window forms a portion of said envelope, improved means for sealing said window to the remainder of the envelope.
  • FIG. 1 is a view, partially broken away in axial section, of a camera tube of the photoconductive target type constructed in accordance with the present invention
  • FIG. 2 is an enlarged fragmentary sectional view of a portion of the structure shown in FIG. 1;
  • FIG. 3 is an exploded view of certain of the parts shown in FIGS. 1 and 2.
  • a photoconductive targettype camera tube constructed in accordance with the present invention includes an envelope 2 having a cylindrical barrel, portion 4, which may be glass, closed at one end by a header or stem 6 through which extend leads 8 for supporting an electrode assembly including an electron gun 10, a getter 12, and the usual control, focusing and accelerating electrodes 14, 16.
  • Final accelerating electrode 16 is supported at its forward end by springs 18 engaging the interior wall of the envelope.
  • the forward end of the cylindrical portion of the envelope is closed by a target window 20.
  • an electrically conductive signal ring 22 Between the marginal portion of the target window and the adjacent end of the cylinder 4 is sandwiched an electrically conductive signal ring 22 through which the electrical output signal of the tube is obtained, as is well understood by those skilled in the art.
  • an electrically conductive transparent coating 24 (FIG. 2) electrically connected to the signal ring.
  • a layer of photoconductive target material 26 such as, for example, antimony trisulfide.
  • a mesh electrode 28 Closely spaced opposite the target and parallel thereto is a mesh electrode 28. A decelerating electrostatic field is established between the mesh electrode and the target during tube operation so as to provide a soft landing on the target for the scanning electron beam, as
  • the stem or header may be joined to the cylinder 4 by a conventional glass-to-glass seal and the stem is also provided with a tubulation 30 through which the envelope may be exhausted and ultimately completely closed.
  • target window 20 is permanently hermetically sealed to the signal ring 22 portion of the envelope by a butt-type seal 32 made of a sealing material which may be completely processed at temperatures below that having any deleterious effect on the target 26 or other portions of the tube.
  • a sealing material according to the invention is a mixture of finely divided metal and an epoxy resin having a vapor pressure of less than about 1O millimeters of mercury at a temperature of. 75 C.
  • the proportion of resin in such mixture may vary, with the balance being substantially finely divided metal such as silver, aluminum, et cetera, and a preferred formulation is about 20% by weight epoxy resin with a filling of about 80% by weight powdered silver. 'Preferably at least a part of the epoxy resin should be of a type somewhat flexible when cured, such as to absorb stresses established by any slight mismatch in thermal expansion of the seal components.
  • epoxy means a three-member ring containing one oxygen and two carbon atoms arranged as follows:
  • the epoxy resin is a molecule which contains, on the A more comprehensive description is found in Insulation, December 1960, pp. 87-101. Bisphenol A and novolacs epoxy resins have been employed with good results.
  • the signal ring 22 may be sealed to the cylinder 4 by the same means as window 20 is sealed to ring 22. Both the seal of ring 22 to the cylinder 4 and the window 20 to the ring 22 may be made simultaneously, or the ring 22 may be first separately sealed to the cylinder 4 by the sealing material herein described or by metal-to-glass sealing techniques if desired.
  • seals between the target window 20 and signal ring 22, or between the cylinder 4 and signal ring 22 the sealing surfaces are first carefully cleaned, then coated with the uncured sealing material, joined, and retained in sealed position long enough for the seals 32 to cure a solidified condition.
  • suitable Patented June 14, 1956 supporting fixtures or clamps may be employed to hold the parts while the sealing material is curing.
  • a seal 3-2 can be cured at room temperature or curing may be accelerated by subjecting the joined parts and sealing material to a heat treatment at a temperature of for example 60 C. The heat sensitive photoconductor is this protected from high processing temperatures.
  • the assembled tube then may be processed by standard techniques of exhaust, bakeout, getter flash, and so forth to complete the manufacture.
  • This invention also permits the stern and electron gun assembly to be presealed to the envelope. Accordingly, the flushing gases, for example nitrogen, and high temperatures associated with this sealing are no longer critical features to the photoconductive material.
  • the foregoing seals 32 and sealing technique affords a number of advantages.
  • the most critical portion of the tube, namely the photoconductive target 26 may be formed on the target window by an evaporative process which is not hampered by the space limitations which prevail when the target window is earlier sealed to the cylindrical portion 4 of the envelope.
  • the evaporative process may be formed simultaneously by a single evaporation process, with resulting obvious economies.
  • the targets may be readily inspected, tested and measured to any desired degree conveniently and cheaply prior to assembly to the remaining portion of the tube, and any which are not acceptable may be inexpensively rejected quite independently of the remaining portion of the tube.
  • Tubes having seals as above described have been found to have substantial resistance to thermal shock, completely acceptable vacuum tightness and satisfactorily low outgassing properties for desirably long life.
  • a camera tube including an evacuated envelope, an electron beam generating means disposed in said envelope, a target window arranged to form a portion of the wall of said envelope in the path of said electron beam, an electrode on the interior surface of said window,
  • conductive mixture of epoxy resin and finely divided metal interspersed therein said epoxy resin have a vapor pressure of not more than about 10- millimeters of mercury at 75 C.
  • a camera tube including an evacuated envelope, an electron beam generating means disposed in said envelope, a target window arranged to form a portion of a wall of said envelope in the path of said electron beam, a transparent electrode on the interior surface of said window, a layer of photoconductive material on the interior surface of said transparent electrode, and a thin hermetic butt-type seal between the marginal portion of said window and the remainder of said envelope and in electrical contact with said transparent electrode, said seal comprising an electrically conductive mixture of a powdered metal and an epoxy resin having a vapor pressure of not more than 10 millimeters of mercury at C.
  • a camera tube including an evacuated envelope, an electron beam generating means disposed in said envelope, a target window arranged to form a portion of the wall of said envelope in the path of said electron beam, a transparent electrode on the interior surface of said window, a layer of photoconductive material on the interior surface of said transparent electrode, and a thin butt-type seal between the marginal portion of said window and the remainder of said envelope and in electrical contact With said transparent electrode, said seal comprising an electrically conductive mixture of about 20% by weight epoxy resin and about by weight powdered silver interspersed therein, said epoxy resin having a vapor pressure of not more than about 10- millimeters of mercury at 75 C.
  • an envelope having a cylindrical end, a target window arranged for closing said end of said envelope, a transparent conductive electrode supported directly on the interior surface of said target window, a photoconductive target overlaying said transparent electrode, an annular metallic signal transmisison member extending between said end of said envelope and the marginal portion of said window and hermetically sealed to said end of envelope, and an electrically conductive hermetic seal between said annular member and said window marginal portion and forming an electrically conductive path between said transparent electrode and said annular signal transmission member, said seal comprising an electrically conductive mixture of a finely divided metal and an epoxy resin.
  • target window arranged for closing said end of said envelope, a transparent conductive electrode supported directly on the interior surface of said target window, a photoconductive target overlaying said transparent electrode, an annular metallic signal transmission member extending between said end of said envelope and the marginal portion of said window, an electrically conductive thin hermetic annular seal positioned concentrically between said annular member and said window marginal portion and forming an electrically conductive path between said transparent electrode and said annular signal transmission member, said seal comprising an electrically conductive mixture of about 80% by weight of finely divided silver and 20% by weight of an epoxy resin having a vapor pressure of not more than 10' millimeters of mercury at 75 C., and a thin hermetic annular epoxy resin seal concentrically positioned between said annular member and said envelope.
  • a method of assembling a photoconductive pickup camera tube comprising in the order recited (a) hermetically sealing an electron gun structure to one open end of an open ended envelope, (b) hermetically sealing a preformed photoconductive target window assembly to the other end of said envelope by means of an epoxy resin seal,
  • a target assembly comprising (a) an optically transparent window
  • said joining consisting essentially of a finely divided metal filled epoxy resin hermetically sealing said annular electrode to said Window and (f) said seal providing an electrical connection to said transparent electrode.
  • said seal includes a metal filler of finely divided metal taken from the class consisting of aluminum and silver, and said epoxy has a vapor pressure of less than about 10 millimeters of mercury at a temperature of 75 C.
  • a method of assembling a photoconductive pickup camera tube comprising in the order recited (a) hermetically sealing a glass electron gun stem structure to one end of a tubular glass envelope,

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US45355665 1965-04-26 1965-04-26 Camera tube target window epoxy seal Expired - Lifetime US3256455A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US45355665 US3256455A (en) 1965-04-26 1965-04-26 Camera tube target window epoxy seal
NL6605187A NL6605187A (enrdf_load_stackoverflow) 1965-04-26 1966-04-19

Applications Claiming Priority (1)

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US45355665 US3256455A (en) 1965-04-26 1965-04-26 Camera tube target window epoxy seal

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US3256455A true US3256455A (en) 1966-06-14

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NL (1) NL6605187A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3619685A (en) * 1970-02-16 1971-11-09 John J Miller Photoconductive pickup tube with unitized electrode structure having the photoconductive target electrode spaced from the tube faceplate
US3692379A (en) * 1971-05-24 1972-09-19 Sylvania Electric Prod Method of fabricating a photoconductive pickup tube
US3746917A (en) * 1971-05-13 1973-07-17 Gen Electric Camera tube with accurate field mesh mounting means
JPS50117729U (enrdf_load_stackoverflow) * 1974-03-07 1975-09-26
DE2539031A1 (de) * 1974-09-09 1976-03-25 Rca Corp Anordnung und verfahren zum befestigen eines plaettchens auf einem transparenten bauteil
US4113896A (en) * 1975-11-21 1978-09-12 Licentia Patent-Verwaltungs-G.M.B.H. Method of manufacturing an electrically conductive contact layer
US4940919A (en) * 1989-01-23 1990-07-10 Picker International, Inc. Support structure for vacuum tube components
US5478266A (en) * 1993-04-12 1995-12-26 Charged Injection Corporation Beam window devices and methods of making same

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2984759A (en) * 1957-03-25 1961-05-16 Rca Corp Photoconductive pick-up tube and method of manufacture

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2984759A (en) * 1957-03-25 1961-05-16 Rca Corp Photoconductive pick-up tube and method of manufacture

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3619685A (en) * 1970-02-16 1971-11-09 John J Miller Photoconductive pickup tube with unitized electrode structure having the photoconductive target electrode spaced from the tube faceplate
US3746917A (en) * 1971-05-13 1973-07-17 Gen Electric Camera tube with accurate field mesh mounting means
US3692379A (en) * 1971-05-24 1972-09-19 Sylvania Electric Prod Method of fabricating a photoconductive pickup tube
JPS50117729U (enrdf_load_stackoverflow) * 1974-03-07 1975-09-26
DE2539031A1 (de) * 1974-09-09 1976-03-25 Rca Corp Anordnung und verfahren zum befestigen eines plaettchens auf einem transparenten bauteil
US4103203A (en) * 1974-09-09 1978-07-25 Rca Corporation Wafer mounting structure for pickup tube
US4113896A (en) * 1975-11-21 1978-09-12 Licentia Patent-Verwaltungs-G.M.B.H. Method of manufacturing an electrically conductive contact layer
US4940919A (en) * 1989-01-23 1990-07-10 Picker International, Inc. Support structure for vacuum tube components
US5478266A (en) * 1993-04-12 1995-12-26 Charged Injection Corporation Beam window devices and methods of making same

Also Published As

Publication number Publication date
NL6605187A (enrdf_load_stackoverflow) 1966-10-27

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