US3758802A - Improved cathode ray tube having a glass envelope coated with crystallized glass - Google Patents

Improved cathode ray tube having a glass envelope coated with crystallized glass Download PDF

Info

Publication number
US3758802A
US3758802A US00107900A US3758802DA US3758802A US 3758802 A US3758802 A US 3758802A US 00107900 A US00107900 A US 00107900A US 3758802D A US3758802D A US 3758802DA US 3758802 A US3758802 A US 3758802A
Authority
US
United States
Prior art keywords
cathode ray
glass
ray tube
electrodes
coating
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
US00107900A
Other languages
English (en)
Inventor
T Kubo
M Itazu
H Yamashita
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.)
NEC Corp
Original Assignee
Nippon Electric 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 Nippon Electric Co Ltd filed Critical Nippon Electric Co Ltd
Application granted granted Critical
Publication of US3758802A publication Critical patent/US3758802A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • H01J29/86—Vessels; Containers; Vacuum locks
    • H01J29/88—Vessels; Containers; Vacuum locks provided with coatings on the walls thereof; Selection of materials for the coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/88—Coatings
    • H01J2229/882—Coatings having particular electrical resistive or conductive properties

Definitions

  • a cathode ray tube including an electron gun enclosed by a glass envelope including a neck portion is disclosed in accordance with the teachings of the present invention wherein arcing between electrodes of the cathode ray tube is minimized by providing a coating of crystallized glass formed by heat-treatment of sealing glass, on the surface of the inner wall of said neck portion and coextensive with said electron gun, and a coating of conductive material, spaced from said coating of crystallized glass, on the surface of the inner wall of said neck portion.
  • a method of treating a cathode ray tube to minimize arcing between the electrodes thereof is also disclosed.
  • the cathode ray tube adapted for'television and especially color television reception requires high voltage for the effective operation'thereof, which voltage attains a value up to 27,000 volts.
  • Such cathode ray tubes usually consist of a glass envelope having a neck portion and a viewing screen disposed at opposite ends of said envelope.
  • This electron gun structure includes a cathode which serves as the source for the beam of electrons and a plurality of electrodes.
  • One or several of these electrodes may comprise accelerating anodes and others of said electrodes may comprise control grids which cooperate with the accelerating anodes to focus the beam of electrons onto the viewing screen with the proper intensity.
  • the surface of the inner wall of the neck portion of the glass envelope may be coated with conductive material such as graphite which acts as an additional anode to provide a final focus to the beam of electrons.v
  • arcing a vacuum discharge phenomenon commonly known as arcing, which may damage the display screen, the glass envelope and portions of the electron gun.
  • Arcing may be attributed to roughness of, projections from, and irregularities in the electrodes of the cathode ray tube.
  • high voltage treatment or spot knocking whereina voltage greater than the normal operating voltage of the cathode ray tube is applied to the electrodes thereof.
  • the applied voltage is usually equal to twice the normal operating voltage or about 60,000 volts.
  • An attendant disadvantage of the high voltage treatment as heretofore utilized by the prior art is the production of a potential gradient along the surface of the inner wall of the neck portion of the glass envelope due to the application of the high voltage between the cathode and the graphite coating on the glass envelope. Since the graphite coating is supplied with the high anode voltage, a portion of the surface of the inner wall of the neck portion of the glass envelope is maintained at a relatively high voltage potential. Consequently the glass wall undergoes a concentrated electron bombardment from an electrode supplied with a relatively low voltage potential. The concentrated electron bombardment produces a heating of the glass wall resulting in punctured and cracked portions of the glass envelope.
  • the magnitude of the voltages applied to the electrodes of the cathode ray tube during thehigh voltage treatment and the time duration of such high voltage treatment must be strictly limited to avoid damage of the glass envelope.
  • such limitations may forestall the successful completion of the high voltage treatment such that the aforementioned irregularities which contribute to arcing are not removed.
  • a further object of the present invention is to provide a cathode ray tube which is adapted to receive a higher operating voltage then heretofore utilized by the prior art.
  • Yet another object of this invention is to provide a method of treating a cathode ray tube whereby arcing between the electrodes thereof is minimized during normal operation.
  • an improved cathode ray tube including an electron gun enclosed by a glass envelope
  • a film of crystallized glass formed by heat-treatment of sealing glass is coated on the surface of the inner wall of said glass envelope, the coating being coextensive with said electron gun.
  • a cathode ray tube treated in accordance with the method of the present invention exhibits minimal arcing between the electrodes thereof during normal operation.
  • a cathode ray tube which may be utilized in a color television receiver and includes a unipoten'tial electron gun I comprised-of a cathode assembly 2, a
  • the electron gun assembly 1 is sealingly enclosed in the neck portion 8 of an evacuated glass envelope. It is understood that a display screen, although not shown, is provided at one end of the glass envelope oppositely disposed from stem portion 11 of the neck 8.
  • the cathode assembly 2 serves as the source for the beam of electrons and may comprise a conventional cathode such as an indirectly heated oxide coated cathode.
  • the various electrodes 4 through 7 may comprise control grids, accelerating anodes and focusing electrodes, well known in the prior art, the-description of which need not be set forth in detail herein for a complete understanding of the present'invention.
  • conductive material 9 such as a graphite layer, which coating may extend from the mid-portion of neck 8 into the bulb portion of the glass envelope, not shown. It is recognized by those skilled in the cathode ray tube art that conductive coating 9 may act as an accelerating anode or a focusing electrode.
  • one or more of the electrodes 3 through 7 as well as the conductive coating 9 may be provided with irregularities such as contaminations, roughness or protrusions, which may result in deleterious arcing effects during normal operation of the cathode ray tube. Accordingly, it is preferable to provide high voltage treatment of the assembled cathode ray tube to remove such irregularities from the electrodes.
  • a high voltage of about twice the magnitude of the normal operating voltage is applied to electrodes 5 and 7-and a low potential such as ground potential is applied to electrodes 3, 4 and 6.
  • the high voltages applied to the aforementioned electrodes results in arcing and electrons will be emitted from electrode 6 to bombard the electrodes 5 and 7- oppositely disposed thereto. It is clear however that the electrons emitted from electrode 6 will also bombard that portion of the surface of the inner wall of neck portion 8 that is oppositely disposed from electrode 6.
  • the concentrated bombardment of the glasswall of neck 8 may produce a heating of the glass wall causing thermal breakdown thereof resulting in electrical-puncture or breakage of theglass.
  • this portion of the glass tube wall surface is provided with the abovementioned kind of protective coating film 10 made of materials different from that of the glass tube so as to encircle the electrodes. Then, the electrons would be reflected or absorbed by this protective coating film, so that the direct effect of the electrons does not reach up to the glass wall. If the protective coating 10 admits of a rough surface then the increase in surface area is effective to decrease the concentration of electrons per unit area communicated thereto, resulting in a further improvement of the protective qualities of the coating
  • the protective coating 10 is preferably comprised of a film of material such as sealing glass manufactured by the Corning Glass Works. A complete description of the method of making sealing glass as well as the composition and attributes thereof may be found in U.S.
  • the protective coating 10 is comprised of a film of crystallized glass formed by heat-treatment of sealing glass.
  • the protective coating 10 having a rough surface, may beattained.
  • 200 grams of crystalline glass powder such as sealing glass powder, having a particle size of less than 100 mesh is suspended in a mixture of 125 c.c. of acetone and 0.5 grams of nitrocellulose.
  • the suspension is then deposited on the surface of the inner wall of neck portion 8 such as by spraying or by applying the suspension with a brush.
  • the thickness of the protective coating 10 although critical, admits Consequently the thickness of the protective coating 10 is preferably within the range of to 800 microns.
  • the suspension after being deposited on the surface of the inner wall of the neck portion 8, is subjected to natural drying and is then heated in air at a temperature of about 450C to rigidly secure the protective coating to the glass wall.
  • a cathode ray tube provided with a film of protective coating 10 as described hereinabove is particularly adapted for high voltage treatment to thereby minimize arcing between electrodes thereof during normal operation. It has been found that the high voltage potential applied to the electrode of a cathode ray tube of the present invention during high voltage-treatment thereof may exceed the voltage potentials hereinbefore applied by the prior art by approximately 10,000 to 20,000
  • the cathode ray tube is not limited to television and may include'other uses such as an oscilloscope, a'radar screen, an optical read out device or the like. Therefore, it will be obvious to those skilled in the art that the foregoing and various other changes and modifications in form and details may be made without departing from the spirit and scope of the invention. It is intended that the appended claims be interpreted as including all such changes and modifications.
  • the improvement comprisofa wide range. If the thickness of the coating 10 is too thin then proper protection is not afforded the glass wall of neck portion 8 and electron bombardment during high voltage treatment may produce sufficient heat to damage the wall. Conversely, if the thickness of the coating 10 is too thick, the coating will readily peel off.

Landscapes

  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US00107900A 1970-01-23 1971-01-20 Improved cathode ray tube having a glass envelope coated with crystallized glass Expired - Lifetime US3758802A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45006644A JPS5023591B1 (de) 1970-01-23 1970-01-23

Publications (1)

Publication Number Publication Date
US3758802A true US3758802A (en) 1973-09-11

Family

ID=11644063

Family Applications (1)

Application Number Title Priority Date Filing Date
US00107900A Expired - Lifetime US3758802A (en) 1970-01-23 1971-01-20 Improved cathode ray tube having a glass envelope coated with crystallized glass

Country Status (5)

Country Link
US (1) US3758802A (de)
JP (1) JPS5023591B1 (de)
FR (1) FR2076908A5 (de)
GB (1) GB1300503A (de)
NL (1) NL7100543A (de)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3979632A (en) * 1974-07-17 1976-09-07 Gte Sylvania Incorporated Cathode ray tube having surface charge inhibiting means therein
US4018717A (en) * 1975-09-29 1977-04-19 Owens-Illinois, Inc. Arc suppression in a cathode ray tube
US4119885A (en) * 1975-01-12 1978-10-10 U.S. Philips Corporation Cathode ray tube
US4285990A (en) * 1980-07-25 1981-08-25 Rca Corporation Method for coating a selected portion of the internal neck surface of a CRT
US4323813A (en) * 1980-01-23 1982-04-06 Rca Corporation Spring-loaded resistive lens structure for electron gun
US4353006A (en) * 1980-05-28 1982-10-05 Rca Corporation CRT with means for suppressing arcing therein
US4473774A (en) * 1982-02-09 1984-09-25 Rca Corporation CRT with internal neck coating for suppressing arcing therein
US4491764A (en) * 1982-09-27 1985-01-01 Rca Corporation Arc suppression structure for an electron gun
US4514661A (en) * 1982-09-27 1985-04-30 Rca Corporation Arc-suppression means for an electron gun having a split electrode
US4518893A (en) * 1982-11-23 1985-05-21 Rca Corporation CRT with internal neck coating of crystalline tin oxide for suppressing arcing therein
US4531075A (en) * 1982-09-27 1985-07-23 Rca Corporation Electron gun having arc suppression means
US4713879A (en) * 1985-03-28 1987-12-22 U.S. Philips Corporation Method of manufacturing a device having an electric resistance layer and the use of the method
US4827184A (en) * 1987-01-21 1989-05-02 U.S. Philips Corporation Electron beam device and a focusing lens therefor
US6380663B1 (en) * 1997-12-24 2002-04-30 Hamamatsu Photonics K.K. Gas discharge tube having a side tube with glass coating
US20180180216A1 (en) * 2015-09-16 2018-06-28 Wenhua Zhu Large micro-crystallized glass-lined pipeline and manufacturing method thereof

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2568459A (en) * 1948-10-29 1951-09-18 Gen Electric Electric discharge device
US2761990A (en) * 1954-02-19 1956-09-04 Rauland Corp Color television image reproducer
US3279941A (en) * 1963-02-14 1966-10-18 Corning Glass Works Method of forming a moisture-collecting coating of porous glass
US3313975A (en) * 1964-07-06 1967-04-11 Hughes Aircraft Co Electron impervious flexible shield member for electron discharge tubes

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2568459A (en) * 1948-10-29 1951-09-18 Gen Electric Electric discharge device
US2761990A (en) * 1954-02-19 1956-09-04 Rauland Corp Color television image reproducer
US3279941A (en) * 1963-02-14 1966-10-18 Corning Glass Works Method of forming a moisture-collecting coating of porous glass
US3313975A (en) * 1964-07-06 1967-04-11 Hughes Aircraft Co Electron impervious flexible shield member for electron discharge tubes

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3979632A (en) * 1974-07-17 1976-09-07 Gte Sylvania Incorporated Cathode ray tube having surface charge inhibiting means therein
US4119885A (en) * 1975-01-12 1978-10-10 U.S. Philips Corporation Cathode ray tube
US4018717A (en) * 1975-09-29 1977-04-19 Owens-Illinois, Inc. Arc suppression in a cathode ray tube
US4323813A (en) * 1980-01-23 1982-04-06 Rca Corporation Spring-loaded resistive lens structure for electron gun
US4353006A (en) * 1980-05-28 1982-10-05 Rca Corporation CRT with means for suppressing arcing therein
US4285990A (en) * 1980-07-25 1981-08-25 Rca Corporation Method for coating a selected portion of the internal neck surface of a CRT
US4473774A (en) * 1982-02-09 1984-09-25 Rca Corporation CRT with internal neck coating for suppressing arcing therein
US4491764A (en) * 1982-09-27 1985-01-01 Rca Corporation Arc suppression structure for an electron gun
US4514661A (en) * 1982-09-27 1985-04-30 Rca Corporation Arc-suppression means for an electron gun having a split electrode
US4531075A (en) * 1982-09-27 1985-07-23 Rca Corporation Electron gun having arc suppression means
US4518893A (en) * 1982-11-23 1985-05-21 Rca Corporation CRT with internal neck coating of crystalline tin oxide for suppressing arcing therein
US4713879A (en) * 1985-03-28 1987-12-22 U.S. Philips Corporation Method of manufacturing a device having an electric resistance layer and the use of the method
US4827184A (en) * 1987-01-21 1989-05-02 U.S. Philips Corporation Electron beam device and a focusing lens therefor
US6380663B1 (en) * 1997-12-24 2002-04-30 Hamamatsu Photonics K.K. Gas discharge tube having a side tube with glass coating
US20180180216A1 (en) * 2015-09-16 2018-06-28 Wenhua Zhu Large micro-crystallized glass-lined pipeline and manufacturing method thereof

Also Published As

Publication number Publication date
FR2076908A5 (de) 1971-10-15
JPS5023591B1 (de) 1975-08-08
GB1300503A (en) 1972-12-20
DE2102587A1 (de) 1971-10-14
DE2102587B2 (de) 1973-01-04
NL7100543A (de) 1971-07-27

Similar Documents

Publication Publication Date Title
US3758802A (en) Improved cathode ray tube having a glass envelope coated with crystallized glass
US2233786A (en) Fluorescent screen assembly and method of manufacture
US2164595A (en) Method of coating electrodes
US4297612A (en) Electron gun structure
GB1036859A (en) Improvements in and relating to charge image storage apparatus
US4288719A (en) CRT With means for suppressing arcing therein
US3159442A (en) Production of thin films
US2545120A (en) Cathode-ray tube arc-over preventive
US2123957A (en) Electron tube
US2843777A (en) Cathode-ray tubes
US3725710A (en) Method of making a cathode-ray tube
US3979632A (en) Cathode ray tube having surface charge inhibiting means therein
US2200911A (en) Sealed lead-in for cathode-ray tubes and the like
US2700626A (en) Secondary electron emissive electrodes
US3904502A (en) Method of fabricating a color display screen employing a plurality of layers of phosphors
US2874077A (en) Thermionic cathodes
JP3272764B2 (ja) 陰極線管及び陰極線管の製造方法
GB302307A (en) Improvements relating to electron discharge apparatus
US3099763A (en) Cathode ray tube with silica coated phosphor screen
US2171230A (en) Insulating coating
US2035003A (en) Electron discharge device
JPH023262B2 (de)
US3771003A (en) Shielded cathode ray tube electron gun
US2824249A (en) Storage grid for direct-viewing storage tubes
US2129015A (en) Braun tube