US3658401A - Method of manufacture of cathode ray tubes having frit-sealed envelope assemblies - Google Patents

Method of manufacture of cathode ray tubes having frit-sealed envelope assemblies Download PDF

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Publication number
US3658401A
US3658401A US959A US3658401DA US3658401A US 3658401 A US3658401 A US 3658401A US 959 A US959 A US 959A US 3658401D A US3658401D A US 3658401DA US 3658401 A US3658401 A US 3658401A
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Prior art keywords
envelope
envelopes
gas
frit
sealing
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US959A
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John Austin Files
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RCA Licensing Corp
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RCA Corp
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Assigned to RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, PRINCETON, NJ 08540, A CORP. OF DE reassignment RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, PRINCETON, NJ 08540, A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: RCA CORPORATION, A CORP. OF DE
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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
    • H01J29/94—Selection of substances for gas fillings; Means for obtaining or maintaining the desired pressure within the tube, e.g. by gettering
    • 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
    • H01J9/38—Exhausting, degassing, filling, or cleaning vessels

Definitions

  • the present invention relates to an improvement in the manufacture of a cathode ray tube having an envelope or bulb comprising a faceplate panel frit-sealed to a funnel.
  • a cathode ray tube is the well-known shadow mask type of color picture tube, wherein a color selection shadow mask is mounted in a faceplate panel adjacent to the faceplate, the color phosphor screen is produced on the faceplate by a photographic process using the mask as a stencil, and the completed panel is sealed to a separate funnel to form the envelope.
  • the seal between the panel and funnel is usually made by forming a bead of devitrifiable glass frit on the mating edge of one of the parts, by applying a suspension or slurry of a special powdered glass mixed with an organic binder and vehicle, assembling the two parts, and placing the assembly in an oven or lehr having a maximum temperature between 400 and 500 C., to devitrify and harden the frit, as disclosed in Claypoole U.'S. Pat. No. 2,889,952, dated June 9, 1959.
  • the envelope is subjected to various operations, including insertion and mounting of the electron gun and getter in the funnel, cathode activation, bake and exhaust to remove most of the gas and other impurities, tipoff, getter flash, and ageing.
  • the function of the getter is to chemically or physically sorb residual gases present or produced within the envelope during the life of the cathode ray tube.
  • the tube life is largely dependent upon the getter sorption capacity," or. the capability of the getter to sorb gases. Two factors of importance are (l) the initial getter sorption capacity, and (2) the rate of depletion of getter sorption capacity (e.g. per hour) during tube life.
  • the contaminating materials appear to be organic and/or inorganic materials, including hydrocarbons, carbon dioxide and water vapor, produced in the fritseal process itself. It appears that, when the envelope is held for a relatively long period after frit-seal and before exhaust, these materials become combined with the internal surfaces of the envelope, mask or screen to such an extent that they cannot be removed (completely) during the normal exhaust and bake operation.
  • the water vapor may hydrolize the silicate binder for the graphite funnel coating and produce materials which combine with hydrocarbons and/or carbon dioxide from the frit seal to produce stable oxygen-containing compounds. These compounds may be broken down during tube operation, by electron bombardment and/or other causes, and produce gases which cause a large increase in the rate of depletion of the getter sorption capacity, which greatly reduces the operating life of the tube.
  • the envelope may be flushed with any dry non-contaminating gas, such as nitrogen or warm air. After flushing, the envelope may be temporarily closed, by capping or plugging, to maintain a non-contaminating gas filling therein during a subsequent hold period prior to gun insertion and exhaust.
  • any dry non-contaminating gas such as nitrogen or warm air.
  • FIG. 1 is a flow-chart showing a method comprising the invention.
  • FIG. 2 is a side view of a cathode ray tube envelope with gas flushing apparatus.
  • FIG. 3 is an enlarged detail of a portion of the flushing tubing of FIG. 2.
  • FIG. 4 is an enlarged axial sectional view of a portion of the tube neck in FIG. 2.
  • FIG. 5 is a side view of a tube envelope capped off for bolding or storage.
  • a glass panel may be frit-sealed to a glass funnel, in step A, by the method described in Claypoole US. Pat. No. 2,889,952 to form the tube envelope.
  • the mask assembly Prior to frit-seal, the mask assembly has been mounted in the panel, the faceplate has been screened, aluminized and baked, and the funnel has been provided with its internal conducting (graphite) coating.
  • the funnel is made up of a cone portion sealed at its larger end to the panel and a cylindrical neck portion joined to a smaller end of the cone and having its other end open to receive the tube stem and electron gun.
  • the envelope is processed to flush the residual atmosphere therefrom and fill it with a non-contaminating gas, step B.
  • This may be done, as shown in FIGS. 2-4, by inserting an elongated tubing 1 and a surrounding resilient stopper 3 into the open end of the neck 5 of a color tube envelope 7 and admitting the gas from a gas source 9 through a valve I0 and the tubing 1.
  • the upper end of the tubing 1 may be formed with apertures 11 for directing the gas in a desired manner, e.g., outwardly.
  • the outer periphery of the stopper 3 is either non-circular or formed with longitudinal grooves 13 to permit the residual gases within the envelope to be flushed out of the envelope by the gas from source 9.
  • the tubing 1 may be eccentric to the stopper to improve the flushing action. It will be understood that the size of the tubing 1, apertures 11 and grooves 13 and the gas pressure of the source 9 should be chosen to produce the desired flushing time. In one apparatus that has been used successfully in making 25 inch rectangular color tubes, the envelope is flushed for approximately 1 minute, and the volume is exchanged a minimum of 3 times.
  • the non-contaminating gas is preferably dry warm air having a dew point of about 30 C., in order to minimize the water vapor present.
  • water vapor alone, without hydrocarbons and carbon dioxide does not appear to produce contamination, and hence, the hydrocarbons and carbon dioxide, and other contaminants, if any, can be satisfactorily flushed out with air (or nitrogen) at room temperature, having a dew point as high as C. Satisfactory tubes have been made experimentally using room temperature air having a dew point of 1 6 C.
  • the envelope is flushed within minutes after it leaves the fritseal lehr, to minimize contamination.
  • this time is not critical, and can be as long as a few hours. It appears that very little contamination occurs within the first hour after frit-seal.
  • the flushing apparatus is removed, and may be replaced by a temporary closure, such as the resilient cap 15 shown in FIG. 5, to maintain the envelope 7 filled with the non-contaminating gas at atmospheric pressure for a relatively long hold period prior to the next manufacturing operation, which is usually combined gun-insertion and stem-sealing (step C). It has been found that envelopes so flushed and capped can be held or stored up to 3 weeks, if necessary or desired, without causing a large increase in the normal rate of depletion of getter sorption capacity during tube life after manufacture.
  • the capping of the flushed envelope may be omitted, since the rate of diffusion of gases into and out ofthe open neck is small.
  • flushing operation is not essential unless the envelope is held substantially longer than the normal two hours between frit-seal and exhaust, incorporation .of the flushing operation in the manufacture of all color tubes manufactured by applicant's assignee is planned, in order to insure that all color tubes manufactured will have adequate gettering capacity during life, whether or not they are held for a period during manufacture.
  • the electron gun and getter may be inserted in the neck 5, and the glass stem (on which the gun is mounted) sealed to the open end of the neck by known methods, e.g., as shown in FIG. 5 of Trax US. Pat. No. 3,063,777.
  • the getter is normally supported on the electron gun and positioned either adjacent to the end of the gun or within the cone portion of the funnel.
  • the envelope may be exhausted and baked in step E, to remove the gas filling introduced by step B, and to de-gas the various electrodes and other internal surfaces, by any known method, e.g., as described in Johnson et al. US. Pat. No. 2,532,3 l5,dated Dec. 5, 1950.
  • step F the manufacture of the color tube is completed by performing the conventional steps of activation of the cathodes, tip-off of the exhaust tubulation, flashing of the getter to produce a gas absorbing coating of getter material (e.g., barium) on the interior surfaces of the tube, ageing of the gun electrodes, and testing, collectively referred to as step F in FIG. 1.
  • getter material e.g., barium
  • the average oxygen gas capacity of the getters in the five tubes in group (1) at the end of l 1 weeks was 5352 111. (liter-microns), as compared to an average of 2704 1 1. at l 1 weeks for the five tubes in group (2).
  • the flushing of the first group of held tubes doubled the average capacity at 1 1 weeks, and hence, greatly increased the potential life of those tubes.
  • the average gas capacity of the getters in group (1) was not substantially less than that of a standard color tube manufactured without flushing or holding.
  • cathode ray tubes each having an envelope comprising a faceplate panel frit-sealed to a funnel; each of said envelopes containing an electron gun, and a getter adapted to absorb gases during the life of the tube; the method comprising the steps of:
  • each of said envelopes is temporarily closed at the end of step (b) to maintain said gas within said envelope.
  • a cathode ray tube having an envelope comprising a faceplate panel frit-sealed to a funnel, said envelope containing an electron gun, and a getter adapted to absorb gases during the life of the tube; the method com prising the steps of:
  • cathode ray tubes each having an envelope comprising a faceplate panel frit-sealed to a funnel; each envelope containing an electron gun, and a getter adapted to absorb gases during the life of the tube; the method comprising the steps of:

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US959A 1970-01-06 1970-01-06 Method of manufacture of cathode ray tubes having frit-sealed envelope assemblies Expired - Lifetime US3658401A (en)

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US95970A 1970-01-06 1970-01-06

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US (1) US3658401A (ja)
JP (1) JPS5019903B1 (ja)
DE (1) DE2100245A1 (ja)
FR (1) FR2075947B1 (ja)
GB (1) GB1289931A (ja)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932011A (en) * 1974-06-05 1976-01-13 Rca Corporation Conditioning partially-completed CRT bulb assembly for storage and/or transit
US4213663A (en) * 1978-12-26 1980-07-22 Rca Corporation Wet carbon-dioxide treatment of partially-completed CRT
US4493668A (en) * 1983-01-17 1985-01-15 Rca Corporation Method for combined baking-out and panel-sealing of a partially-assembled CRT
US4938727A (en) * 1988-02-01 1990-07-03 Gte Products Corporation Method of manufacturing a glow discharge starter
US6093072A (en) * 1998-05-26 2000-07-25 Micron Technology, Inc. Loading process to provide improved vacuum environment
US6114694A (en) * 1997-03-25 2000-09-05 Nec Corporation Device having field emission type cold cathode and vacuum tank exhausting method and system in the same
WO2001012942A1 (en) * 1999-08-18 2001-02-22 The University Of Sydney Evacuated glass panel having a getter

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4048545A (en) * 1976-11-24 1977-09-13 Union Carbide Corporation Cathode ray tube processing
JPS5480669A (en) * 1977-12-09 1979-06-27 Sony Corp Manufacture for cathode ray tube and ventilation unit used for its sintering process
US4923423A (en) * 1989-06-30 1990-05-08 Rca Licensing Corporation Integrated thermal processing for kinescopes

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2091863A (en) * 1935-04-08 1937-08-31 Kessler Jacob Process of making commutator blocks for cathode ray tubes
US2334718A (en) * 1941-12-27 1943-11-23 Sylvania Electric Prod Lamp exhaust method
US2520190A (en) * 1946-10-24 1950-08-29 Philips Lab Inc Cathode-ray tube
US2871087A (en) * 1956-02-10 1959-01-27 Westinghouse Electric Corp Method of assembling a color television tube
US3319818A (en) * 1962-05-08 1967-05-16 Corning Glass Works Manufacture of cathode ray tubes for color television
US3388955A (en) * 1965-02-25 1968-06-18 Getters Spa Process for producing within electron tubes,in particular television picture tubes,a thin metallic film capable of sorbing their residual gases
US3432712A (en) * 1966-11-17 1969-03-11 Sylvania Electric Prod Cathode ray tube having a perforated electrode for releasing a selected gas sorbed therein

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2091863A (en) * 1935-04-08 1937-08-31 Kessler Jacob Process of making commutator blocks for cathode ray tubes
US2334718A (en) * 1941-12-27 1943-11-23 Sylvania Electric Prod Lamp exhaust method
US2520190A (en) * 1946-10-24 1950-08-29 Philips Lab Inc Cathode-ray tube
US2871087A (en) * 1956-02-10 1959-01-27 Westinghouse Electric Corp Method of assembling a color television tube
US3319818A (en) * 1962-05-08 1967-05-16 Corning Glass Works Manufacture of cathode ray tubes for color television
US3388955A (en) * 1965-02-25 1968-06-18 Getters Spa Process for producing within electron tubes,in particular television picture tubes,a thin metallic film capable of sorbing their residual gases
US3432712A (en) * 1966-11-17 1969-03-11 Sylvania Electric Prod Cathode ray tube having a perforated electrode for releasing a selected gas sorbed therein

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932011A (en) * 1974-06-05 1976-01-13 Rca Corporation Conditioning partially-completed CRT bulb assembly for storage and/or transit
US4213663A (en) * 1978-12-26 1980-07-22 Rca Corporation Wet carbon-dioxide treatment of partially-completed CRT
US4493668A (en) * 1983-01-17 1985-01-15 Rca Corporation Method for combined baking-out and panel-sealing of a partially-assembled CRT
US4938727A (en) * 1988-02-01 1990-07-03 Gte Products Corporation Method of manufacturing a glow discharge starter
US6114694A (en) * 1997-03-25 2000-09-05 Nec Corporation Device having field emission type cold cathode and vacuum tank exhausting method and system in the same
US6093072A (en) * 1998-05-26 2000-07-25 Micron Technology, Inc. Loading process to provide improved vacuum environment
WO2001012942A1 (en) * 1999-08-18 2001-02-22 The University Of Sydney Evacuated glass panel having a getter

Also Published As

Publication number Publication date
FR2075947A1 (ja) 1971-10-15
FR2075947B1 (ja) 1976-01-09
GB1289931A (ja) 1972-09-20
JPS5019903B1 (ja) 1975-07-10
DE2100245A1 (de) 1971-07-15
DE2100245B2 (ja) 1979-03-15

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