US3922049A - Method of degassing a cathode-ray tube prior to sealing - Google Patents

Method of degassing a cathode-ray tube prior to sealing Download PDF

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Publication number
US3922049A
US3922049A US454158A US45415874A US3922049A US 3922049 A US3922049 A US 3922049A US 454158 A US454158 A US 454158A US 45415874 A US45415874 A US 45415874A US 3922049 A US3922049 A US 3922049A
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US
United States
Prior art keywords
cathode
envelope
mount assembly
heater
frequency energy
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
US454158A
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English (en)
Inventor
Frank Stanley Sawicki
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.)
RCA Licensing Corp
Original Assignee
RCA Corp
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 RCA Corp filed Critical RCA Corp
Priority to US454158A priority Critical patent/US3922049A/en
Priority to MX100146U priority patent/MX2991E/es
Priority to CA221,486A priority patent/CA1022227A/en
Priority to IT21066/75A priority patent/IT1034121B/it
Priority to ES435720A priority patent/ES435720A1/es
Priority to AU79257/75A priority patent/AU496231B2/en
Priority to BR1624/75A priority patent/BR7501624A/pt
Priority to FR7508530A priority patent/FR2273365B1/fr
Priority to PL1975178945A priority patent/PL97861B1/pl
Priority to GB11898/75A priority patent/GB1489644A/en
Priority to BE154624A priority patent/BE827021A/xx
Priority to NL7503481A priority patent/NL7503481A/xx
Priority to ZA00751834A priority patent/ZA751834B/xx
Priority to DE2512906A priority patent/DE2512906C3/de
Priority to SU752117531A priority patent/SU663335A3/ru
Priority to JP3666875A priority patent/JPS555810B2/ja
Application granted granted Critical
Publication of US3922049A publication Critical patent/US3922049A/en
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
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
    • 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
    • H01J9/385—Exhausting vessels

Definitions

  • ABSTRACT [31] A L N 454 153 A method for making a cathode-ray tube including baking the envelope and mount assembly and simultaneously exhausting gases from the envelope. and then [52] S f, 6/19; 316/30 sealing (tipping off) the exhausted emelope. During i511 9/18 the baking and exhausting of the tube. the following 8] field Search 316/]71 steps are carried out first sequentially and then simul 3l6/30- 13 53/88 taneously: (a) applying radio-frequency energy to the mount assembly and (b) passing electric current [56] References and through the cathode heater.
  • This invention relates to a noveLmethod for degassing a cathode-ray tube, particularly the mount-assembly structures thereof, during the simultaneous exhausting and baking steps for making the tube. prior to sealing the tube.
  • a luminescent screen and various conductive coatings are applied to various internal surfaces of the envelope which includes a neck portion.
  • a mount assembly supported on a glass stem and including the electron gun or guns, is sealed into the neck portion of the tube.
  • the tube which is open to the atmosphere through a glass tubulation connected to the stem. is baked at about 300 to 450C and is simultaneously exhausted to a relatively low pressure. Then, the tube is tipped off; that is, the tubulation is sealed. Apparatus for carrying out this process is described in the prior art; for example, U.S. Pat. No. 2,532,3l5 to M. E. Johnson et al and U.S. Pat. No. 3,115,732 to I. F. Stewart.
  • radio-frequency energy at about l.0 to l.5 magahertz is applied to the mount assembly to degas the mount structures by heating. Then, electric current is passed through the cathode heater to heat the cathode to decompose the cathode coating material and to degas the cathode structure. It has been suggested to perform these latter two steps either sequentially or simultaneously.
  • sequential application of radio-frequency energy and heater current does not produce tubes having the highest cathode emission characteristics. Simultaneous application of radio-frequency energy and heater current frequently results in an increase in the proportion oftubes that is rejected for unsatisfactory performance.
  • radio-frequency energy and heater current are first applied sequentially and then are applied simultaneously to the mount assembly and cathode heater respectively during the simultaneous baking and exhausting steps prior to sealing.
  • the initial sequential processing performs the previous functions of degassing the structures and decomposing the cathode coating.
  • the subsequent simultaneous processing raises the temperatures of all the structures above 450C to again outgas them but in a manner that prevents redeposition of materials released from other structures.
  • the finished tubes exhibit higher emission currents from the cathodes and there is a high yield of satisfactory tubes.
  • FIGURE is a schematic plan view of an apparatus for practicing the novel method showing the relative locations of the heating zones and the process ing positions.
  • the invention may be practiced in the continuous apparatus disclosed in U.S. Pat. No. 2,532,315 to M. E. Johnson et al.
  • the apparatus shown in the sole FIG- URE is similar to the apparatus described in the Johnson et al patent; however, the apparatus employs the improved cart disclosed in U.S. Pat. No. 3.1 15,732 to J. F. Stewart.
  • the apparatus shown in the sole FIGURE comprises a train of carts A moving counter clockwise along a closed, elongated loop.
  • a tunnel oven B of a generally U-shaped plan is located over a portion of the train of carts in a manner to enclose the tubes being processed.
  • the tunnel is divided into 28 zones that are numbered I through 28. Except for zones 13 and 14, the zones are straight and of equal length of about 10 feet.
  • Bus bars delivering electrical energy for processing the tubes are located along zones 15 through 24 and are divided into processing positions C numbered 1 through 42. The processing positions are each about 28 inches in length.
  • a sequence of 25 V-size color television picture tubes (assembled but not yet exhausted and sealed) is loaded successively, one tube to a cart, onto the train of carts A passing continuously into and through the tunnel oven B of this apparatus at the rate of about 54 to carts per hour.
  • Each tube includes an envelope having a faceplate, a funnel portion, and a glass-neck portion.
  • the neck portion is closed at one end by a glass stem having metal stem leads and a glass tubulation extending outwardly therefrom.
  • the metal stem leads also extend inwardly and support the mount assembly of the tube.
  • the mount assembly includes the electron guns of the tube.
  • Each gun includes an indirectly heated thermionic cathode having a heated side and an emitting side, a cathode heater spaced from the heated side of the cathode, and a grid (GI) spaced from the emitting side of the cathode.
  • the tubulation is connected to equipment for exhausting the tube of gas, and the stem leads are connected so that a current may be passed through the cathode heater.
  • a coil is disposed about the neck so that radio-frequency energy may be applied to the mount assembly of the tube.
  • Each cart passes through the tunnel oven B in about two to three hours.
  • the temperatures of the zones increase from about room temperature (at zone 1) to about 440C (at zone 11) and then decrease to about C (at zone 28).
  • pumps are removing gas from the interior of each tube through the exhaust tubulation extending from the stem that is sealed into the tube neck.
  • radio-frequency energy at about 1.0 to L5 megahertz is applied to the mount assembly according to the schedule in the TABLE. No radiofrequency energy is applied at processing positions 19 through 23.
  • a cathode-heater current of about 1.] amp is passed through the cathode heaters with an applied voltage of about 12.0 volts dc at position 23.
  • the applied voltage is higher than the normal operating voltage of about 6.3 volts, and causes the cathode temperature to rise about to 250 C above the normal operating temperatureof about 800C.
  • both radiofrequency energy and cathode-heater current are applied simultaneously to the mount assembly and the cathode heaters respectively according to the schedule in the TABLE.
  • the heating effect on the cathode, on grid No. 1 (GI) and grid No. 3 (G3) of the tube at the various positions is also shown in the TABLE.
  • heat is applied to melt a portion of the tubulation and to seal (tip-off) the tube interior from the atmosphere.
  • the prior factory process follows the schedule shown in the TABLE except that the radio-frequency energy (rf) and the cathode heater current (If) are both zero at positions 24 through 28.
  • the simultaneous application of radio-frequency energy and cathode-heater current at positions 24 through 28 raises the temperature of the cathode and the grid No. 1 above 450C, and preferably above 600C.
  • This additional high-temperature heating is believed to clean and degas the surfaces of the various structures without causing lifting of the coating on the cathode.
  • Results have shown an increase in cathode-emission current in the finished tubes of about 8 percent, and a reduction of reject tubes due to lifted cathode coatings and other causes, as compared with the prior process which employs only the sequential application of radio-frequency energy and cathodeheater current.
  • the novel method is not limited to any of these.
  • the method may be practiced with different schedules and various tubes and on a variety of machines.
  • the invention may be practiced on a stationary machine with periodic tube processing.
  • the novel method does require first the sequential application of radio-frequency energy and cathode-heater current, followed by the simultaneous application of both radio-frequency energy and cathode-heater current to the mount assembly and cathode heater respectively, and preferably is conducted for at least 2 minutes.
  • a cathode-ray tuhe comprising an envelope and a mount assembly including at least one cathode and a heater therefor sealed in said envelope, said method including the steps of baking said envelope and mount assembly at about 300 to 450C and simultaneously exhausting gases from said envelope and then sealing said envelope,
  • the steps during said baking and exhausting of said envelope comprising first l sequentially and then (2) simultaneously (a) applying radio-frequency energy to said mount assembly and (b) passing electric current through said heater, whereby said simultaneous application step (2) heats said mount assembly including said cathode above 450C.
  • a cathode-ray tube comprising an envelope having a neck portion, a mount assembly sealed in said neck portion, said mount assembly including at least one indirectly-heated thermionic cathode having an emitting side and a heated side. a grid spaced from said emitting side of said cathode and a heater spaced from the heated side of said cathode, and an exhaust tubulation extending from said envelope,
  • said method including the steps of baking said envelope and mount assembly at about 300 to 450C. simultaneously exhausting gases from inside said envelope through said exhaust tubulation and, in sequence during said baking and exhausting steps:

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US454158A 1974-03-25 1974-03-25 Method of degassing a cathode-ray tube prior to sealing Expired - Lifetime US3922049A (en)

Priority Applications (16)

Application Number Priority Date Filing Date Title
US454158A US3922049A (en) 1974-03-25 1974-03-25 Method of degassing a cathode-ray tube prior to sealing
MX100146U MX2991E (es) 1974-03-25 1975-03-03 MEJORAS A UN METODO PARA FABRICAR TUBOS DE RAYOS CATODICOS".,"La presente inveción se refiere a mejoras a un método para fabricar tubos de rayos catódicos que comprenden de una envolvente y un conjunto de montaje que incluye al menos un cátodo y un calentador para el mismo sellados en la envolvente; y el método incluye las etapas de hornear la envolvente y el cojunto de montaje a aproximadamente 300°C a 450°C y simultáneamente descargar los gases de la envolvente antes de sellar la envolvente; caracterizadas en que, durante las etapas simultáneas de horneado y de descarga, se aplica energía de radio-frecuencia al conjunto de montaje y se aplica corriente eléctrica a através del calentador, en aplicaciones secuenciales y luego en aplicaciones simultáneas.
CA221,486A CA1022227A (en) 1974-03-25 1975-03-05 Degassing a cathode ray tube prior to sealing
IT21066/75A IT1034121B (it) 1974-03-25 1975-03-07 Metodo di fabricazione di un tubo a raggi catodici
ES435720A ES435720A1 (es) 1974-03-25 1975-03-18 Un metodo para la fabricacion de un tubo de rayos catodi- cos.
BR1624/75A BR7501624A (pt) 1974-03-25 1975-03-19 Processo de fabricacao de um tubo de raios catodicos
FR7508530A FR2273365B1 (it) 1974-03-25 1975-03-19
AU79257/75A AU496231B2 (en) 1974-03-25 1975-03-19 Degassing a cathode ray tube prior to sealing
PL1975178945A PL97861B1 (pl) 1974-03-25 1975-03-20 Sposob odgazowania lampy kineskopowej
GB11898/75A GB1489644A (en) 1974-03-25 1975-03-21 Method for making a cathode-ray tube
BE154624A BE827021A (fr) 1974-03-25 1975-03-21 Procede pour la fabrication de tubes cathodiques
NL7503481A NL7503481A (nl) 1974-03-25 1975-03-24 Werkwijze voor het vervaardigen van een kathode- straalbuis en kathodestraalbuis vervaardigd volgens deze werkwijze.
ZA00751834A ZA751834B (en) 1974-03-25 1975-03-24 Degassing a cathode ray tube prior to sealing
DE2512906A DE2512906C3 (de) 1974-03-25 1975-03-24 Verfahren zur Fertigung einer Bildwiedergaberöhre
SU752117531A SU663335A3 (ru) 1974-03-25 1975-03-25 Способ вакуумной обработки электроннолучевой трубки
JP3666875A JPS555810B2 (it) 1974-03-25 1975-03-25

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US454158A US3922049A (en) 1974-03-25 1974-03-25 Method of degassing a cathode-ray tube prior to sealing

Publications (1)

Publication Number Publication Date
US3922049A true US3922049A (en) 1975-11-25

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ID=23803543

Family Applications (1)

Application Number Title Priority Date Filing Date
US454158A Expired - Lifetime US3922049A (en) 1974-03-25 1974-03-25 Method of degassing a cathode-ray tube prior to sealing

Country Status (15)

Country Link
US (1) US3922049A (it)
JP (1) JPS555810B2 (it)
BE (1) BE827021A (it)
BR (1) BR7501624A (it)
CA (1) CA1022227A (it)
DE (1) DE2512906C3 (it)
ES (1) ES435720A1 (it)
FR (1) FR2273365B1 (it)
GB (1) GB1489644A (it)
IT (1) IT1034121B (it)
MX (1) MX2991E (it)
NL (1) NL7503481A (it)
PL (1) PL97861B1 (it)
SU (1) SU663335A3 (it)
ZA (1) ZA751834B (it)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3112001A1 (de) * 1980-03-26 1982-02-18 RCA Corp., 10020 New York, N.Y. "verfahren zum verdampfen von gettermaterial in einer aufeinanderfolge von kathodenstrahlroehren"
DE3224790A1 (de) * 1981-07-02 1983-03-10 RCA Corp., 10020 New York, N.Y. Verfahren zur herstellung einer kathodenstrahlroehre
US4410310A (en) * 1981-04-23 1983-10-18 Rca Corporation Degassing a CRT with modified RF heating of the mount assembly thereof

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54111750A (en) * 1978-02-22 1979-09-01 Hitachi Ltd Manufacture for cathode ray tube
DE2941422A1 (de) * 1979-10-12 1981-04-23 Calor-Emag Elektrizitäts-Aktiengesellschaft, 4030 Ratingen Verfahren zum evakuieren einer vakuumschalterroehre
JPS6230769U (it) * 1985-08-09 1987-02-24
DE3625803A1 (de) * 1986-07-30 1988-02-04 Ifr Ingenieurbuero Fuer Regelu Verfahren zur evakuierung der atmosphaere aus vakuumgefaessen, insbesondere aus elektronen- oder fernsehbildroehren, und anlage zur durchfuehrung des verfahrens
JPS63198240A (ja) * 1987-02-10 1988-08-16 Sony Corp 抵抗体の製法
JPH01289049A (ja) * 1988-05-17 1989-11-21 Toshiba Corp 陰極線管の製造方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532315A (en) * 1949-04-02 1950-12-05 Eastman Kodak Co Apparatus and process for evacuating electronic tubes and the like

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3115732A (en) * 1961-09-26 1963-12-31 Rca Corp Apparatus for processing cathode ray tubes
US3441333A (en) * 1967-09-26 1969-04-29 Nat Video Corp Method of manufacturing cathode ray tube

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532315A (en) * 1949-04-02 1950-12-05 Eastman Kodak Co Apparatus and process for evacuating electronic tubes and the like

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3112001A1 (de) * 1980-03-26 1982-02-18 RCA Corp., 10020 New York, N.Y. "verfahren zum verdampfen von gettermaterial in einer aufeinanderfolge von kathodenstrahlroehren"
US4335926A (en) * 1980-03-26 1982-06-22 Rca Corporation Method for vaporizing getter material in a succession of cathode-ray tubes
US4410310A (en) * 1981-04-23 1983-10-18 Rca Corporation Degassing a CRT with modified RF heating of the mount assembly thereof
DE3224790A1 (de) * 1981-07-02 1983-03-10 RCA Corp., 10020 New York, N.Y. Verfahren zur herstellung einer kathodenstrahlroehre
US4406637A (en) * 1981-07-02 1983-09-27 Rca Corporation Processing the mount assembly of a CRT to suppress afterglow

Also Published As

Publication number Publication date
DE2512906A1 (de) 1975-10-09
BE827021A (fr) 1975-07-16
CA1022227A (en) 1977-12-06
AU7925775A (en) 1976-09-23
BR7501624A (pt) 1975-12-23
FR2273365B1 (it) 1978-12-29
DE2512906C3 (de) 1984-10-18
ES435720A1 (es) 1976-12-16
JPS50131452A (it) 1975-10-17
GB1489644A (en) 1977-10-26
FR2273365A1 (it) 1975-12-26
ZA751834B (en) 1976-02-25
JPS555810B2 (it) 1980-02-09
NL7503481A (nl) 1975-09-29
IT1034121B (it) 1979-09-10
DE2512906B2 (de) 1977-08-11
MX2991E (es) 1980-01-23
SU663335A3 (ru) 1979-05-15
PL97861B1 (pl) 1978-03-30

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Legal Events

Date Code Title Description
AS Assignment

Owner name: RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, P

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:RCA CORPORATION, A CORP. OF DE;REEL/FRAME:004993/0131

Effective date: 19871208