US3556627A - Method of making a cathode-ray tube - Google Patents

Method of making a cathode-ray tube Download PDF

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Publication number
US3556627A
US3556627A US633238A US3556627DA US3556627A US 3556627 A US3556627 A US 3556627A US 633238 A US633238 A US 633238A US 3556627D A US3556627D A US 3556627DA US 3556627 A US3556627 A US 3556627A
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United States
Prior art keywords
acid
mount
cathode
ray tube
making
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Expired - Lifetime
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US633238A
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English (en)
Inventor
Takeo Takemoto
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/82—Mounting, supporting, spacing, or insulating electron-optical or ion-optical 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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/485—Construction of the gun or of parts thereof

Definitions

  • This invention relates to a novel and improved method of making a cathode-ray tube and also relates to a cathode-ray tube made thereby.
  • Cathode-ray tubes especially color picture tubes are H generally provided with grid No. 3 and grid No. 4 constituting an electron lens for focusing the electron beam, and in such a tube, a high voltage of more than 20,000 volts is fed to grid No. 4, while a voltage in the order .of
  • another source of the cold emission may sometimes be provided by oxidized portions of bead supports used for supporting the electrodes which are mounted in bead glasses and acted upon by the strong electric field, because those portions of the bead supports exposed to the glass are unavoidably oxidized during mounting of the bead supports in the bead glass.
  • its bead glass or neck tube is charged by the induction due to a high voltage applied to grid No. 4 and the pole-piece cage directly connected to grid No. 4 or by being bombarded by high speed stray electrons.
  • This electric charge becomes unstable by being alfected by the cold emission electrons or by the secondary electrons emitted from the electrodes and is subject to variation with time.
  • This variation in the electric charge causes a corresponding variation in the potential distribution in the main electron lens constituted by the two electrodes, that is, grid No. 3 and grid No. 4.
  • stainless steel is a chemically stable metal, but when microscopically examined, it can be seen that its surface is covered with an oxidized surface film of chromium which is one of the metals contained in the steel composition, and this oxidized surface film which is thickened when heated or left to stand for an extended period of time in air is considered to provide a source of cold emission.
  • Another object of the present invention is to provide a cathode-ray tube made by the method according to the invention.
  • a method of making an electron gun for a cathoderay tube comprising the steps of firmly securing a plurality of electrodes forming an electron gun of a cathode-ray tube to bead glasses by a plurality of bead supports to obtain a mount, immersing said mount in an acid etching solution for a time sufficient to substantially completely remove an oxidized layer formed on the surface of the electrodes, then rinsing said mount having been treated with said acid etching solution, and fixing heaters and cathodes to said mount.
  • a method of making a cathode-ray tube comprising the steps of sealing an electron gun made by the above method in a bulb having a phosphor screen, and exhausting the interior of said bulb.
  • a cathode-ray tube having at least one electron gun therein, said electron gun comprising a mount formed by firmly securing a plurality of electron gun electrodes to a 'bead glass by a plurality of bead supports, said mount being then immersed in an acid etching solu tion for the substantially complete removal of an oxidized layer from its surface, and heaters and cathodes being assembled with said mount.
  • the color picture tube includes a neck tube 1, a heater 2, a cathode 3, a grid No. 1 4, a grid No. 2 5, a grid No. 3 6 and a grid No. 4 7 of stainless steel, and a pole-piece cage 8.
  • the electron gun structure in the cathode-ray tube described above is made in a manner that the grid No. 1 4, grid No. 2 5, grid No. 3 6 and grid No. 4 7 are fixed to bead glasses 9 by respective bead supports #10, 11, 12 and 13 of stainless steel and a mount so assembled is then subjected to an acid treatment.
  • the mount may be immersed for a period of about 1 minute in a strong acid solution which is prepared by mixing a few percent of hydrofluoric acid, by Weight based on the undermentioned mixture, with a mixture consisting of 1 part by weight of nitric acid and 6 parts by weight of water and is heated to a temperature in the order of 50 C.
  • the above acid treatment may be made by use of acid solutions other than the mixed acid consisting of nitric acid and hydrofluoric acid referred to above.
  • a mixed acid solution suitable for the acid treatment may be prepared by mixing hydrochloric acid (specific gravity 1.12), a hydrogen peroxide solution and water in a weight ratio of 1.2: 13:75 and adding to the above mixture 0.2% by weight potassium phosphate as an inhibitor, and the mount may be treated for several minutes at a treatment temperature in the range of 30 to C.
  • a mixed acid solution may be prepared by mixing hydrochloric acid (specific gravity 1.12), a 30% hydrogen peroxide solution, hydrofluoric acid and Water in a weight ratio of 1.1:1.5:0.6 :6.8, and the mount may be treated for several minutes at a treatment temperature in the range of 28 to 33 C.
  • a mixed acid solution may be prepared by mixing hydrochloric acid (specific gravity 1.12), sulfuric acid (specific gravity 1.82), chromic anhydride and water in a weight ratio of 0.3:0.4:0.05:9.3 and annexing to the above mixture 0.1 to 0.2% by weight potassium phosphate as an inhibitor, and the mount may be treated for several minutes at a treatment temperature in the range of to C.
  • a thin oxidized layer with a thickness in the order of one or two molecular layers might remain on the surface of each electrode even after the acid treatment described above, but such layer will be exhausted soon and would hardly act as a source of cold emission.
  • the mount is rinsed and is assembled together with the heater 2 and the cathode 3.
  • the assembly thus obtained is immediately sealingly mounted in a bulb (not shown) and the bulb is then exhausted.
  • the cathode-ray tube thus made is free from the arcing, cold emission phenomenon,
  • a liquid used for the rinsing of the mount has desirably such a nature that it would not re-oxidize the electrode surface, and in this respect, pure water is most preferred;
  • the prominent effects obtainable by the acid treatment as described above will be described in more detail.
  • the first effect resides in that the stainless steel surface is smoothed out by the etching of convex parts of surface unevenness and is rendered less liable to be oxidized by virtue of the reduced overall surface area.
  • the second effect is derivable from the fact that the surface of the stainless steel after the above treatment is merely covered with an extremely thin oxidized layer with a thickness in the order of one to two molecular layers. Therefore, even if the cold emission might emanate from such oxidized layer, the source of the cold emission would be exhausted in a quite short time and can not continue the emanation of the cold emission.
  • the mount having been subjected to the acid treatment as described above should be kept in an oxidization-free state, and after having been mounted in a bulb to form a cathoderay tube, the bulb should be exhausted as soon as possible to keep the interior of the bulb in a high vacuum state to thereby further enhance the effect of inhibition from oxidization.
  • electrolytic polishing may be employed in lieu of the acid treatment to effect the cleaning of the surface of the stainless steel, but according to our experiment, the effect attained by the electrolytic polishing was not so marked compared with the effect attained by the acid treatment.
  • a color picture tube has been referred to in the foregoing description, but it will be understood that the present invention is also applicable to other cathode-ray tubes, for example, black and white picture tubes.
  • the etching solution usable in the present invention is in no way limited to the specific etching solutions referred to in the above. It will also be understood that the duration of the acid treatment may be suitably adjusted without departing from the spirit and scope of the present invention.
  • the foregoing description has referred to a mount of the type having Nos. 1 to 4 electrodes therein, it will be understood that the present invention is likewise effectively applicable to a mount of the type having Nos. 1 to 5 electrodes therein, and leads for these electrodes may be treated together with the electrodes in the stepof the acid treatment.
  • a method of making an electron gun for a cathoderay tube comprising the steps of individually cleaning a plurality of grid electrodes to remove foreign matter therefrom, firmly securing said plurality of grid electrodes forming said electron gun of said cathode-ray tube to bead glass by a plurality of bead supports to form a mount, immersing said mount in an acid etching solution for a time sufficient to substantially remove oxidiz'ed layers existing on the surface of said mount, then rinsing said mount which has been treated with said acid etching solution, and thereafter fixing heaters and cathodes to said mount.
  • a method of making an' electron gun fora cathoderay tube according to claim l in which said acid etching solution is prepared by adding several percent .by weight hydrofluoric acid to a mixture of nitric acid .and water mixed in a weight ratio of about 1:6 and is heated to a temperature of about 50 C., and said mount is immersed in said etching solution for about 1 minute.
  • said acid etching solution is a mixture of hydrochloric acid having a specific gravity of 1.12, a 30% hydrogen peroxide solution, hydrofluoric acid and water mixed in a weight ratio of 1.1:1.5:0.6:6.8 and is heated to a temperature of 28 to 33 C., and said mount is immersed in said etching solution for several minutes.

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  • Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
US633238A 1966-05-13 1967-04-24 Method of making a cathode-ray tube Expired - Lifetime US3556627A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP41029937A JPS4820945B1 (fr) 1966-05-13 1966-05-13

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US3556627A true US3556627A (en) 1971-01-19

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US (1) US3556627A (fr)
JP (1) JPS4820945B1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2509090A1 (fr) * 1981-07-02 1983-01-07 Rca Corp Procede de fabrication d'un tube a rayons cathodiques
US4406639A (en) * 1981-09-29 1983-09-27 Rca Corporation Wet processing of electrodes of a CRT to suppress afterglow
US5460559A (en) * 1993-07-20 1995-10-24 U.S. Philips Corporation Cathode ray tube
EP1176621A3 (fr) * 2000-07-24 2003-03-26 Sony Corporation Canon à électrons et son procédé de fabrication, et tube à rayons cathodiques

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5280056U (fr) * 1975-12-11 1977-06-15

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2509090A1 (fr) * 1981-07-02 1983-01-07 Rca Corp Procede de fabrication d'un tube a rayons cathodiques
US4406639A (en) * 1981-09-29 1983-09-27 Rca Corporation Wet processing of electrodes of a CRT to suppress afterglow
US5460559A (en) * 1993-07-20 1995-10-24 U.S. Philips Corporation Cathode ray tube
EP1176621A3 (fr) * 2000-07-24 2003-03-26 Sony Corporation Canon à électrons et son procédé de fabrication, et tube à rayons cathodiques

Also Published As

Publication number Publication date
JPS4820945B1 (fr) 1973-06-25

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