US3905079A - Method of manufacturing color selective electrode for color picture tube of black matrix type or the like type - Google Patents

Method of manufacturing color selective electrode for color picture tube of black matrix type or the like type Download PDF

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Publication number
US3905079A
US3905079A US436723A US43672374A US3905079A US 3905079 A US3905079 A US 3905079A US 436723 A US436723 A US 436723A US 43672374 A US43672374 A US 43672374A US 3905079 A US3905079 A US 3905079A
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Prior art keywords
apertures
openings
etching
electrode plate
electron emission
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Expired - Lifetime
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US436723A
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English (en)
Inventor
Hiromi Kanai
Kiyoshi Watanabe
Eiichi Yamazaki
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Hitachi Ltd
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Hitachi Ltd
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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
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/14—Manufacture of electrodes or electrode systems of non-emitting electrodes
    • H01J9/142—Manufacture of electrodes or electrode systems of non-emitting electrodes of shadow-masks for colour television tubes
    • H01J9/144—Mask treatment related to the process of dot deposition during manufacture of luminescent screen

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  • FIG. 2b PRIOR ART FIG. 2b
  • the present invention relates to a method of manufacturing a color selective electrode for a color picture tube effective for obtaining the picture quality of high color purity.
  • a re-etching treatment of the color selective electrode such as a shadow mask is necessary for the case in which it is required for a phosphor screen of a color picture tube to be provided, by means of a photographic technique, with a plurality of phosphor units, e.g. phosphor dots having a diameter smaller than that of the openings in the shadow mask, in particular for the case of color picture tube of the black matrix type or the color picture tube of the post-focussing type.
  • the conventional re-etching process has the essential difficulty that it degrades the performance of the color picture tube by the fact that it reduces the thickness of the shadow mask so that the mechanical strength of the shadow mask is reduced and that the control of the diameter of openings in the shadow mask is difficult.
  • the color picture tube of the postfocussing type to suppress the secondary electron emission from the shadow mask to prevent the deterioration of the color purity due to the scattering of the secondary electrons it is effective to coat the surfaces of the shadow mask with a material of a low secondary electron emission ratio so thatit has been practiced that the surfaces of the shadow mask are coated with graphite or carbon bromide after the re-etching.
  • An object of the present invention is to provide a method of manufacturing a color selective electrode of a color picture tube which overcomes the abovedescribed difficulty.
  • FIGS. la to 1d are cross-sections depicting the steps of a conventional method of manufacturing a shadow mask.
  • FIGS. 2a to 2d are cross-sections depicting the steps of an embodiment of the present invention.
  • an electrode plate 1 has apertures 6 formed therein and is coated with a layer 2 called a blackening film for rust prevention as shown in FIG. 1a. Then, the blackening film 2 is removed by a treatment called pickling as shown in FIG. lb, after which the aperture size is increased by a re-etching to form openings 6 as shown in FIG. 1c. Finally, the electrode plate 1 is coated with a rust preventing blackening film 2' by a chemical treatment to provide a shadow mask 1' as shown in FIG. 1d.
  • the main component of the blackening film 2 is iron oxide which has a high secondary electron emission ratio. Consequently, in the post-focussing type color picture tube, the electrode plate is coated with a secondaryel'ec'tron emission suppressing film instead of the blackening film after the aperture size augmentation,
  • the manufacture of the shadow mask including the re-etching process requires a high degree of technique and yet cannot provide predetermined performance due to the necessity of the control of the aperture size or the shortage of the mechanical strength resulting from the reduction of the thickness of the shadow mask after the re-etching or the necessity of such a difficult process as the application of the secondary electron emission suppressing film.
  • color selective electrode is assumed to be a shadow mask, but any other type of color selective electrode, for example one having stripe openings will likewise do.
  • FIG. 2a parts of the main surfaces of an apertured electrode 1 and walls of apertures 3 in the electrode plate are first covered with an auxiliary film of a material 4 such as a photoresist.
  • the apertures 3 have been formed by an etching treatment.
  • a secondary electron emission suppressing material 5 such as C, CBr, CBr or CBr is applied to the main surfaces of the electrode plate 1 as shown in FIG. 2b by means of, for example, ion plating or electroplating.
  • the material 5 must be resistive to an etchant (e.g., ferric chloride) to be used in a later etching, i.e., re-etching treatment.
  • the thickness of the layer of the material 5 may be 1 4 IL.
  • the material 4 is removed from the electrode plate 1 as shown in FIG. 20.
  • the electrode plate 1 shown in FIG. 2c is subjected to a re-etching treatment to enlarge the apertures 3 to form openings 3a defined by D and D thereby completing a shadow mask as shown in FIG. 2d.
  • the walls of the openings 3a may be further subjected to a rust preventing treatment such as electrolytic polishing, if necessary.
  • the apertures 3 to be enlarged are etched because they are not covered with the etchant-resistive secondary electron emission suppressing film, while the other parts are not etched because of being covered with the secondary electron emission suppressing film, so that the control of the aperture size at the time of the re-etching is unnecessary and no reduction of the thickness of the shadow mask results.
  • a method for manufacturing a color selective electrode for a color picture tube of the type having a phosphor screen provided with a plurality of phosphor units the dimensions of which are smaller than those of openings in the color selective electrode comprising:
  • said electrode plate having two main surfaces communicating with each other through said apertures, said apertures being smaller in dimensions than said openings; covering the walls of said apertures and at least portions of said main surfaces with an auxiliary film to define predetermined dimensions for said openings;
  • said phosphor screen being produced by steps including photographic exposure through said apertures prior to said re-etcliing step.
  • aux--- iliary film is a photoresist material.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US436723A 1973-04-13 1974-01-25 Method of manufacturing color selective electrode for color picture tube of black matrix type or the like type Expired - Lifetime US3905079A (en)

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JP48041397A JPS49130670A (enrdf_load_stackoverflow) 1973-04-13 1973-04-13

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US3905079A true US3905079A (en) 1975-09-16

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JP (1) JPS49130670A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955981A (en) * 1975-01-06 1976-05-11 Zenith Radio Corporation Method of forming electron-transmissive apertures in a color selection mask by photoetching with two resist layers
US4596943A (en) * 1983-01-31 1986-06-24 Tokyo Shibaura Denki Kabushiki Kaisha Shadow mask for a color picture tube

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3663997A (en) * 1970-09-30 1972-05-23 Rca Corp Method for making a kinescope comprising production and treatment of a temporary mask
US3676914A (en) * 1970-05-01 1972-07-18 Zenith Radio Corp Manufacture of shadow mask color picture tube
US3693223A (en) * 1971-12-30 1972-09-26 Zenith Radio Corp Screening process for color cathode-ray tube

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3676914A (en) * 1970-05-01 1972-07-18 Zenith Radio Corp Manufacture of shadow mask color picture tube
US3663997A (en) * 1970-09-30 1972-05-23 Rca Corp Method for making a kinescope comprising production and treatment of a temporary mask
US3693223A (en) * 1971-12-30 1972-09-26 Zenith Radio Corp Screening process for color cathode-ray tube

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955981A (en) * 1975-01-06 1976-05-11 Zenith Radio Corporation Method of forming electron-transmissive apertures in a color selection mask by photoetching with two resist layers
US4596943A (en) * 1983-01-31 1986-06-24 Tokyo Shibaura Denki Kabushiki Kaisha Shadow mask for a color picture tube

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Publication number Publication date
JPS49130670A (enrdf_load_stackoverflow) 1974-12-14

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