US3688359A - Method for producing a composite shadow mask - Google Patents

Method for producing a composite shadow mask Download PDF

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Publication number
US3688359A
US3688359A US68601A US3688359DA US3688359A US 3688359 A US3688359 A US 3688359A US 68601 A US68601 A US 68601A US 3688359D A US3688359D A US 3688359DA US 3688359 A US3688359 A US 3688359A
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United States
Prior art keywords
shadow mask
electrode
lens
lens electrode
composite
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Expired - Lifetime
Application number
US68601A
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English (en)
Inventor
Mitsuru Oikawa
Shozo Tamura
Tadao Okabe
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Hitachi Ltd
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Hitachi Ltd
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Filing date
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
    • H01J29/80—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching
    • H01J29/81—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching using shadow masks
    • 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

Definitions

  • the present invention relates to a shadow mask having a converging action upon an electron beam, and more particularly to a method for fabricating a composite shadow mask in which two electrodes, one of which is formed of a mask-like electrical conductor, are superposed with an insulating material interposed therebetween, between which a slight voltage is impressed so that electron lenses may be formed at the beam apertures of a resulted shadow mask.
  • each beam aperture of the shadow mask may serve as an electron lens.
  • One of these electrodes may be a shadow mask electrode having the same construc tion as that of a conventional shadow mask and the other is a shadow mask lens electrode comprising a mesh electrode or an electrode having a great number of tiny holes which forms with the shadow mask electrode an electron lens.
  • the potential given to the shadow mask electrode is slightly lower than that given to the shadow mask lens electrode.
  • a shadow mask having such a construction as described above can add to the improvement not only in the beam utilization factor, i.e. the brightness of picture reproduced, but also to an improvement in color purity and resolution.
  • the shadow mask has several advantages as described above, but it is extremely difficult from the practical fabricating point of view to insert an insulating material between the shadow mask electrode and the shadow mask lens electrode, in particular the mesh like conductive electrode, without filling up some of the many beam apertures of the shadow mask with insulating material. Moreover, the electrification of the insulating material also adversely affects the electron beam, thus making difficult the realization of the proposed shadow mask.
  • a shadow mask lens electrode in the form of a mesh electrode is coated with an insulating material, then the portions of the coating insulating material are removed from the shadow mask lens electrode where the beam apertures of a conventional shadow mask will lie when the coated lens electrode and the shadow mask electrode are combined together, and finally the shadow mask electrode and the shadow mask lens electrode are combined together after the partial removal of the insulating material to produce a shadow mask so designed as to converge the electron beam passing therethrough.
  • FIG. 1 is a cross sectional view of a shadow mask made according to this invention, which will have a converging action upon electron beam, and
  • FIG. 2 is a plan view taken along the line IIII of FIG. 1.
  • numeral 1 shows a shadow mask electrode
  • a shadow mask lens electrode is designated at 2
  • an insulating material layer 3 is provided over said shadow mask lens electrode 2
  • numerals 4 and 5 indicate beam apertures provided respectively in said shadow mask electrode 1 and said shadow mask lens electrode 2.
  • the composite shadow mask as described above is disposed adjacent to the phosphor dot screen (not shown) between the phosphor dot screen and the electron gun (not shown) and a voltage, for example, of l KV is applied between said shadow mask electrode 1 and said shadow mask lens electrode 2 in the conventional manner. Then, every beam aperture (constituted by beam apertures 4 and 5) of the shadow mask (constituted by shadow mask electrode 1 and shadow mask lens electrode 2 and hereafter referred to as composite shadow mask) forms an electron lens. And the electron lens thus formed acts to converge the electron beam passing through the beam aperture toward the center axis of the aperture.
  • the insulating layer 3 serves to support said shadow mask lens electrode 2 on said shadow mask electrode 1 in an insulated condition.
  • the lens electrode 2 may be formed of a mesh of electric conductors, i.e., a woven, knitted, expanded metal, or a metal plate having a great number of holes, the interstitial dimensions or the hole dimensions of which are small compared to the aperture dimensions of the shadow mask electrode.
  • the first step of fabricating the composite shadow mask is to coat a mesh conductor with an insulating layer such as made of, for example, glass.
  • a mesh conductor is, for example, constructed with stainless steel or tungsten wire having a diameter of the mesh conductor comprising 230 meshes.
  • a paste like glass is prepared by dispersing powder of glass into a dispersant, such as nitrocellulose.
  • the mesh conductor is immersed into the paste like glass so that the former is covered with the latter. Thereafter, the mesh conductor with liquid glass coating is dried and the glass powder coating remains over the mesh conductor.
  • a desirable material used for the glass powder may be, for example, an amorphous inorganic substance having a high specific resistance and the softening temperature thereof must be higher than 450C at which the sealing of the picture tube glass envelope is performed.
  • silicate containing a major part of lead oxide, boron oxide or zinc oxide is preferable.
  • the mesh conductor having glass powder coating thereover is subjected to heat treatment at temperatures 550 600C in an electric furnace so that the glass powder fuses. In this way, the structure for the shadow mask lens electrode is fabricated in which the mesh conductor is completely embedded in the glass insulating layer.
  • the thus furnished structure is set on a mold having the same radius of curvature as its respective shadow mask electrode, then the structure is pressed into a desired shape while the glass insulating layer is maintained at its softening temperatures, and finally the shaped structure is mounted on and fixed to a mechanically tough frame so designed as to combine it with the associated shadow mask electrode. Further heating and molding is to be carried out after the mounting of the structure on the frame, if desired.
  • the third step of fabricating the composite shadow mask is carried on as follows.
  • a photoresist material which is soluble in an appropriate solvent when exposed to light is applied to one or both side surfaces of the shadow mask lens electrode structure.
  • the lens electrode structure treated with the photoresist material is exposed to light with the shadow mask electrode masking it from the light. Accordingly, only the portions of the photoresist material lying beneath the beam apertures are exposed to the light and therefore those portions can be removed by a suitable developing treatment using such a solvent as aforementioned. It is preferable, in order to achieve the exposure with a great accuracy, that a d.c. voltage of about 1 KV should be applied between the shadow mask electrode and the shadow mask lens electrode during exposure so as to cause both the electrodes to be attracted to each other.
  • the electrostatic attraction between the electrodes does not bring about such an adverse result, for example, as cracks in the glass coating on the mesh conductor, i.e., the shadow mask lens lens electrode, since the shadow mask electrode and the lens electrode structure are kept in close contact with each other by means of the combining frame.
  • the shadow mask lens electrode structure after the developing treatment in the third step is first treated with an erodent such as fluoric acid or nitric acid so that the glass coating on the mesh con ductor, i.e. the shadow mask lens electrode is partially removed where the light hit the lens electrode structure through the beam apertures of the shadow mask electrode during exposure.
  • the mesh conductor, i.e. the shadow mask lens electrode is made of stainless steel or tungsten as described above and is not dissolved in the erodent such as fluoric acid or nitric acid which dissolves the glass coating.
  • the shadow mask lens electrode structure thus prepared is combined with the associated shadow mask electrode so that a composite shadow mask having a converging action upon the electron beam may be produced.
  • the shadow mask lens electrode structure and its associate shadow mask electrode are arranged to be kept in close contact with each other.
  • the shadow mask lens electrode is coated with an insulating glass and no specific insulation layer between the lens electrode and the shadow mask electrode is necessary. This will add to simplicity in fabricating a composite shadow mask of the type as described above. If an insulating layer is provided on the shadow mask electrode, as is the case with the conventional composite shadow mask, then the insulating layer will be broken on account of temperature variations since the thermal expansion of the insulating layer is different from that of the shadow mask electrode. The composite shadow mask according to the present invention never suffers from such a problem relating to the different coefficients of thermal expansion. Moreover, according to the present method, the diameter of each beam aperture of the shadow mask lens electrode structure, i.e.
  • each eroded area corresponding to each beam aperture of the shadow mask electrode can be chosen large enough as desired by controlling, for example, the time of erosion.
  • the collision of the electron beam against the insulation layer can therefore be eliminated so that the layer is free from being electrified. This fact will also add to the merits of this invention.
  • a method for fabricating a composite shadow mask having a shadow mask electrode and a mesh like shadow mask lens electrode covered with an insulating layer except for portions corresponding to aperture portions of the shadow mask electrode comprising the steps of: coating a mesh like electrical conductor used for the shadow mask lens electrode with a paste of glass-like material which is prepared by dispersing in a dispersant an inorganic material having a high specific resistance; heating said glass-like material to a temperature at which said glass-like material is fused and drying the same to make the insulating layer thereby forming a shadow mask lens electrode structure; moulding said lens electrode structure under heat to shape the same equally to the shape of said shadow mask electrode with which the lens electrode structure is to be associated; applying onto at least one of the two surfaces of said lens electrode structure a photoresist agent which is soluble in an appropriate solvent when exposed to light; exposing said lens electrode structure with said photoresist agent to light through said shadow mask electrode used for a mask for the exposure and subjecting the exposed lens electrode structure to developing treatment to remove the

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US68601A 1969-09-05 1970-09-01 Method for producing a composite shadow mask Expired - Lifetime US3688359A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP44070001A JPS4819107B1 (xx) 1969-09-05 1969-09-05

Publications (1)

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US3688359A true US3688359A (en) 1972-09-05

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Application Number Title Priority Date Filing Date
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US (1) US3688359A (xx)
JP (1) JPS4819107B1 (xx)
NL (1) NL7013126A (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2700135A1 (de) * 1976-01-16 1977-07-28 Philips Nv Verfahren zur herstellung einer farbbildroehre, durch dieses verfahren hergestellte farbbildroehre und vorrichtung zum durchfuehren dieses verfahrens
FR2387507A1 (xx) * 1977-04-15 1978-11-10 Philips Nv
US4164059A (en) * 1976-01-16 1979-08-14 U.S. Philips Corporation Method of manufacturing a color display tube and color display tube manufactured by said method
EP0074738A2 (en) * 1981-09-10 1983-03-23 Kabushiki Kaisha Toshiba Method for making CRT shadow masks
DE3411964A1 (de) * 1983-03-31 1984-10-18 Rca Corp., New York, N.Y. Kathodenstrahlroehre mit fokussierender maske
US4621214A (en) * 1984-04-19 1986-11-04 Rca Corporation Color selection means having a charged insulator portion for a cathode-ray tube
US5226801A (en) * 1992-08-17 1993-07-13 Cobile Alfredo P Shock absorber type compressor
US20040189172A1 (en) * 2003-03-26 2004-09-30 Zhaofu Hu Array of barriers for flat panel displays and method for making the array of barriers

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5840753Y2 (ja) * 1974-02-27 1983-09-13 マブチモ−タ− カブシキガイシヤ デンドウソウチ

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2874449A (en) * 1954-12-30 1959-02-24 Philips Corp Method of providing an electrically conductive network on a support of insulating material
US3474511A (en) * 1966-03-16 1969-10-28 Fernseh Gmbh Method of making image orthicon pickup tube with high storage capacity

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2874449A (en) * 1954-12-30 1959-02-24 Philips Corp Method of providing an electrically conductive network on a support of insulating material
US3474511A (en) * 1966-03-16 1969-10-28 Fernseh Gmbh Method of making image orthicon pickup tube with high storage capacity

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2700135A1 (de) * 1976-01-16 1977-07-28 Philips Nv Verfahren zur herstellung einer farbbildroehre, durch dieses verfahren hergestellte farbbildroehre und vorrichtung zum durchfuehren dieses verfahrens
US4164059A (en) * 1976-01-16 1979-08-14 U.S. Philips Corporation Method of manufacturing a color display tube and color display tube manufactured by said method
FR2387507A1 (xx) * 1977-04-15 1978-11-10 Philips Nv
EP0074738A2 (en) * 1981-09-10 1983-03-23 Kabushiki Kaisha Toshiba Method for making CRT shadow masks
EP0074738A3 (en) * 1981-09-10 1983-07-27 Kabushiki Kaisha Toshiba Method for making crt shadow masks
US4482334A (en) * 1981-09-10 1984-11-13 Tokyo Shibaura Denki Kabushiki Kaisha Method for making CRT shadow masks
DE3411964A1 (de) * 1983-03-31 1984-10-18 Rca Corp., New York, N.Y. Kathodenstrahlroehre mit fokussierender maske
US4514658A (en) * 1983-03-31 1985-04-30 Rca Corporation Mesh lens focus mask for a cathode-ray tube
US4621214A (en) * 1984-04-19 1986-11-04 Rca Corporation Color selection means having a charged insulator portion for a cathode-ray tube
US5226801A (en) * 1992-08-17 1993-07-13 Cobile Alfredo P Shock absorber type compressor
US20040189172A1 (en) * 2003-03-26 2004-09-30 Zhaofu Hu Array of barriers for flat panel displays and method for making the array of barriers
US7336025B2 (en) 2003-03-26 2008-02-26 Tsinghua University Array of barriers for flat panel displays and method for making the array of barriers

Also Published As

Publication number Publication date
NL7013126A (xx) 1971-03-09
JPS4819107B1 (xx) 1973-06-11

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