US3775116A - Method for making a phosphor screen of a cathode-ray tube - Google Patents

Method for making a phosphor screen of a cathode-ray tube Download PDF

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Publication number
US3775116A
US3775116A US00204020A US3775116DA US3775116A US 3775116 A US3775116 A US 3775116A US 00204020 A US00204020 A US 00204020A US 3775116D A US3775116D A US 3775116DA US 3775116 A US3775116 A US 3775116A
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United States
Prior art keywords
light
photosensitive layer
shadow mask
layer
phosphor
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Expired - Lifetime
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US00204020A
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English (en)
Inventor
T Takemoto
Y Tomita
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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
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22—Applying luminescent coatings
    • H01J9/227—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines
    • H01J9/2271—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines by photographic processes

Definitions

  • ABSTRACT A layer through which light can pass subject to some attenuation is provided on that surface of a shadow mask which opposes to a phosphor screen within a cathode-ray tube, a photosensitive layer is provided on the first-mentioned layer, light-permeating apertures smaller than the light-permeating openings of the shadow mask are formed in the photosensitive layer, and phosphor dots are formed using the assembly thus obtained.
  • a recent shadow-mask type color cathode-ray tube has been improved in brightness and contrast with such a construction that phosphor dots smaller in diameter than openings of a shadow mask are formed on the inner surface of a faceplate, and that the interstice among the phosphor dots is filled up with a colored material which absorbs external light.
  • phosphor dots in this case is, for example, a method in which a film of the colored material absorbing external light is applied, apertures smaller in diameter than the openings of the shadow mask are formed at positions for forming the phosphor dots thereat, and 'the phosphor dots are formed in conformity with the pattern of the smaller apertures. More specifically, a photoresist film on the inner surface of the faceplate is exposed to light through a certain pattern ofmask holes to form photoresist dots smaller in diameter than the mask holes. Thereafter, the colored material is applied on that part of the inner surface of the faceplate which is not covered, and on the photoresist dots. The photoresist dots are then removed to obtain'a predetermined diameter of phosphor dots.
  • phosphor dots are first applied and formed on the inner surface of the faceplate, there-after the colored material is applied onto the entire inner surface of the faceplate including the phosphor dots, and exposure is carried out under this state'from the outer surface of the faceplate.
  • a variety of such methods have been heretofore proposed. 7
  • the shadow mask has a smaller diameter of openings than a predetermined one, and therefore requires post etching, namely, after completion of a predetermined exposure step, etching is carried out with such an etchant as a solution of ferric chloride to make the smaller diameter the predetermined one.
  • the faceplate of each cathode-ray tube has the phosphor dots formed in conformity with the corresponding shadow mask. Therefore, if a defective unit is caused at, for example, the post-etching, a faceplate whose phosphor dots are formed by the defective shadow mask becomes also defective. The economical advantages of the method are accordingly questionable.
  • this invention is characterized in that a shadow mask is covered .with a photosensitive layer and a lightpermeating and -attenuating layer to form a shadow mask assembly, and that a phosphor layer on the inner surface of a faceplate is exposed to light through the shadow mask assembly which, as will be hereinafter stated, has a desired phosphor-dot pattern of effective light-passing apertures of a diameter temporarily made smaller than that of openings of the shadow mask.
  • a method for making a phosphor screen of a cathode-ray tube comprising the steps of: providing a layer, through which light can pass subject to some attenuation, on
  • a shadow mask which opposes to said phosphor screen within said cathode-ray tube, said shadow mask being provided with a pattern of lightpermeating openings; providing a photosenstive layer on the light-permeating and -attenuating layer; exposshadow mask assembly; exposing a phosphor layer to light using said shadow mask assembly obtained; and forming a phosphor-dot pattern by a developing treatment.
  • the method for making a phosphor screen of the present invention offers such advantages that the di mensional accuracy of applied and formed phosphor, dots is high and the production cost is lowered, eliminating various problems attendant upon the partial prevention of corrosion of the shadow mask, maintenance of the diameter of the openings of the shadow mask, reetching of the shadow mask after an exposure opera tion, and so forth.
  • FIG. 1 is a sectional view of a part of a shadow mask assembly before it is exposed to light
  • FIG. 2 is a sectional view of a similar part of the shadow mask assembly shown in FIG. 1 but after it has been exposed to light.
  • a shadow mask 1 having a predetermined diameter of openings 10 is prepared.
  • a photosensitive sheet 2 consisting of a photosensitive layer 20 and a lightpermeating and -attenuating layer 2b (hereinbelow termed the transparent attenuation sheet) is stuck through a transparent binding layer 3 to that surface 1a of the shadow mask I which opposes to a phosphor screen, so closely that the photosensitive sheet 2 may not become crumpled.
  • the photosensitive layer 20 is closer to the phosphor screen than the transparent sheet 2b.
  • the close adherence may also be directly made without the binding layer 3 as mentioned above, by the use of the method of, e. g.,- thermocompression bonding or vacuum adherence.
  • the photosensitive layer 20 may be of a material, such as polyvinyl chloride, which has the property of causing the reaction of photopolymerization upon irradiating light thereon, being highly polymerized and losing tackiness.
  • a material which, as in polyvinyl carbazole, has the property of being changed in the charged state upon irradiation with light.
  • particles of a light-impermeable material 5 such as carbon and graphite and having a particle size of 20 60 millimicrons or so are uniformly sprinkled over the photosensitive layer 2a.
  • the powder on the light-exposed portions 4 is removed by a well-known method such as air blow and solvent immersion.
  • the exposed portions 4 becomes light-permeable
  • a covering layer of the light-impermeable material 5 is formed at the part other than the exposed portions 4, and the effective light-passing aperture smaller than the openings of the shadow mask 1 are provided in the photosensitive sheet 21.
  • the fixation of the layer of the light-impermeable material 5 may, if necessary, be made with a bonding agent, etc.
  • the photosensitive layer 2a is a tacky one as made of the aforesaid polyvinyl chloride
  • the light-exposed portions 4 lose tackiness by the exposure, and hence, the light-impermeable material 5 does not adhere to the portions. For this reason, the light-permeating portions are formed.
  • An example of the diameter of the effective light-passing apertures was attained by such method, as below.
  • the diameter of the openings 10 of the shadow mask was 0.32mm, the thickness of the transparent attenuation sheet 2b was 8,1, and the thickness of the photosensitive layer 2a was 1;!
  • the exposure was carried out with a mercury-arc lamp of 400W located at a position distant by approximately 30cm from the shadow mask 1 1. Thereafter, carbon powder of, e.g., mg. was sprinkled, and the air blow was performed. As a result, the diameter of the light-exposed portions 4 became approximately 0.23mm.
  • the photosensitive layer may contain a mixture consisting of a material such as the above-mentioned polyvinyl chloride and a light-impermeable material such as carbon, and the exposure portions 4 are deprived of tackiness by the exposure.
  • particles of the light-impermeable material are sprinkled on the photosensitive layer being tacky, both the particles and the layer are previously brought into the adhering state, and thereafter the light-impenneable material at the exposure portions 4 is removed by the exposure.
  • a faceplate for cathode-ray tubes which has phosphor dots smaller in diameter than the openings of the shadow mask 1. According to this method, the faceplate may be manufactured far more easily than in the prior-art post etching process previously stated.
  • the shadow mask assembly 11 is restored to the desired shadow mask 1 by removing the photosensitive sheet 2] after completion of the exposure.
  • the invention is easily applicable to, for example, a Chromatron (trade name) type color cathode-ray tube besides.
  • a method for making a phosphor screen of a cathode-ray tube comprising the steps of:
  • said photosensitive layer is a tacky photosensitive layer of polyvinyl chloride containing light-impermeable particles which looses tackiness by exposure to light whereby said light-impermeable particles may be removed therefrom during said development.
  • said photosensitive layer is a tacky photosensitive layer losing tackiness by exposure to light, and a lightimpermeable particle layer is provided on that part of said photosensitive layer at which the tackiness is not lost, after exposing said photosensitive layer to light.
  • the photosensitive layer is made of polyvinyl carbazole and the light-impermeable particle layer is formed of carbon particles.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
US00204020A 1970-12-04 1971-12-02 Method for making a phosphor screen of a cathode-ray tube Expired - Lifetime US3775116A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP10684570 1970-12-04

Publications (1)

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US3775116A true US3775116A (en) 1973-11-27

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US00204020A Expired - Lifetime US3775116A (en) 1970-12-04 1971-12-02 Method for making a phosphor screen of a cathode-ray tube

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US (1) US3775116A (enrdf_load_stackoverflow)
DE (1) DE2159626A1 (enrdf_load_stackoverflow)
FR (1) FR2117311A5 (enrdf_load_stackoverflow)
GB (1) GB1379047A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841876A (en) * 1972-06-30 1974-10-15 Hitachi Ltd Method for making a phosphor screen of a cathode-ray tube
US3931442A (en) * 1973-03-02 1976-01-06 Gte Sylvania Incorporated Temporary modification of a pattern mask for use in forming a color CRT screen and a process for modifying the same
US4567071A (en) * 1983-06-29 1986-01-28 Erich Glass Fast-heating cathode

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4223083A (en) * 1977-12-27 1980-09-16 Tektronix, Inc. Virtual mask exposure system for CRT screen manufacture

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2961314A (en) * 1955-06-24 1960-11-22 Zenith Radio Corp Method of manufacturing color image reproducer
US3070441A (en) * 1958-02-27 1962-12-25 Rca Corp Art of manufacturing cathode-ray tubes of the focus-mask variety
US3653901A (en) * 1969-10-31 1972-04-04 Rca Corp Color kinescope production with a temporary mask

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2961314A (en) * 1955-06-24 1960-11-22 Zenith Radio Corp Method of manufacturing color image reproducer
US3070441A (en) * 1958-02-27 1962-12-25 Rca Corp Art of manufacturing cathode-ray tubes of the focus-mask variety
US3653901A (en) * 1969-10-31 1972-04-04 Rca Corp Color kinescope production with a temporary mask

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841876A (en) * 1972-06-30 1974-10-15 Hitachi Ltd Method for making a phosphor screen of a cathode-ray tube
US3931442A (en) * 1973-03-02 1976-01-06 Gte Sylvania Incorporated Temporary modification of a pattern mask for use in forming a color CRT screen and a process for modifying the same
US4567071A (en) * 1983-06-29 1986-01-28 Erich Glass Fast-heating cathode

Also Published As

Publication number Publication date
FR2117311A5 (enrdf_load_stackoverflow) 1972-07-21
DE2159626A1 (de) 1972-06-22
GB1379047A (en) 1975-01-02

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