US3753711A - Method for producing phosphor screen - Google Patents

Method for producing phosphor screen Download PDF

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Publication number
US3753711A
US3753711A US00207180A US3753711DA US3753711A US 3753711 A US3753711 A US 3753711A US 00207180 A US00207180 A US 00207180A US 3753711D A US3753711D A US 3753711DA US 3753711 A US3753711 A US 3753711A
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United States
Prior art keywords
phosphor
film
dotty
color
emission
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Expired - Lifetime
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US00207180A
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English (en)
Inventor
Y Kobayashi
K Yakeno
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Panasonic Holdings Corp
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Matsushita Electronics Corp
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Publication date
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Publication of US3753711A publication Critical patent/US3753711A/en
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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 phosphor screen for color picture tube is usually produced by the first step which comprises suspending a blue emission phosphor in an aqueous solution of photo-setting photosensitive material comprising polyvinyl alcohol and ammonium dichromate, applying thus obtained suspension to inner surface of face panel to form a photosensitive film, exposing said film through apertures of shadow mask and developing the exposed film to form dotty phosphor film and the sec- 0nd and the third steps of forming the dotty phosphor films of green and red emissions in this order by substantially the same procedure as that of the first step.
  • the dotty phosphor films formed at said first and second steps are treated with chromic acid solution to harden said films, whereby color mixing, namely, so-called color fogging caused by a phosphor of other color emission used at the subsequent step is reduced and color purity of emission from phosphor screen face is improved.
  • the present invention relates to a method for producing a phosphor screen which comprises forming multi-color emission phosphor dots on the inner surface of a face panel by photo-mechanical process utilizing photo-setting type photosensitive film.
  • phosphor screen in color picture tube is produced by the steps which comprise mixing polyvinyl alcohol and a dichromate such as ammonium dichromate as a photosensitizer in a predetermined ratio, dispersing a phosphor in said mixed liquid, uniformly applying the resultant suspension to the inner surface of the face panel, drying the applied suspension to form a photosensitive film, exposing said film in dotty form through apertures of a shadow mask and then developing the exposed film.
  • regular arrangement of dots of the tri-color emission phosphors is attained by respectively transferring the position of light source for exposure to the deflection center of electron beam for excitation of each phosphor and repeating the above mentioned each step using green, blue and red emission phosphors.
  • phosphor of different color emission necessarily adheres to the phosphor dots obtained at the first and the second steps except the phosphor dots obtained at the last step and it is difficult to make the adhesion amount of the different color phosphor zero. That is, according to the usual method for forming phosphor dots, it is impossible to completely remove, at the second and the third developing steps, the phosphor of different color emission which adheres to the surface of phosphor dots formed at the preceding step. if development for a long period is carried out to completely remove the adhered phosphor, even the phosphor dots adhering inner surface of face panel at the preceding step are also removed, namely, falling of dots is caused.
  • the object of the present invention is to provide an effective means for preventing color-mixing of each phosphor to obtain color picture tube having excellent images.
  • FIGS. 1, 2 and 3 are graphs which show relations between Cro concentration and colorfogging rate, between CrO, concentration and luminance and between Cr0, concentration and practicality, respectively.
  • said dotty film was subjected to dipping treatment with chromic acid solution of a predetermined concentration for several ten seconds and then thus treated film while in wet state was again washed with warm water.
  • FIG. 1 shows relation between concentration of chromic acid (Cr0,) in said treating solution and color fogging as a relative value taking as the amount of blue phosphor incorporated into green phosphor dots when no treatment with chromic acid solution was given.
  • FIG. 2 shows the relation between Cr0 concentration in the treating solution and luminance measured after baking at 500C for one hour on a green emission phosphor, namely, copper aluminum activated zinc sulfide cadmium sulfide phosphor [(Zn, Cd)S Cu, Al] used in the present invention. The result indicates that Cr0 concentration exceeding 10 percent is not preferred.
  • FIG. 3 shows a practical curve of Cr0 concentration in the treating solution obtained considering decrease of color fogging caused by film hardening treatment and allowable lower limit of luminance of the phosphor. That is, practical Cr0,-, concentration is up to 10 percent, preferably 0.5-10 percent, within which film hardening and allowable decrease of luminance are balanced. The peak of practical value is seen at a CrO concentration of about 5 percent.
  • the treatment with chromic acid solution is applied to the step of forming dots of the second phosphor, e.g., blue emission phosphor, whereby hardening of dotty film 'containing blue emission phosphor can be accelerated.
  • the phosphor screen of the usual color picture tube have tricolor phosphors, there is no necessity to apply said treatment with chromic acid solution to the step of forming phosphor dots of the third phosphor, e.g., red emission phosphor.
  • the treatment with chromic acid solution has the same film hardening effect even if the order of forming the dots of the first, the second and the third phosphors is changed.
  • such phosphor as exhibiting greater decrease of luminance duento adhesion of chromium should be employed later.
  • dots of red emission phosphor of a rare earth oxide are lastly formed, decrease of luminance due to adhesion of chromium is prevented to obtain bright phosphor surface.
  • the method of the present invention is characterized by the steps of applying a suspension of a given phosphor and a photo-setting type photosensitive material comprising polyvinyl alcohol and a dichromate to an inner surface of a face panel to form a photosensitive film, exposing and developing said film in dotty form to obtain a dotty film containing the given phosphor and subjecting the resultant dotty film to dipping treatment with chromic acid solution to harden the film.
  • the method of the present invention may also be employed when a phosphor screen is formed by the abovementioned steps of dots formation on a face panel having holes at the position on one surface at which dots of tricolor emission phosphors are to be formed and light absorbing film such as graphite on the other surface.
  • the present invention may be applied to production of color picture tube having a phosphor screen of stripe form, when polyvinyl alcoholdichromate system is used as the photosensitive film.
  • a method for producing a phosphor screen which comprises the steps of applying a suspension of a photo-setting type photosensitive material comprising polyvinyl alcohol and a dichromate and a phosphor to a surface of a screen forming plate to form a photosensitive film, exposing to actinic radiation and developing said film in a repetition pattern such as dotted form or stripe form to form phosphor film of the certain repetition pattern, and contacting said phosphor film with an aqueous solution of chromic acid having a pH of not more than 2.0 to harden the film.
  • said chromic acid solution is an aqueous solution containing an optional amount of up to 10 percent by weight of chromic acid.
  • a method for producing a phosphor screen of color picture tube which comprises the steps of applying a suspension of a phosphor and a photo-setting type photosensitive material comprising a polyvinyl alcohol and a dichromate to an inner surface of face panel of a cathode-ray tube to form a photosensitive film, exposing to actinic radiation and developing said film in dotty form to obtain dotty phosphor film and then allowing said film to contact with a chromic acid aqueous solution containing 0.5-10 percent by weight of chromic and having a pH of not more than 2.0 acid to harden the film.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US00207180A 1970-12-18 1971-12-13 Method for producing phosphor screen Expired - Lifetime US3753711A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45116099A JPS4935013B1 (enrdf_load_stackoverflow) 1970-12-18 1970-12-18

Publications (1)

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US3753711A true US3753711A (en) 1973-08-21

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US00207180A Expired - Lifetime US3753711A (en) 1970-12-18 1971-12-13 Method for producing phosphor screen

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US (1) US3753711A (enrdf_load_stackoverflow)
JP (1) JPS4935013B1 (enrdf_load_stackoverflow)
CA (1) CA954364A (enrdf_load_stackoverflow)
FR (1) FR2118808A5 (enrdf_load_stackoverflow)
GB (1) GB1340589A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4263384A (en) * 1978-09-29 1981-04-21 Hitachi, Ltd. Method of forming fluorescent screens of color picture tubes

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6414679U (enrdf_load_stackoverflow) * 1987-07-16 1989-01-25

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1763533A (en) * 1923-11-27 1930-06-10 Agfa Ansco Corp Process for hardening colloids
US2766098A (en) * 1952-11-19 1956-10-09 Diamond Alkali Co Method of obtaining a chromiumcontaining tanning substance
US3428454A (en) * 1965-05-03 1969-02-18 Philco Ford Corp Process for depositing particulate solid material on selected portions of a substrate

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1763533A (en) * 1923-11-27 1930-06-10 Agfa Ansco Corp Process for hardening colloids
US2766098A (en) * 1952-11-19 1956-10-09 Diamond Alkali Co Method of obtaining a chromiumcontaining tanning substance
US3428454A (en) * 1965-05-03 1969-02-18 Philco Ford Corp Process for depositing particulate solid material on selected portions of a substrate

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4263384A (en) * 1978-09-29 1981-04-21 Hitachi, Ltd. Method of forming fluorescent screens of color picture tubes

Also Published As

Publication number Publication date
GB1340589A (en) 1973-12-12
DE2162886A1 (de) 1972-06-29
FR2118808A5 (enrdf_load_stackoverflow) 1972-07-28
DE2162886B2 (enrdf_load_stackoverflow) 1975-04-03
JPS4935013B1 (enrdf_load_stackoverflow) 1974-09-19
AU3698271A (en) 1973-06-21
CA954364A (en) 1974-09-10

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