Classifications

• • 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
  • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
  • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
  • H01J29/18—Luminescent screens
  • H01J29/20—Luminescent screens characterised by the luminescent material
• • 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
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
  • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
  • C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
  • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
• • 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
  • H01J9/2276—Development of latent electrostatic images

Definitions

• the present invention relates to a method of manufacturing dry-powdered, double-coated phosphor particles with silica and titanic-coupling for use in
• a color CRT 10 generally comprises an evacuated glass envelope consisting of a panel 12, a funnel 13 sealed to the panel 12 and a tubular neck 14 connected by the funnel 13, an electron gun 11 centrally mounted within the neck 14 and a shadow mask 16
• a three color phosphor screen is formed on the inner surface of a display window or faceplate 18 of the panel 12.
• the electron gun 11 generates three electron beams 19a or 19b, said beams being directed along convergent paths through the shadow mask 16 to the screen 20 by means of several lenses of the gun and a high potential applied through an anode button 15 and being deflected by a deflection yoke 17 so as to scan over the screen 20 through apertures or slits 16a formed in the shadow mask 16.
• the phosphor screen 20 comprises an array of three phosphor elements R, G and B of three different emission colors arranged in a cyclic order of a predetermined structure of multiple-stripe or multiple-dot shape and a matrix of light-absorptive material surrounding the phosphor elements R, G and B.
• a thin film of aluminum 22 overlies the screen 20 in order to provide a means for applying the uniform potential to the screen 20, increase the brightness of the phosphor screen and prevent the burning of the phosphor screen due to ions that are produced as the result of a decomposition by collision of gases residing on the tube with the electron beams emitted from the electron gun and the decreasing of the potential of the phosphor screen.
• a film of resin such as lacquer(not shown) may be applied between the aluminum thin film 22 and the phosphor screen to enhance the flatness and reflectivity of the aluminum thin film 22.
• a slurry of a photosensitive binder and phosphor particles is coated on the inner surface of the faceplate. It does not meet the higher resolution demands and requires a lot of complicated processing steps and a lot of manufacturing equipments, thereby necessitating a high cost in manufacturing the phosphor screen. And also, it discharges a large quantity of effluent such as waste water, phosphor elements, 6th chrome sensitizer, etc., with the use of a large quantity of clean water.
• FIGs. 3A through 3E schematically show various steps in the above-described manufacturing method.
• FIG. 3A represents a coating step that forms an electrically conductive layer 132 is formed on the inner surface of the faceplate 18 and overlies an photoconductive layer 134 on the conductive layer 132.
• the conductive layer 132 can be formed by conventionally applying a volatilizable organic conductive material consisting of about 1 to 50 weight % of a polyelectrolyte commercially known as Catfloc-c, available from Calgon Co., Pittsburgh, Pa., to the inner surface of the faceplate 18 in an aqueous solution containing about 1 to 50 weight % of 10% poly vinyl alcohol and drying the solution. Said conductive layer 132 serving as an electrode for the overlying photoconductive layer 134.
• the photoconductive layer 134 is formed by conventionally applying to the conductive layer 132, a novel photoconductive solution containing ultraviolet-sensitive material and by drying it .
• the ultraviolet-sensitive material can consist of bis dimethyl phenyl diphenyl butatriene, and one of trinitro fluorenone(TNF) , ethylanthraquinone(EA ) and their mixture.
• the photoconductive solution is prepared by dissolving 0.01 to 10 % by weight of the ultraviolet-sensitive material and 1 to 30 % by weight of polystyrene as a polymeric binder in a suitable solvent such as toluene or xylene.
• FIG. 3B schematically illustrates a charging step, in which the photoconductive layer 134 is charged to a positive potential of less than 1 Kvolt, preferably above 700 volts by a corona discharger 3b.
• the charging step does not require a dark environment since the photoconductive layer 134 is sensitive to ultraviolet rays below about 450nm of wave length.
• FIG. 3C schematically shows an exposing step.
• the shadow mask 16 is inserted in the panel 12 and the positively charged photoconductive layer 134 is selectively exposed through an ultraviolet-transmissive lens system 140 and apertures or slits 16a of the shadow mask 16 to the ultraviolet rays from a ultraviolet lamp 138 with each predetermined incident angle with respect to each aperture or slit 16a.
• the charges of the exposed areas are discharged through the grounded conductive layer 132 and the charges of the unexposed areas remain in the photoconductive layer 134, thus establishing a latent charge image in a predetermined array structure .
• This exposing step also does not require a dark environment since the ultraviolet rays are used. Three exposures with three different incident angles of the three electron beams, respectively are required for forming a light-absorptive matrix.
• FIG. 3D diagrammatically illustrates the outline of a developing step, in which, after removing the shadow mask 16, suitably charged, dry-powdered particles such as particular color-emitting phosphor particles or light-absorptive material particles are sprayed by compressed air toward a photoconductive layer 134 through a venturi tube 146 and a nozzle 144b from a hopper 148 and attracted to one of the charged or unexposed areas.
• the discharged or exposed areas depend upon the polarity of the charged particles due to electrical attraction or repulsion, thus one of the two areas is developed in a predetermined array pattern.
• a discharge electrode 144a such as a corona discharger for charging dry-powdered particles to be sprayed in the nozzle 144b.
• the light-absorptive material particles for directly developing the unexposed or positively charged areas are negatively charged and the phosphor particles are positively charged for reversely developing the exposed or discharged areas.
• the charging of the dry-powdered particles may be executed by a triboelectrical charging method disclosed in U.S. Pat. No. 4,921,767 issued to Datta at al . on May 1, 1990 using surface-treated carrier beads .
• FIG. 3E schematically illustrates a fixing step using a vapor swelling method.
• the surface of the polymers-contained photoconductive layer 134 in which the particles are attracted in a predetermined array, is applied to solvent vapor such as acetone, methyl isobutyl ketone, etc.
• solvent vapor such as acetone, methyl isobutyl ketone, etc.
• polymers contained in the photoconductive layer 134 are dissolved and the dry-powdered particles deposited on the developed areas of the photoconductive layer 134 are fixed by an adhesive property of said dissolved polymers .
• the dry-powdered particles should flow from the hopper 148 through the venturi tube to the nozzle 144b and be sprayed at the nozzle 144b toward and over the whole surface of the photoconductive layer 134 by the compressed air, and should be sufficiently charged with a corona discharge electrode 144a in the developing step, excellent flow and charge characteristics are required on the surfaces of the dry-powdered particles.
• the dry-powdered phosphor particles are coated with a polymethyl methacrylate layer and an overlying polyacrylamide layer in order to provide charge characteristics, said coatings still do not meet a uniform and sufficient chargeability demand and a fluidity demand in the phosphor particles .
• dry-powdered, silica-and-titanic-coupling coated phosphor particles for use in manufacturing a screen assembly for CRT are dispersively coated with silica particles and titanic-coupling on the surface thereof to enhance the flow and charge characteristics of said phosphor particles .
• a method of manufacturing dry-powdered, silica-and-titanic-coupling coated phosphor particles having improved fluid and charge characteristics for use in manufacturing a CRT screen comprises the first silica-coating steps of: (a) first-dispersing silica particles in methanol; (b) slowly adding dry-powdered phosphor particles to said silica-dispersed methanol; (c) second-dispersing methanol in the silica-dispersed phosphor particles-adding methanol; (d) filtering said resultant methanol of the second-dispersing step; (e) drying the filtered resultant of the filtering step; and (f) sieving, through a screen, said dried resultant of the drying step, thereby obtaining dry-powdered, silica-coated phosphor particles; and the titanic-coupling-coating steps of: (g) first-dispersing titanic-coupling particles in organic solvent like a
• said first-dispersing steps and said second-dispersing steps be performed by ultrasonic waves; said filtering steps be performed by a glass frit filter; and said drying steps be performed below 100 degrees centigrade for about 3 to 5 hours .
• a method of electrophotographically manufacturing a luminescent screen on an interior surface of a faceplate panel for a CRT comprising the steps of: (a) first-coating said surface of the panel with a volatilizable conductive layer; (b) second-coating said conductive layer with a volatilizable photoconductive layer; (c) establishing a substantially uniform electrostatic charge over the whole area of the inner surface of said photoconductive layer; (d) exposing selected areas of said photoconductive layer to visual lights or ultraviolet rays through a shadow mask to discharge the charge from the selected areas of the inner of the photoconductive layer; (e) developing the discharged, exposed areas with charged first color-emitting phosphor particles with dispersed silica-and-titanic-coupling coating after removing the shadow mask; (f) repeating said steps (c) to (e) for charged second and third color-emitting phosphor particles with dispersed silica-and-titanic-coupling
• a CRT comprises a luminescent viewing screen and means for selectively exciting areas of said screen to luminescence, said screen comprising picture elements of color emitting phosphors with silicon and titanium dispersed and coated thereon.
• FIG. 1 is a plan view partially in axial section of a color cathode-ray tube.
• FIG. 2 is a section of a screen assembly of the tube shown in FIG.l.
• FIGs . 3A through 3E show a series of steps in electrophotographically manufacturing the screen assembly with dry-powdered, silica-and-titanic-coupling coated phosphor particles in accordance with the present inventio .
• FIG. 4A is an enlarged section of one phosphor particle according to an example of the present invention for electrophotographically manufacturing the screen
• FIG. 4B is an enlarged section of one phosphor particle constituting a completed phosphor screen assembly made using phosphor particles of FIG. 4A.
• a double-coated phosphor particle P with silica Cl and titanic-coupling C2 according to one embodiment of the present invention is schematically shown in FIG. 4A, and a phosphor particle P on which silicon Si and titanium Ti are remained after baking is schematically shown in FIG. 4B.
• a method of manufacturing dry-powdered, silica-coated phosphor particles according to one embodiment of the present invention is as follows .
• silica particles 1 gram is dispersed in one liter of methanol by conventional mixing method and preferably ultrasonic waves. Then, 1 kilogram of dry-powdered phosphor particles is slowly added into the silica-dispersed methanol .
• phosphor particles After said phosphor particles are added, 0.5 liter of methanol is secondly dispersed into the resultant phosphor particles-added, silica-dispersed methanol by the conventional mixing method and preferably by ultrasonic waves. And then, the desired phosphor particles are filtered from the resultant mixture through the conventional filter and preferably through the glass frit filter, dried at the temperature of 60 to 80 degrees centigrade for 2 to 3 hours and then sieved through a 400 mesh screen. The resultant dry-powdered phosphor particles have silica particles Cl dispersively coated on the phosphor particles .
• the desirably silica-coated, dry-powdered phosphor particles obtained by the above-described manufacturing method may be used in the developing step in the electrophotographic process of manufacturing a phosphor screen assembly as described in relation to FIGs . 3A to 3E, in case that, prior to said silica coating, phosphor particles are coated with a polymethyl methacrylate layer(PM) and an overlying polyacrylamide layer(PA) by a conventional method to provide the electrical charge characteristics on the phosphor particles .
• silica-coated phosphor particles Since the resultant dry-powdered, silica-coated phosphor particles have the excellent flow characteristics due to the slippery nature of the silica particles, the cohesion phenomena of the phosphor particles as described in the above as one problem of the electrophotographic process is almost removed. Accordingly, the phosphor particles do not easily adhere to each other and the wall of the hopper or the tube during the develop step.
• the volatilizable constituents of the screen including the conductive layer 132, the photoconductive layer 134, the polymethyl methacrylate layer PM, the polyacrylamide layer and the remaining solvents can be easily driven off even in the shortened heating time or on the lower temperature and the desirable array of the phosphor particles can be obtained since the silica is dispersed and coated on the surfaces of the phosphor particles.
• a titanic-coupling C2 is dispersed and coated on the resultant dry-powdered phosphor particles with silica Cl coated, instead of prior coating of the polymethyl methacrylate layer(PM) and the overlying polyacrylamide layer(PA) for providing the electrical charge characteristics on the phosphor particles.
• the titanic-coupling comprises hydrophobic property group and hydrophilic property group.
• the structural formula of the titanic-coupling is as follows for an example:
• titanic coupling is dispersed and coated on phosphor particles and joined with metal of metallic sulfur compound or acid sulfur compound of phosphor particles.
• Si0 2 of phosphor particle surface is combined instead of hydrophilic property group(C H-,0) .
• the phosphor particles with titanic-coupling coated are easily charged with positive electricity by C 17 H 35 ° hydrophobic property group as shown in FIG. 4A. But, the electrical chargeability is come down when titanic-coupling is above 1 % of weight.
• One embodiment of the titanic-coupling coating method on the resultant silica-coated phosphor particles is as follows .
• titanic-coupling 10 grams are dispersed in 1 liter of organic solvent like N-nucleic acid by conventional mixing method and preferably ultrasonic waves .
• the titanic-coupling is commercially known as KR TTS, KR 46B, KR 55, KR 41B, KR 38S, KR 138S, KR 238S, 338X, KR 12, KR44, KR 9SA, KR34S, ETC.
• a spray film of lacquer is applied to the screen and then an aluminum thin film is vapor-deposited onto the lacquer film, as is known in the art.
• the screen is baked at a high temperature, as is known in the art and then the volatilizable constituents of the screen including the conductive layer 132, the photoconductive layer 134, the hydrophobic group, the hydrophilic group, etc., are driven off, thus the colorless transparent silicon particles Si and titanium particles Ti dispersively remaining on the surfaces of the phosphor particles as shown in FIG. 4B.
• the resultant phosphor particles are •easily charged with positive electric charge on the surface of the phosphor particles by rubbing or discharge electrode, therefore the time of developing is shortened in the developing step, volatile constituents are easily removed in the baking step because silica and titanic-coupling are dispersed and coated on the surface of phosphor particles, and the manufactured screen structure has an even thickness .
• the present phosphor particles can be used for electrophotographically manufacturing the screen by the method as described in U.S. Pat. 4,921,767 and can also be used in the conventional wet process, and that the present process for obtaining the phosphor particles with the flow and charge characteristics can be modified within the scope of the present invention.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)

Applications Claiming Priority (2)

Publications (1)

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Citations (3)

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• 1996
  • 1996-11-13 KR KR1019960053648A patent/KR100288720B1/ko not_active IP Right Cessation
  • 1996-12-30 WO PCT/KR1996/000270 patent/WO1998021739A1/en active Application Filing

Patent Citations (3)

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