US3856518A - Method of electrophotographically manufacturing a television screen using hygroscopic material - Google Patents

Method of electrophotographically manufacturing a television screen using hygroscopic material Download PDF

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Publication number
US3856518A
US3856518A US00335942A US33594273A US3856518A US 3856518 A US3856518 A US 3856518A US 00335942 A US00335942 A US 00335942A US 33594273 A US33594273 A US 33594273A US 3856518 A US3856518 A US 3856518A
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United States
Prior art keywords
phosphor
photoconductive layer
regions
layer
hygroscopic material
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Expired - Lifetime
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US00335942A
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English (en)
Inventor
F Strik
Soerland N Van
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US Philips Corp
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US Philips Corp
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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
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G8/00—Layers covering the final reproduction, e.g. for protecting, for writing thereon
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers

Definitions

  • ABSTRACT A method of electrophotographically manufacturing a display screen of a colour television display tube.
  • a light-absorbing layer is provided between the phosphor patterns.
  • the phosphor particles are previously provided with a layer of a hygroscopic material.
  • the hygroscopic material is wetted and hence made conductive between the provision of two phosphor patterns.
  • the hygroscopic material is dried and hence made non-conductive between the provision of the last phosphor pattern and the provision of the light-absorbing layer.
  • the invention relates to a method of electrophotographically manufacturing a display screen of a colour television display tube comprising the steps of: providing a conductive layer which can be fired on a face panel of the tube and providing a photoconductive layer which can be fired on the conductive layer; providing a first pattern of phosphor regions by uniformly electrically charging the photoconductive layer, forming a latent charge image which comprises charge in the regions corresponding to the said first pattern by exposing the photoconductive layer to light thrdugh a mask, and depositing phosphor particles charged with opposite polarity from an insulating developing liquid on the said charge image; providing in an analogous manner at least one subsequent pattern of phosphor regions; providing a light absorbing layer between the phosphor regions by uniformly electrically charging the photoconductive layer with the phosphor regions, uniformly exposing to light the
  • Such a method is known from the US. Pat. No. 3,475,l69.
  • This patent describes a few variations of the electrophotographic method.
  • a first variation which is termed direct imaging
  • the charged particles are deposited on the charged regions of the charge image because the charged particles have the opposite polarity of the charge image.
  • a second variation which is termed reverse imaging
  • the charged particles are deposited between the charged regions of the charge image because the charged particles have the same polarity as the charge image.
  • two exposure methods are possible.
  • a positive light pattern is formed of the apertures in a colour selection electrode.
  • a negative light pattern is formed of the apertures in a colour selection electrode, that is to say that each aperture in the colour selection electrode is reproduced by a shadow region on the photoconductive layer.
  • the phosphor regions on the display screen are smaller or narrower than the electron spots. This is of great importance since in that case a much smaller part of the surface of the display screen is occupied by phosphor regions and the intermediate space can be filled with a light-absorbing material. This has for its result that the colour television display tube can provide a much greater contrast because ambient light reflected by the screen is minimized.
  • the tolerance which is necessasry between the dimensions of the phosphor regions and the dimensions of the electron spots is produced in that the electron spots overlap the phosphor regions.
  • a colour television display tube of the shadow mask type in which the phosphor regions are smaller than the electron spots and are separated by regions having a light-absorbing material is known from the US. Pat. No. 3,l46,368.
  • This patent also describes a few methods of manufacturing such a tube. These methods come down to the fact that by carefully dosing the exposure to light, phosphor regions are manufactured on the screen which are smaller than the apertures in the colour selection electrode. This method is very difficult to perform in practice, while the achieved reduction farther is also not sufficient.
  • Another known method starts from a colour selection electrode having small provisional apertures. After using the colour selection electrode for the exposure, said apertures are made larger by after-etching or by removing a layer which was provided thereon temporarily. Of course this method is very cumbersome, which is a decisive drawback in practice.
  • Another object of the invention is to prevent pollution of previously provided patterns by the phosphor and/or the light-absorbing material of patterns provided afterwards. Another object of the invention is to provide a method of manufacturing a colour television display tube which is capable of displaying strongly saturated colours.
  • a method of the type described in the first paragraph is characterized in that, prior to mixing the phospor phosphor with the developing liquid, the phosphor particles for at least one of the patterns are provided with a layer of a hygroscopic material which is electrically conductive in the moist condition, that between the provision of two patterns of phosphor regions the hygroscopic material on the face panel is brought into a moist condition and that between the provision of the last pattern of phosphor regions and the provision of the light-absorbing layer the hygroscopic material on the face panel is brought into a dry condition.
  • the invention is based on investigations which have proved that the phosphor regions of already provided patterns have insufficient electrical conductivity to be discharged during the subsequent exposure which is necessary to provide a subsequent pattern. For that purpose it would be necessary for the phosphor parti cles to be made slightly conductive. The provision of a conductive layer on the phosphor particles as such, however, serves no purpose, for in that case the phosphor regions would also lose their charge during the last uniform exposure for providing the light-absorbing layer. So it must be possible for the conductive phosphor particles to be made non-conductive again. According to the invention, a hygroscopic material is used for that purpose which in itself is non-conductive but which is made conductive by the absorption of moisture and is afterwards made non-conductive by drying.
  • the drawing shows a face plate 1 of a colour television display tube of the shadow mask type.
  • An organic conductive layer 2 consisting of polyvinyl piperidinium chloride is provided on the face plate 1.
  • An organic photoconductive layer 3 consisting of polyvinyl carbazol is provided on the conductive layer 2.
  • a colour selection electrode 4 having apertures 5 is arranged immediately in front of the face plate I at exactly the same distance as afterwards in the operating tube.
  • a light source 6 of comparatively large dimensions throws light through the apertures 5.
  • a correction lens for accurate matching of the place of the light source to the deflection point of the electron beam in the operating tube is arranged between the light source 6 and the shadow mask 4.
  • the light spots 7 on the conductive layer 3 show a half-shadow 8.
  • the photoconductive layer 3 Prior to the exposure to light, the photoconductive layer 3 is provided with a negative surface charge. This is carried out by exposing the layer 3 to a corona discharge of an electrode which is at a high potential relative to the conductive layer 2. This is a known method which is also described in the U.S. Pat. No. 3,475,169. In the places illuminated by the light source the photoconductive layer 3 becomes conductive as a result of which the negative surface charge leaks away to the conductive layer 2.
  • the light source 6 is first arranged in the deflection point of the electron beam which in the operating tube is to impinge upon the discrete regions with green phosphor. The light source is then arranged in the deflection point for blue.
  • a suspension which comprises positively charged red luminescing phosphor particles in an insulating liquid is sprayed against the photoconductive layer.
  • the said liquid consists of branched hydrocarbons, for example. a mixture of octane and nonane.
  • a hygroscopic material for which, for example, a mixture of polyvinyl alcohol, choline chloride and glycerin is very suitable.
  • the red phosphor adheres to the oppositely charged unexposed places which form a pattern of dots having diameters smaller than the diameters of the apertures 5.
  • the display screen After drying the provided layer of red phosphor dots, the display screen is exposed to moist air for some time. As a result of this the hygroscopic material with which the phosphor grains are covered absorbs some water and the phosphor dots become conductive.
  • the photoconductive layer 3 with the conductive phosphor dots is then again provided with a negative surface charge and exposed to light for providing the next pattern of phosphor dots. Since the red phosphor dots are conductive, the surface charge thereof can leak away via the exposed parts of the photoconductive layer 3.
  • the next patterns of phosphor dots are provided in an entirely analogous manner.
  • the display screen provided with all the patterns of phosphor dots, usually red, blue and green, is then heated in dry air as a result of which the water is expelled from the hygroscopic material around the phosphor grains.
  • the photoconductive layer 3 is then provided with a positive surface charge. After uniform exposure of the photoconductive layer 3, said charge leaks away everywhere with the exception of the phosphor dots which are now non-conductive.
  • the space between the phosphor dots is then filled with a lightabsorbing material.
  • a suspension is sprayed against the photoconductive layer 3 which consists of positively charged particles of a black pigmentation agent, for example graphite or a black metal oxide, in an insulating liquid.
  • the light-absorbing material is repelled by the charge of the same sign of the phosphor dots and adheres to the remaining surface between the phosphor patterns.
  • the organic layers 2 and 3 are then removed by firing after which the phosphors and the light-absorbing substance immediately adhere to the glass of the display screen 1.
  • the invention is not only suitable for manufacturing a colour television display tube of the shadow mask type but that it may also be used in manufacturing other types of display tubes.
  • the problem of pollution of previously provided patterns with the phosphorof patterns provided afterwards actually always occurs in those cases where the direct imaging as stated in the U.S. Pat. No. 3,475,169 is used for providing the phosphor patterns and/or subsequently a light-absorbing layer between the phosphor patterns is provided with the reverse imaging.
  • a method of electrophotographically manufacturing a display screen of a color television display tube comprising a shadow mask and a face panel comprising the steps of:
  • said face panel comprising a fireable conductive layer disposed thereon and a fireable photoconductive layer disposed on said conductive layer;
  • first phosphor particles comprising an outer layer of a hygroscopic material which is electrically conductive in a moist condition
  • step (f) providing a light-absorbing layer between said phosphor regions by uniformly elecsaid photoconductive layer through a shadow 5 trostatically charging said photoconductive layer mask, thereby forming a latent charge image which with said phosphor regions, selectively discharging comprises charges in the regions corresponding to regions of said photoconductive layer and said dethe said first pattern and then depositing on the posited phosphor regions by uniformly exposing said charge image and from an insulating developsaid photoconductive layer with the said phosphor ing liquid, first phosphor particles charged with op- 10 regions. and depositing between the charged phosposite polarity to said latent charge image;

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US00335942A 1972-03-04 1973-02-26 Method of electrophotographically manufacturing a television screen using hygroscopic material Expired - Lifetime US3856518A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL7202907A NL7202907A (xx) 1972-03-04 1972-03-04

Publications (1)

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US3856518A true US3856518A (en) 1974-12-24

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US00335942A Expired - Lifetime US3856518A (en) 1972-03-04 1973-02-26 Method of electrophotographically manufacturing a television screen using hygroscopic material

Country Status (11)

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US (1) US3856518A (xx)
JP (1) JPS5138216B2 (xx)
AR (1) AR193568A1 (xx)
AU (1) AU5268873A (xx)
BE (1) BE796240A (xx)
CA (1) CA982388A (xx)
ES (1) ES412252A1 (xx)
FR (1) FR2174936B1 (xx)
GB (1) GB1358147A (xx)
IT (1) IT981034B (xx)
NL (1) NL7202907A (xx)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4095134A (en) * 1975-01-10 1978-06-13 U.S. Philips Corporation Electrophotographic preparation of color television display tube including rinsing phosphor pattern with solution of antistatic agent in apolar solvent
US4399090A (en) * 1979-10-18 1983-08-16 U.S. Philips Corporation Method of producing mouldings and layers of inorganic materials
US4921767A (en) * 1988-12-21 1990-05-01 Rca Licensing Corp. Method of electrophotographically manufacturing a luminescent screen assembly for a cathode-ray-tube
US4990416A (en) * 1989-06-19 1991-02-05 Coloray Display Corporation Deposition of cathodoluminescent materials by reversal toning

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5451323U (xx) * 1977-09-19 1979-04-09
JPS5934106Y2 (ja) * 1978-03-08 1984-09-21 東芝ライテック株式会社 巻線装置
JPS54155419A (en) * 1978-05-27 1979-12-07 Anzen Dengu Kk Temperature protector for coil
NL8102224A (nl) * 1981-05-07 1982-12-01 Philips Nv Werkwijze voor het langs elektrofotografische weg vervaardigen van een beeldscherm voor een kleurenbeeldbuis.
JPS58196816U (ja) * 1982-06-25 1983-12-27 セイコーエプソン株式会社 変圧器
JPH0787077B2 (ja) * 1988-04-13 1995-09-20 三菱電機株式会社 インライン型シャドウマスク式カラーブラウン管の露光装置

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3139340A (en) * 1962-01-17 1964-06-30 American Optical Corp Cathode ray tube face plates and method of making the same
US3365292A (en) * 1968-01-23 Rauland Corp Method of establishing a light absorbing design on a screen structure of an image reproducer
US3475169A (en) * 1965-08-20 1969-10-28 Zenith Radio Corp Process of electrostatically screening color cathode-ray tubes
US3489556A (en) * 1966-03-16 1970-01-13 Zenith Radio Corp Process fo electrostatically screening color cathode-ray tubes
US3489557A (en) * 1966-03-16 1970-01-13 Zenith Radio Corp Process of electrostatically screening a color cathode-ray tube
US3615459A (en) * 1968-11-06 1971-10-26 Zenith Radio Corp Method of screening a color image reproducer
US3615462A (en) * 1968-11-06 1971-10-26 Zenith Radio Corp Processing black-surround screens
US3632339A (en) * 1969-04-28 1972-01-04 Zenith Radio Corp Method of screening a color cathode-ray tube
US3745398A (en) * 1969-07-04 1973-07-10 Hitachi Ltd Cathode ray tube screen having contiguous,overlapping color areas

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3365292A (en) * 1968-01-23 Rauland Corp Method of establishing a light absorbing design on a screen structure of an image reproducer
US3139340A (en) * 1962-01-17 1964-06-30 American Optical Corp Cathode ray tube face plates and method of making the same
US3475169A (en) * 1965-08-20 1969-10-28 Zenith Radio Corp Process of electrostatically screening color cathode-ray tubes
US3489556A (en) * 1966-03-16 1970-01-13 Zenith Radio Corp Process fo electrostatically screening color cathode-ray tubes
US3489557A (en) * 1966-03-16 1970-01-13 Zenith Radio Corp Process of electrostatically screening a color cathode-ray tube
US3615459A (en) * 1968-11-06 1971-10-26 Zenith Radio Corp Method of screening a color image reproducer
US3615462A (en) * 1968-11-06 1971-10-26 Zenith Radio Corp Processing black-surround screens
US3632339A (en) * 1969-04-28 1972-01-04 Zenith Radio Corp Method of screening a color cathode-ray tube
US3745398A (en) * 1969-07-04 1973-07-10 Hitachi Ltd Cathode ray tube screen having contiguous,overlapping color areas

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4095134A (en) * 1975-01-10 1978-06-13 U.S. Philips Corporation Electrophotographic preparation of color television display tube including rinsing phosphor pattern with solution of antistatic agent in apolar solvent
US4399090A (en) * 1979-10-18 1983-08-16 U.S. Philips Corporation Method of producing mouldings and layers of inorganic materials
US4921767A (en) * 1988-12-21 1990-05-01 Rca Licensing Corp. Method of electrophotographically manufacturing a luminescent screen assembly for a cathode-ray-tube
US4990416A (en) * 1989-06-19 1991-02-05 Coloray Display Corporation Deposition of cathodoluminescent materials by reversal toning

Also Published As

Publication number Publication date
JPS5138216B2 (xx) 1976-10-20
BE796240A (fr) 1973-09-03
ES412252A1 (es) 1976-01-01
NL7202907A (xx) 1973-09-07
GB1358147A (en) 1974-06-26
IT981034B (it) 1974-10-10
JPS48102973A (xx) 1973-12-24
CA982388A (en) 1976-01-27
DE2308178A1 (de) 1973-09-13
FR2174936A1 (xx) 1973-10-19
DE2308178B2 (de) 1976-11-11
FR2174936B1 (xx) 1977-09-02
AR193568A1 (es) 1973-04-30
AU5268873A (en) 1974-08-29

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