US3776630A - Electrostatic printing method and apparatus - Google Patents

Electrostatic printing method and apparatus Download PDF

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Publication number
US3776630A
US3776630A US00233547A US3776630DA US3776630A US 3776630 A US3776630 A US 3776630A US 00233547 A US00233547 A US 00233547A US 3776630D A US3776630D A US 3776630DA US 3776630 A US3776630 A US 3776630A
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United States
Prior art keywords
plate
liquid
developer
substrate
latent image
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Expired - Lifetime
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US00233547A
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English (en)
Inventor
G Ohno
E Inoue
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Ohno Res & Dev Lab
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Ohno Res & Dev Lab
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/101—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material
    • G03G15/102—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material for differentially wetting the recording material
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/10—Bases for charge-receiving or other layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/16—Developers not provided for in groups G03G9/06 - G03G9/135, e.g. solutions, aerosols
    • G03G9/18—Differentially wetting liquid developers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S101/00—Printing
    • Y10S101/37—Printing employing electrostatic force
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S118/00—Coating apparatus
    • Y10S118/04—Curtain coater
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S118/00—Coating apparatus
    • Y10S118/18—Wire and cord die

Definitions

  • FIG. 1 A first figure.
  • An object of this invention is to provide an electrostatic printing method and an apparatus used therein, wherein a positive image can be reproduced from both positive and negative originals by a liquid developing method without danger of fire, odor and poison.
  • the opposing electrode may be previously attached to the print paper or may be designed as a separate member from the paper to provide an electrode surface disposed to contact the back side of the paper and to apply a voltage thereto.
  • the surface of the photosensitive layer is liquidrepellent and hence, the contamination of the printed image thereby is minimized and the optimum print can be reproduced by adjusting the applied voltage.
  • a positive print can be made from both positive and negative originals by changing the polarity of the applied voltage.
  • the developer comprises water as the carrier and hence, the developer is not objectionable in odor, poisonous and does not present a fire hazard.
  • FIG. 1 shows the contact angle of a liquid drop on a liquid-repellent insulating film when the film is uncharged
  • FIG. 2 shows the same insulating film as shown in FIG. 1, except that the film is charged
  • FIG. 3 shows a cross-sectional view of a photosensitive plate according to this invention
  • FIGS. 9 and 10 show illustrative embodiments of the electrostatic printing apparatus according to this invention.
  • the developer is reduced and development is not sufficiently carried out. If the size of pores is less than 101.1,, they are often plugged up by impurities contained in the developer, and if the size is over 400p, a uniform image is not obtained. If the space between pores is less than 10 1. or more than 100p., the accuracy of image is not good.
  • Such finely porous substrate can be easily made by conventional methods of making a porous metal filter.
  • the developer taking the form of a mixture of photoconductive particles and a resin solution is applied to the porous substrate 3 by an electrostatic painting method (the substrate 3 having been used as an electrode) to a predetermined thickness so that a photoconductive layer is formed on the surface of the substrate 3.
  • a solution of the particles charged in a polarity opposite to that of the substrate are electrodeposited onto the substrate by spray coating.
  • an inorganic photosemiconductor such as amorphous selenium is used as photosensitive material, the layer can be easily formed by vacuum deposition under suitable voltages.
  • liquid-repellent resins such as polyethylene, polystyrene, alkyd resin, silicone varnish or 3- fluoroethylene chloride resin are used as a binder in the developer solution.
  • the photoconductive material is mixed with the binder (see Example 1, for a bindertype photoconductive layer).
  • a film of the above mentioned liquid-repellent resins may be formed on the photoconductive layer (see Example 2); this layer may be formed by vacuum deposition of an inorganic semiconductor.
  • a liquid-repellent photoconductive photosensitive plate having fine pores over the surface is obtained.
  • Other known photoconductive layers, if they are porous and liquid-repellent, may be used in this invention.
  • An electrode 17 which provides a contact surface to a paper to be printed, is arranged to oppose the plate 20 as shown.
  • a DC voltage is applied between the substrate 10 and the electrode 17 by a potential source 18, so as that the po larity of the substrate 10 is the same as that of the charge of the latent image 15 and the polarity of the opposing electrode 17 is opposite.
  • An electric field is formed between the plate 20 and the electrode 17; the resulting field is much stronger through the portion of the plate 20 where the latent image is present than in the part where the image does not exist. Accordingly, the liquid developer does not exude through the pores to the surface of those portions of the plate 20 where no latent image exists due to repulsing influence of the liquid-repellent layer.
  • the field where the latent image exists assumes a minimum value so that electrostatic polarization or induction of the liquid developer in the pores cannot occur and the field does not drive the liquid developer to the electrode 17.
  • the liquid iselectrostatically polarized or induced in the pores due to the electric field, and the contact angle is decreased so that the liquid developer is attracted to the electrode 17.
  • an inverse image of the electrostatic charge image is transferred and printed onto the paper 16.
  • the value of the electrostatic voltage for developing the electrostatic charge latent image according to this invention depends on the developing speed and on the kinds of the electrostatic latent image, the charge, the liquid-repellent layer and the developer.
  • FIGS. 7 and 8 show a unit for developing a latent image according to this invention. If a large amount of material remains on the photoconductive layer of the photosensitive plate, the influence of the exposure remains for a long time after exposure (i.e., pre-exposure fatigue). Under such conditions, electrostatic printing can be carried out due to the conductivity resulting from irradiation of light without electrostatic charge.
  • the liquid developer is supplied from the back side of the photosensitive plate 20, whose photoconductive layer 12 is formed on the surface of a finely porous conductive 10 substrate and contains trapping material, such as a low grade polymer including carboxylic acid or diphenyl picrye hydrazyle, and has a property of pre-exposure fatigue.
  • an electrostatic voltage is applied between the conductive substrate 10 of the photosensitive plate 20, and the electrode 17 which opposes the plate and provides a contact surface to apply a voltage from source 18 to the paper to be printed.
  • the field between the plate 20 and the opposing electrode is much more intensive where the plate has been irradiated than where the plate 17 has not be radiated, because the capacitance and conductivity of irradiated portions are increased thereby. Accordingly, the liquid developer does not exude through the pores to the surface of the plate due to inhibiting influence of the nonirradiated portion of the liquid-repellent layer.
  • the developer is electrostatically polarized or induced under the intensive field to be attracted to the opposing electrode, and exuded to the surface of the plate 20 because the contact angle of the developer with the p'ores surface is decreased.
  • the exuded developer may be contacted, absorbed and transferred to the paper 16 so that a reverse image can be obtained.
  • the liquid developer is supplied to the back side of the photosensitive plate 20 composed of a finely porous conductive substrate and a liquidrepellant photoconductive layer 12 formed on the substrate.
  • a transparent paper to be printed is placed on a transparent opposing electrode 17, which is disposed near and opposed to the photosensitive plate and has a transparent conductive layer 21 such as NESA layer (tin dioxide transparent conductive film).
  • the light image is irradiated onto the back side of the plate through the light image plate (negative or positive film) 22, and simultenously an electrostatic voltage is applied between the conductive substrate 10 of the photosensitive plate 20 and the transparent opposing electrode 17.
  • Developers used in this invention are liquid and include coloring agents, contact angle adjusting agents,
  • the coloring agent may be added to a solution, suspension or mixture of these aforementioned components.
  • hydrophilic dyes such as malachite green, methyl violet, victoria blue and persian orange are used.
  • alcohol soluble dyes such as pigment green and carmine F3 are used.
  • Contact angle adjusting agents are used for obtaining optimum contact angle in relation with the liquidrepellent property of the photoconductive photosensitive plate and the desired printing speed.
  • Suitable contact agents are prepared by mixing two liquids having different surface tensions or utilizing a small amount of surface activator.
  • the processed partof the plate is erased by a latent image erasing unit 35 and cleaned by a cleaning unit 36.
  • the latent image can be erased by a known method, for example, by irradiating the entire area of the surface of the latent image by light. Further, the developer still remaining on the plate after printing can be removed by a wet, soft brush roll, a felt roll or the like. Again a latent image is formed by the latent image forming unit 41 to be continuously printed.
  • Example 1 A photosensitive liquid was prepared of the following components:
  • Zink oxide g Bromophenol blue (1% solution) LScc Flueorescein (1% solution) 1.5cc Rose bengal (1% solution) l.Scc Styrene-buthadien copolymer 30g Toluene Brass particles (grain size 40p.) were press-sintered to form a 5 mm thick finely porous substrate.
  • the surface of the substrate was polished to serve as an electrode.
  • a photosensitive liquid is sprayed onto the polished surface by a nozzle.
  • a l KV voltage is applied between the nozzle and the substrate.
  • the photosensitive liquid is sprayed from the nozzle in the form of charged particles with a polarity opposite to that of the substrate.
  • the liquid is electrodeposited to 30p. thickness onto the plate, and after drying, silicone varnish was electrodeposited thereon to an average thickness in the order of p. in the same manner as the photosensitive liquid.
  • the resultant photoconductive photosensitive plate was given a negative electrostatic charge latent image by conventional means, such as 9 KV corona discharging unit.
  • a liquid .developer composed of the following components was suppliedv to the back side of the plate:
  • Example 2 The process was performed in the same manner as in Example 1, except that the plate was placed at a positive voltage, the opposing electrode being negative, and the voltage therebetween being 450V. A distinct negative image was obtained.
  • Example 3 A 100p. thick, brass plate was photoetched to produce fine pores having a diameter in the order of 40p. and a density of 225 pores per mm The photosensitive liquid of Example l'was sprayed and electrodeposited at lKV onto this conductive plate to provide a photosensitive layer with a thickness of 35uafter drymg. I
  • Carbon black 7g Victoria blue 0.15g Gelatin 2g Glycerol g Water 100cc A 280V electrostatic voltage was applied between the plate and the opposing electrode, the former being negative and the latter positive. A distinct blue-black positive image was obtained in correspondence with the original. When a 530V electrostatic voltage was applied in reverse polarity, the negative image was obtained.
  • Example 4 Charged, liquid particles of a photosensitive liquid composed of the following components were electrodeposited to the surface of a stainless steel mesh (250 mesh):
  • Zinc oxide 100g Bromophenol blue (1% solution) 2cc Rose bengal (1% solution) 2cc Diphenyl picryl hydrazyl 0.4g.
  • Styrene-buthadien copolymer 40g Toluene cc
  • the photosensitive liquid was sprayed by a nozzle under 3KV electrostatic voltage applied between the mesh and the nozzle. After drying a silicone varnish was coated on the photosensitive layer in the same manner as described in Example 2.
  • the resultant photosensitive plate was exposed to latent image in correspondence with the original, by a tungsten filament lamp. The plate was then moved to a paper placed on an opposing electrode.
  • Example 6 A liquid developer was prepared of the following components:
  • Zink oxide 50g Silicone varnish (resin 5%) 50g Rose bengal (2% methanol solution) 15cc Thinner lSOcc A 100p, thick copper plate was photo-etched to provide fine pores having a diameter in the order of 40p. and a density of pores per mm
  • the prepared photosensitive liquid developer was electrodeposited on the surface of this plate by a spary nozzle disposed at lKV. The thickness of the developer was 40p. after drying. Development and transfer was carried out at 600V, the photosensitive plate being positive and the opposing electrode negative. A distinct negative image was obtained in correspondence with the original.
  • said photoconductive layer comprises a first layer having a liquid repellent property and a second layer having a photoconductive property.
  • Apparatus as claimed in claim 1 wherein said photoconductive layer has a thickness in the range of 3; ⁇ . to 400p" 7. Apparatus as claimed in claim 1, wherein said openings have a diameter in the range of 10p. to p..

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Wet Developing In Electrophotography (AREA)
  • Liquid Developers In Electrophotography (AREA)
  • Printing Methods (AREA)
US00233547A 1971-03-29 1972-03-10 Electrostatic printing method and apparatus Expired - Lifetime US3776630A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1794071A JPS5528870B1 (enrdf_load_stackoverflow) 1971-03-29 1971-03-29

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878817A (en) * 1973-01-12 1975-04-22 Coulter Information Systems Apparatus for processing electrostatic images
US3898957A (en) * 1972-12-28 1975-08-12 Ricoh Kk Developing unit for electrostatic latent image
US3916827A (en) * 1973-03-07 1975-11-04 Scott Paper Co Perforate development electrode
US3941280A (en) * 1974-02-13 1976-03-02 Xerox Corporation Apparatus for controlling developer efficiency
US3973955A (en) * 1971-03-29 1976-08-10 Genji Ohno Electrostatic developing method
US3985437A (en) * 1973-01-12 1976-10-12 Coulter Information Systems, Inc. Electrostatic image recording device having partially collapsible toner applicator
US4210080A (en) * 1978-01-30 1980-07-01 Xerox Corporation Imaging method and apparatus
US4330193A (en) * 1979-10-01 1982-05-18 Xerox Corporation Development system
US4342823A (en) * 1973-03-07 1982-08-03 Scott Paper Company Perforate development electrode
US4384035A (en) * 1973-03-07 1983-05-17 Scott Paper Company Perforate development electrode
US4949129A (en) * 1989-07-03 1990-08-14 Eastman Kodak Company Apparatus for transferring toner images to a receiving sheet
US4982692A (en) * 1988-02-16 1991-01-08 Nec Corporation Apparatus for liquid development of electrostatic latent images
US5355794A (en) * 1990-08-17 1994-10-18 Herbert Freudenheim Process and apparatus for dry printing
US5495799A (en) * 1994-07-08 1996-03-05 Daniel; Jonathan R. Printing plate with a mesh layer forming pigment storing wells
US5815774A (en) * 1996-01-26 1998-09-29 Nec Corporation Image recording apparatus with photosensitive unit having porous insulating screen
US5943535A (en) * 1996-10-04 1999-08-24 Brother Kogyo Kabushiki Kaisha Device for developing a latent image with a water-based developing liquid
US6413689B1 (en) * 1999-08-31 2002-07-02 Nec Corporation Porous photosensitive body and method of manufacturing same
US11274997B2 (en) * 2013-02-05 2022-03-15 Tripath Imaging, Inc. Cytological staining compositions and uses thereof

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3220833A (en) * 1962-08-06 1965-11-30 Sun Chemical Corp Electrostatic printing method

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3220833A (en) * 1962-08-06 1965-11-30 Sun Chemical Corp Electrostatic printing method

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973955A (en) * 1971-03-29 1976-08-10 Genji Ohno Electrostatic developing method
US3898957A (en) * 1972-12-28 1975-08-12 Ricoh Kk Developing unit for electrostatic latent image
US3878817A (en) * 1973-01-12 1975-04-22 Coulter Information Systems Apparatus for processing electrostatic images
US3985437A (en) * 1973-01-12 1976-10-12 Coulter Information Systems, Inc. Electrostatic image recording device having partially collapsible toner applicator
US4342823A (en) * 1973-03-07 1982-08-03 Scott Paper Company Perforate development electrode
US3916827A (en) * 1973-03-07 1975-11-04 Scott Paper Co Perforate development electrode
US4384035A (en) * 1973-03-07 1983-05-17 Scott Paper Company Perforate development electrode
US3941280A (en) * 1974-02-13 1976-03-02 Xerox Corporation Apparatus for controlling developer efficiency
US4210080A (en) * 1978-01-30 1980-07-01 Xerox Corporation Imaging method and apparatus
US4330193A (en) * 1979-10-01 1982-05-18 Xerox Corporation Development system
US4982692A (en) * 1988-02-16 1991-01-08 Nec Corporation Apparatus for liquid development of electrostatic latent images
US4949129A (en) * 1989-07-03 1990-08-14 Eastman Kodak Company Apparatus for transferring toner images to a receiving sheet
US5355794A (en) * 1990-08-17 1994-10-18 Herbert Freudenheim Process and apparatus for dry printing
US5495799A (en) * 1994-07-08 1996-03-05 Daniel; Jonathan R. Printing plate with a mesh layer forming pigment storing wells
US5815774A (en) * 1996-01-26 1998-09-29 Nec Corporation Image recording apparatus with photosensitive unit having porous insulating screen
US5943535A (en) * 1996-10-04 1999-08-24 Brother Kogyo Kabushiki Kaisha Device for developing a latent image with a water-based developing liquid
US6413689B1 (en) * 1999-08-31 2002-07-02 Nec Corporation Porous photosensitive body and method of manufacturing same
US11274997B2 (en) * 2013-02-05 2022-03-15 Tripath Imaging, Inc. Cytological staining compositions and uses thereof

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JPS5528870B1 (enrdf_load_stackoverflow) 1980-07-30

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