US3778623A - Charging method of electrophotographic materials - Google Patents

Charging method of electrophotographic materials Download PDF

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Publication number
US3778623A
US3778623A US00281927A US3778623DA US3778623A US 3778623 A US3778623 A US 3778623A US 00281927 A US00281927 A US 00281927A US 3778623D A US3778623D A US 3778623DA US 3778623 A US3778623 A US 3778623A
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US
United States
Prior art keywords
photoconductive
coating
corona discharge
corona
region
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00281927A
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English (en)
Inventor
M Sato
M Takimoto
I Takahashi
T Komaki
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Fujifilm Holdings Corp
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Fuji Photo Film Co Ltd
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Publication date
Application filed by Fuji Photo Film Co Ltd filed Critical Fuji Photo Film Co Ltd
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/02—Sensitising, i.e. laying-down a uniform charge
    • 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
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
    • Y10S430/102—Electrically charging radiation-conductive surface

Definitions

  • ABSTRACT A charging method for an electrophotographic material comprising a highly insulating support and a photoconductive insulating coating thereon, which comprises subjecting a first region of the photoconductive coating to a first corona discharge of one polarity while simultaneously irradiating with light, whereby said irradiation is absorbed by said photoconductive coating, and at the same time subjecting a second region of said photoconductive coating which is continuous to and radiation insulated from said first region, to a second corona discharge of the opposite polarity and causing a relative movement between said electrophotographic material and the corona discharge devices in such a manner that said electrophotographic material is subjected to said first corona with light irradiation and then is subjected to said second corona successively, is disclosed.
  • the present invention relates to a charging method of an electrophotographic material which comprises a photoconductive coating directly provided on a high insulating support.
  • An electrophotographic coating directly provided on an insulating support can be electrostatically charged with a high uniformity by a method in which the coating is subjected to simultaneous corona discharging of positive and negative polarities at adjacent regions whereby the current flow is aided by a uniform irradiation of light onto the first region of the coating where the first corona discharge is carried out.
  • the coating is ultimately charged in the polarity equal to that of the second corona discharge.
  • An electrophotographic material having a support with a comparatively high resistance such as paper may be charged by the so called double corona method.
  • this method of charging is not applicable for materials having highly insulating supports such as polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyamide, polyimide, polyvinyl chlorode, diand triacetyl cellulose, etc. Accordingly, a thin conductive intermediate layer is required which may be formed, for example, by the vacuum deposition of metal. In this case a photoconductive coating is formed on such a conductive layer and the coating is charged by the usual corona charging means whereby the conductive thin layer is grounded.
  • Electrophotographic materials which comprise a highly insulating support and a photoconductive coating directly provided thereon can be charged by a method described in British Pat. No. 971,281.
  • the photoconductive coating is irradiated from the support side with light which is strongly absorbed by the coating to make the bottom portion contiguous to the support temporarily conductive.
  • a corona discharge is carried out from the frontside of the material while the bottom portion of the coating remains conductive and is grounded.
  • This method has the limitation that the support material must be optically transparent and moreover it is accompanied with probability of incomplete grounding of the bottom portion of the coating.
  • a conductive tip must be brought into firm contact with the photoconductive surface for the purpose of grounding and it sometimes mechanically damages the coating.
  • An object of the present invention is to provide a charging method of an electrophotographic material comprising a highly insulating support and a photoconductive insulating coating directly provided thereon, overcoming the above-cited shortcomings.
  • the present method comprises, subjecting a first region of an electrophotographic coating to a first corona discharge of one polarity with a simultaneous irradiation of light, and at the same time subjecting a second region, which is continuous to and irradiation insulated or shielded, i.e., by a light shielding plate from the first region to a second corona discharge of the opposite polarity, and causing a relative movement between the electrophotographic sheet and the corona discharge devices in such a manner that the electrophotographic sheet will first accept the first corona with light irradiation and then the second corona, successively.
  • FIG. 1 is a schematic cross-sectional view of an apparatus to carry out and to disclose the principle of the present invention.
  • FIG. 2 is another embodiment for carrying out the invention.
  • FIG. 3 is still another example of a charging apparatus to carry out the invention.
  • an electrophotographic material 1 comprises a highly insulating support 11 and a photoconductive insulating coating 12 provided thereon.
  • the photoconductive insulating coating may comprise, for example, a vacuum deposited amorphous selenium layer, an organic photoconductor, homogeneous mixtures of photoconductive powders (zinc oxide, cadmium sulfide) and insulating resins, etc.
  • Suitable examples of the insulating resins include a copolymer of vinylchloride and vinyl acetate, a copolymer of styrene and butadiene, a copolymer of styrene and butyl methacrylate, polyalkyl methacrylates, polyalkyl acrylates, polyvinyl acetate, polyvinyl butyral, alkyd resins, silicone resins, epoxy resins, epoxy ester resins, as well as copolymers, terpolymers or quadripolymers of (l) a vinyl monomer having hydroxy groups capable of reacting with an isocyanate and (2) a monomer such as styrene, an alkyl methacrylate or an alkyl acrylate, cross-linked with polyisocyanates, and an alkyd or epoxy ester cross-linked with polyisocyanates.
  • Suitable examples of the insulating support include polyethylene terephthalate, triacetyl cellulose, diacetylcellulose, polyethylene, vinyl chloride and vinylidene chloride films and paper or metals laminated thereon with the above plastic films.
  • a charging device which comprises a main corona discharge electrode 3, a shield case 31 for 3, a light source 4, an auxiliary corona discharge electrode 5, a shield case 51 for 5 which also acts as a light reflector, and a light shielding plate 6 having a thickness of about 0.1 to 1 mm.
  • the plate may be made of conductive or insulating material.
  • a negative high potential is applied to the main corona electrode 3, and a positive high potential is applied to the auxiliary electrode 5, respectively whereby the photoconductive coating 12 is uniformly irradiated by light using the light source 4 which activates the photoconductive coating and does not coat too strong memory in it.
  • Electrons abundantly present in the exposed area A are repelled by the negatively charged corona ions generated from the electrode 3 and attracted to the positive corona ions impinging onto the region A and finally neutralized there.
  • an accumulation of positive charges results at the boundary region between the exposed and unexposed regions.
  • negative charges deposited on the surface of the unexposed region forms an electric double layer together with the accumulated positive charges.
  • the material When the electrophotographic material 1 is transported in the direction shown by the arrow, the material is uniformly charged in a negative polarity. This method is also suitable for those materials which exhibit a photoconductive memory effect by irradiation prior to charging.
  • FIG. 2 illustrated a schematic cross sectional view of a specific apparatus to carry out the present invention.
  • the light shielding plate employed in the device shown in FIG. 1 is replaced by a shield case for a corona electrode 5.
  • this case not only forms a part of a light reflector 51 but also it forms a part of the shield case 31 for a main corona electrode 3.
  • a roll of an electrophotographic material is fed continuously into the apparatus to be charged.
  • Example 1 A photoconductive selenium coating of about micron thickness was vacuum deposited on a 150 micron thick polyethylene terephthalate film which had been irradiated with ultra-violet light to improve the surface adhesive properties.
  • the electrophotographic material thus prepared was subjected to charging with an apparatus as shown in FIG. 3.
  • the material 1 was placed on a non-plasticized polyvinyl chloride plate 7 of 10 mm in thickness.
  • a light shielding plate 6 was placed perpendicular to the material surface with one mm clearance between the lower end of the plate and the surface.
  • the plate was made of metal with 0.5 mm thickness and electrically isolated from the surroundings. Separated by the plate 6, two needle-shaped electrode 3 and 5, perpendicular to the surface to the material 1 were provided. The distance from the plate 6 to each needle was 50 mm.
  • the electrode 3 was kept at +8 KV, while 5 was kept at 8 RV.
  • a 100 W incandescent lamp 4 was provided near the electrode 5, and at a distance of 300 mm to the surface to be charged. When the lamp was put on, the polyvinyl chloride plate 7 bearing the material 1 was transported at a rate of l cm/sec in the direction shown by the arrow. The material 1 showed a surface potential of 250 volts immediately after being passed under the main corona electrode 3.
  • a 150 mm micron thick polyethylene terephthalate film was coated a mixture comprising 100 parts by weight of a photoconductive zinc oxide, trade name Sazex No. 2000," 14 parts by weight of a resin binder, a styrenated alkyd resin produced by Japan Reichhold Chemical Co., under the trade name Styresol No. 4400, 7 parts by weight of polyisocyanate compound as a curing agent for the alkyd resin, produced by Bayer A.G. under the trade name Desmodur L to give a dried coating thickness of about 7 microns.
  • the coated film was kept at 40 C for 16 hours to complete the curing.
  • a charging apparatus having the same arrangement and structure as described in Example 1 was employed to charge the film thus prepared.
  • the light shielding plate 6 was made of a 1 mm thick black nonplasticized polyvinyl chloride board.
  • the clearance between the end of the board and the film surface was about 1' mm, the distance from the incandescent lamp to the film surface was 200 mm, and the polarities of the electric potential applied to the two electrodes were reversed, i.e., -8 KV to the main corona electrode 3, and +8 KV to the auxiliary one 5.
  • the film was kept stationary under the arrangement for about 5 seconds, when a surface potential -l40 volts was observed in about a 2 mm width narrow band along the lower end of the light-shielding board 6. When the film was transported in the direction shown by the arrow, a wide area of the photoconductive surface could be uniformly charged.
  • irradiation of the photoconductive insulating layer is required to be carried out in a manner in which the layer is temporarily made conductive. It is not desirable to cause too strong a memory effect for photoconductivity in the layer, because it results in a reduction in the ultimate surface potential of the layer such a consideration of strong memory must be given when the photoconductive layer in which photoconductive powder is dispersed in resin is used. From this point of view, it is desirable to use a filter which absorbs a particular spectral range of light which causes an intensive memory effect. For instance, an ultra-violet light absorbing filter is preferably employed when a zinc oxide layer is used. Together with the filter, the light sources must be taken into account. When zinc oxide is dispersed in the resin, satisfactory results can be obtained by cutting the wavelength shorter than 390 mu.
  • a method for charging an electrophotographic material consisting of a highly insulating support for a photoconductive insulating coating having majority carriers of a predetermined polarity which comprises providing a first corona discharge device of a first polarity opposite to said predetermined polarity and a light source, providing a second corona discharge device of a polarity opposite to said first polarity, said first and second corona discharge devices being the only discharge devices, real or imaginary, provided, providing a shielding member between said light source and said second corona discharge, subjecting a first region of the photoconductive coating to said first corona discharge device while simultaneously irradiating with light from said light source whereby said irradiation is absorbed by said photoconductive coating, and at the same time subjecting a second region of said photoconductive coating which is immediately adjacent and continuous to said first region and radiation insulated therefrom by said shielding member to said second corona discharge device and causing a relative movement between said electrophotographic material and the cosisting of an amorph

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Photoreceptors In Electrophotography (AREA)
US00281927A 1971-08-20 1972-08-18 Charging method of electrophotographic materials Expired - Lifetime US3778623A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46063430A JPS4829441A (fr) 1971-08-20 1971-08-20

Publications (1)

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US3778623A true US3778623A (en) 1973-12-11

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US00281927A Expired - Lifetime US3778623A (en) 1971-08-20 1972-08-18 Charging method of electrophotographic materials

Country Status (5)

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US (1) US3778623A (fr)
JP (1) JPS4829441A (fr)
DE (1) DE2240776A1 (fr)
FR (1) FR2151293A5 (fr)
GB (1) GB1388434A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3886416A (en) * 1973-12-07 1975-05-27 Xerox Corp Method and apparatus for adjusting corotron currents
US4034221A (en) * 1975-04-07 1977-07-05 Ricoh Co., Ltd. Charging device for automatic copying apparatus
US4408865A (en) * 1981-11-23 1983-10-11 Hewlett Packard Company Corona discharge device for electrophotographic charging and potential leveling
US4413897A (en) * 1979-10-31 1983-11-08 Tokyo Shibaura Denki Kabushiki Kaisha Electrostatic copying apparatus
US9500978B2 (en) * 2014-07-25 2016-11-22 Ricoh Company, Ltd. Image forming apparatus including electric charge removing device and method of forming image

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5825661A (ja) * 1981-08-07 1983-02-15 Ricoh Co Ltd 帯電装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955938A (en) * 1955-08-01 1960-10-11 Haloid Xerox Inc Xerography
US3676117A (en) * 1967-10-20 1972-07-11 Katsuragawa Denki Kk Method of electrophotography

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2955938A (en) * 1955-08-01 1960-10-11 Haloid Xerox Inc Xerography
US3676117A (en) * 1967-10-20 1972-07-11 Katsuragawa Denki Kk Method of electrophotography

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3886416A (en) * 1973-12-07 1975-05-27 Xerox Corp Method and apparatus for adjusting corotron currents
US4034221A (en) * 1975-04-07 1977-07-05 Ricoh Co., Ltd. Charging device for automatic copying apparatus
US4413897A (en) * 1979-10-31 1983-11-08 Tokyo Shibaura Denki Kabushiki Kaisha Electrostatic copying apparatus
US4408865A (en) * 1981-11-23 1983-10-11 Hewlett Packard Company Corona discharge device for electrophotographic charging and potential leveling
US9500978B2 (en) * 2014-07-25 2016-11-22 Ricoh Company, Ltd. Image forming apparatus including electric charge removing device and method of forming image

Also Published As

Publication number Publication date
JPS4829441A (fr) 1973-04-19
FR2151293A5 (fr) 1973-04-13
GB1388434A (en) 1975-03-26
DE2240776A1 (de) 1973-03-01

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