US3860857A - Electrophotographic transfer method - Google Patents

Electrophotographic transfer method Download PDF

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Publication number
US3860857A
US3860857A US288268A US28826872A US3860857A US 3860857 A US3860857 A US 3860857A US 288268 A US288268 A US 288268A US 28826872 A US28826872 A US 28826872A US 3860857 A US3860857 A US 3860857A
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US
United States
Prior art keywords
voltage
transfer
corona discharge
transfer sheet
transfer member
Prior art date
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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US288268A
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English (en)
Inventor
Ryoichi Namiki
Haruyoshi Kawano
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Ricoh Co Ltd
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Ricoh Co Ltd
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Publication date
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
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Publication of US3860857A publication Critical patent/US3860857A/en
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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
    • G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
    • G03G15/163—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using the force produced by an electrostatic transfer field formed between the second base and the electrographic recording member, e.g. transfer through an air gap
    • G03G15/1635—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using the force produced by an electrostatic transfer field formed between the second base and the electrographic recording member, e.g. transfer through an air gap the field being produced by laying down an electrostatic charge behind the base or the recording member, e.g. by a corona device

Definitions

  • ABSTRACT A method and means for efficiently transferring a toner image from a transfer member to a transfer sheet by means of a corona discharge wherein an alternating voltage biased with a DC voltage is used to produce the corona discharge to simultaneously neutralize an electrostatic force which is set up between the transfer member and the transfer sheet, thus making it easier to separate the transfer sheet from the transfer member.
  • the voltage is supplied to the corona discharge means by a transformer whose primary winding is connected to an AC source and whose secondary winding is connected to an AC source and the corona discharge means.
  • An oscillator may also be connected to the primary winding of the transformer to improve the DC wave form.
  • the present invention relates to electrophotographic image transfer and more particularly to a method and means for improving the separation of the transfer sheet from the transfer drum after toner transfer.
  • the corona discharge used in such a transfer was usually effected by applying a high DC voltage to a wire or a needle-like electrode in order to generate an uniform voltage whose polarity depends on the charged polarities of the toners and the layer of photoconductive material.
  • the invention provides an electrostatic transfer method wherein an efficient transfer is effected by applying an alternating voltage biased with a DC voltage for neutralizing the electrostatic force which is the cause of the attraction between the transfer member and the transfer sheet to make it easy to separate the two.
  • FIG. 1 is a diagrammatic cross sectional view of a transfer device in which the present invention is incorporated.
  • FIG. 2 illustrates an example of a waveform of the biased AC voltage.
  • FIG. 3 is a cross sectional view as in FIG. 1 of an embodiment using a wave form shaping oscillator in the corna discharge input circuit.
  • a transfer member 2 consisting of a drum (in the figure, shown with a portion broken away) having a layer of photoconductive material 1 on its outer surface is supported by a grounded shaft 3 so as to rotate in the direction of arrow a.
  • the layer of photoconductive material 1 may be of a material whose charging polarity is positive such as selenium or selenium sulfide.
  • the layer of photoconductive material may be made of one of such materials as cadmium sulfide, zinc oxide, poly-N-vinylcarbazole and the like.
  • a sheet provided with those layers may be mounted over the surface of the drum instead of mounting those layers directly upon the drum. Further, this layer of photoconductive material may be, for instance, on an electrostatic recording sheet.
  • the transfer member 2 is applied with a charge layer upon the surface of the layer of photoconductive material 1 at a position not shown in the figure during the rotation in the direction of arrow a and then exposed to light through a copy image to form an electrostatic latent image.
  • the latent image is then developed as a toner image and the layer of photoconductive material 1 is brought into a transfer position A shown in the Figure.
  • a charging device 7 consisting of a wire electrode 5 stretched within a frame 6 is positioned facing transfer member 2 and on each side of this charging device 7, transfer rollers 8 and 9 are mounted in pressure contact with the transfer member 2.
  • the electrode 5 may also be a needle-like electrode.
  • the wire electrode 5 is connected to the secondary winding of transformer T and the primary winding of the transformer is connected to an alternating current source.
  • the secondary winding of the transformer is connected to a positive pole of a DC source 10 whose negative pole is grounded.
  • the wire electrode 5 is supplied with an AC voltage E whose effective voltage is substantially the same as the corona starting voltage and a DC voltage whose magnitude is substantially one half of the AC effective voltage.
  • the resultant wave form is biased to the positive side as, for instance, shown in FIG. 2.
  • the transfer sheet 11 is fed between transfer member 2 and transfer roller 8 in synchronism with the rotation of transfer member 2 and pressed by both rollers 8 and 9 so as to come into pressure contact with transfer member 2.
  • Sheet 11 is applied with a corona discharge from the rear side through wire electrode 5 and proceeds in the direction of arrow b.
  • a corona discharge of reverse polarity with that of the image forming toners is started to effect an efficient transfer.
  • a corona discharge is started between transfer member 2 and transfer sheet 11 to such a degree as to neutralize the electrostatic force induced between transfer member 2 and transfer sheet 11 during the positive cycle portion.
  • the toners which were attracted to transfer sheet 11 through the corona discharge during the positive cycle portion Sa will not be repelled but rather either the charge upon the transfer member 2, overcharged through the corona discharge during the positive cycle portion Sa, or the residual charge at the time of forming the toner image, will be neutralized whereby the subsequent separation of transfer sheet 11 from the transfer member 2 may be effected easily without the need for any additional separating force or means.
  • the magnitude of applied voltage Sa and Sb may be controlled through the selection of the capacities of the transformer T and the DC source 10. So that if these are made variable the voltage may be adjusted thereby. It is mainly determined by the charging characteristics of toners which of Sa and Sb is made larger or whether the polarity of the DC bias voltage is made positive or negative. However, the absolute value of the DC bias voltage is preferably slightly less than one half of the effective value of the AC voltage and is preferably larger than 500 volts.
  • an electrophotographic device of the type comprising:
  • charging means at said transfer station for creating a corona discharge adjacent the opposite surface of said transfer sheet when brought into contact with said photoconductive surface to facilitate the transfer of said toner image thereto;
  • a device as in claim 1 wherein the effective value of said AC voltage is substantially that of the corona discharge starting voltage and the effective value of said DC voltage is approximately half of that of said AC voltage.
  • said voltage supplying means comprises a transformer whose primary winding is connected to an AC source and whose secondary winding is connected to said charging means and a DC source.
  • a device as in claim 3 further comprising an oscillator connected to said primary winding.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Color Electrophotography (AREA)
US288268A 1971-09-20 1972-09-12 Electrophotographic transfer method Expired - Lifetime US3860857A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7313671A JPS5441904B2 (enrdf_load_stackoverflow) 1971-09-20 1971-09-20

Publications (1)

Publication Number Publication Date
US3860857A true US3860857A (en) 1975-01-14

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Family Applications (1)

Application Number Title Priority Date Filing Date
US288268A Expired - Lifetime US3860857A (en) 1971-09-20 1972-09-12 Electrophotographic transfer method

Country Status (4)

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US (1) US3860857A (enrdf_load_stackoverflow)
JP (1) JPS5441904B2 (enrdf_load_stackoverflow)
DE (1) DE2245848A1 (enrdf_load_stackoverflow)
GB (1) GB1370976A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921042A (en) * 1974-11-25 1975-11-18 Xerox Corp Electrostatic reproduction machine with improved corona generating device
FR2320586A1 (fr) * 1975-08-06 1977-03-04 Xerox Corp Dispositif de transfert d'image pour xerographie
US4081212A (en) * 1974-11-18 1978-03-28 Oce-Van Der Grinten, N.V. System for electrostatically transferring powder images
US4105320A (en) * 1977-01-05 1978-08-08 Xerox Corporation Transfer of conductive particles
US4461563A (en) * 1982-10-22 1984-07-24 Xerox Corporation Copy sheet contamination prevention
US4737816A (en) * 1982-06-16 1988-04-12 Canon Kabushiki Kaisha Image transfer device
US5408300A (en) * 1991-10-18 1995-04-18 Mita Industrial Co., Ltd. Image-transfer and sheet-separation apparatus
US5724636A (en) * 1996-11-12 1998-03-03 Eastman Kodak Company Method and apparatus for transferring a toner image to a receiver sheet using an electrical bias
US5881347A (en) * 1997-04-21 1999-03-09 Eastman Kodak Company Biasing method and apparatus for electrostatically transferring an image
US20040156658A1 (en) * 2003-02-12 2004-08-12 Toshiba Tec Kabushiki Kaisha Image Forming Apparatus and Image Forming Method
EP2420898A1 (en) * 2010-08-18 2012-02-22 Ricoh Company, Ltd. Transfer device, image forming apparatus, and transfer method
US20130142531A1 (en) * 2011-12-06 2013-06-06 Naomi Sugimoto Transfer device and image forming apparatus using the same
US20130177329A1 (en) * 2012-01-11 2013-07-11 Shinya Tanaka Image forming apparatus
US20140079422A1 (en) * 2012-09-18 2014-03-20 Katsuhito Suzuki Transfer device, method for performing the same and image forming device

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5262026A (en) * 1975-11-17 1977-05-23 Toray Industries Method of transferring continuous recording medium for electrophotographic recording practice
JPS6016626B2 (ja) * 1977-04-08 1985-04-26 コニカ株式会社 カラ−電子写真転写方法
JPS57104168A (en) * 1980-12-19 1982-06-29 Canon Inc Cleaning device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2879395A (en) * 1955-06-08 1959-03-24 Haloid Xerox Inc Charging device
US2901374A (en) * 1955-05-04 1959-08-25 Battelle Development Corp Development of electrostatic image and apparatus therefor
US3714531A (en) * 1970-06-26 1973-01-30 Canon Kk Ac corona discharger

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2901374A (en) * 1955-05-04 1959-08-25 Battelle Development Corp Development of electrostatic image and apparatus therefor
US2879395A (en) * 1955-06-08 1959-03-24 Haloid Xerox Inc Charging device
US3714531A (en) * 1970-06-26 1973-01-30 Canon Kk Ac corona discharger

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4081212A (en) * 1974-11-18 1978-03-28 Oce-Van Der Grinten, N.V. System for electrostatically transferring powder images
US3921042A (en) * 1974-11-25 1975-11-18 Xerox Corp Electrostatic reproduction machine with improved corona generating device
FR2320586A1 (fr) * 1975-08-06 1977-03-04 Xerox Corp Dispositif de transfert d'image pour xerographie
US4105320A (en) * 1977-01-05 1978-08-08 Xerox Corporation Transfer of conductive particles
US4737816A (en) * 1982-06-16 1988-04-12 Canon Kabushiki Kaisha Image transfer device
US4461563A (en) * 1982-10-22 1984-07-24 Xerox Corporation Copy sheet contamination prevention
US5408300A (en) * 1991-10-18 1995-04-18 Mita Industrial Co., Ltd. Image-transfer and sheet-separation apparatus
US5689758A (en) * 1991-10-18 1997-11-18 Mita Industrial Co., Ltd. Image-transfer and sheet-separation apparatus
US5724636A (en) * 1996-11-12 1998-03-03 Eastman Kodak Company Method and apparatus for transferring a toner image to a receiver sheet using an electrical bias
US5881347A (en) * 1997-04-21 1999-03-09 Eastman Kodak Company Biasing method and apparatus for electrostatically transferring an image
US20040156658A1 (en) * 2003-02-12 2004-08-12 Toshiba Tec Kabushiki Kaisha Image Forming Apparatus and Image Forming Method
US20050036807A1 (en) * 2003-02-12 2005-02-17 Kabushiki Kaisha Toshiba Image forming apparatus and image forming method
US6862422B2 (en) * 2003-02-12 2005-03-01 Kabushiki Kaisha Toshiba Image forming apparatus and image forming method having pressing members for pressing a belt-like member
US6952552B2 (en) 2003-02-12 2005-10-04 Kabushiki Kaisha Toshiba Image forming apparatus and method that applies different voltages to pressing members
EP2420898A1 (en) * 2010-08-18 2012-02-22 Ricoh Company, Ltd. Transfer device, image forming apparatus, and transfer method
US8923716B2 (en) 2010-08-18 2014-12-30 Ricoh Company, Limited Transfer device, image forming apparatus, and transfer method
US20130142531A1 (en) * 2011-12-06 2013-06-06 Naomi Sugimoto Transfer device and image forming apparatus using the same
US9081335B2 (en) * 2011-12-06 2015-07-14 Ricoh Company, Limited Transfer device with transfer voltage unit and image forming apparatus using the same
US9335674B2 (en) 2011-12-06 2016-05-10 Ricoh Company, Limited Transfer device with transfer voltage unit and image forming apparatus using the same
US20130177329A1 (en) * 2012-01-11 2013-07-11 Shinya Tanaka Image forming apparatus
US9488937B2 (en) * 2012-01-11 2016-11-08 Ricoh Company, Ltd. Image forming apparatus
US20140079422A1 (en) * 2012-09-18 2014-03-20 Katsuhito Suzuki Transfer device, method for performing the same and image forming device
US9026019B2 (en) * 2012-09-18 2015-05-05 Ricoh Company, Limited Transfer device, method for performing the same and image forming device

Also Published As

Publication number Publication date
GB1370976A (en) 1974-10-23
DE2245848A1 (de) 1973-03-29
JPS5441904B2 (enrdf_load_stackoverflow) 1979-12-11
JPS4839034A (enrdf_load_stackoverflow) 1973-06-08

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