EP0354310A1 - Procédé et dispositif pour le tirage électrophotographique - Google Patents

Procédé et dispositif pour le tirage électrophotographique Download PDF

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Publication number
EP0354310A1
EP0354310A1 EP89109619A EP89109619A EP0354310A1 EP 0354310 A1 EP0354310 A1 EP 0354310A1 EP 89109619 A EP89109619 A EP 89109619A EP 89109619 A EP89109619 A EP 89109619A EP 0354310 A1 EP0354310 A1 EP 0354310A1
Authority
EP
European Patent Office
Prior art keywords
toner
unit
developing
photosensitive member
electrophotographic printing
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.)
Ceased
Application number
EP89109619A
Other languages
German (de)
English (en)
Inventor
Koichi Kinoshita
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0354310A1 publication Critical patent/EP0354310A1/fr
Ceased legal-status Critical Current

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Classifications

    • 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
    • G03G15/1665—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 by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat
    • G03G15/167—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 by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat at least one of the recording member or the transfer member being rotatable during the transfer
    • 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
    • G03G13/06—Developing
    • G03G13/08—Developing using a solid developer, e.g. powder developer
    • G03G13/09—Developing using a solid developer, e.g. powder developer using magnetic brush
    • 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
    • G03G13/22—Processes involving a combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G13/24—Processes involving a combination of more than one step according to groups G03G13/02 - G03G13/20 whereby at least two steps are performed simultaneously
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
    • G03G21/0005—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium
    • G03G21/0064—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium using the developing unit, e.g. cleanerless or multi-cycle apparatus
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2221/00—Processes not provided for by group G03G2215/00, e.g. cleaning or residual charge elimination
    • G03G2221/0005—Cleaning of residual toner

Definitions

  • This invention relates to a method and apparatus for electrophotographic printing, more particularly an electrophotographic printing not requiring use of a cleaning device.
  • Prior art cleaning devices include use of a brush or a blade and a so-called two revolution device in which the polarity of a bias voltage applied to a developing device is reversed at an interval of two revolutions for effecting cleaning. It has long been desired to eliminate such cleaning device and method so as to simplify the construction and operation of the electrophotographic printing machine, but no effective method and device have been availabcle.
  • Japanese Laid Open Patent Specification No. 133179/1988 discloses an electrophotographic printing machine not using a cleaning device, this Laid Open Patent Specification does not teach the subject matter recited in the appending claims.
  • Another object of this invention is to provide a novel method and apparatus for electrophotographic printing wherein the developing operation and the cleaning operation proceed simultaneously without using a conventional cleaning device.
  • a still other object of this invention is to provide a novel method and apparatus for electrophotographic printing capable of using a toner having an extremely small diameter that cannot be used satisfactory.
  • an electrostatic printing method for use in an electrophotographic copying machine comprising a photosensitive member, a charging unit for charging the surface of the photosensitive member, a light image projecting unit for forming a latent image on the surface of the photosensitive member, a developing unit for developing a latent image by utilizing a dry type toner and a dry type carrier, a transfer printing unit for transfer printing a developed latent image onto a copying sheet, and a light projecting unit for projecting light onto the surface of the photoconductive member to erase hysteresis thereof, a charge polarity of the toner being the same as that of the charging unit, characterized in that the method comprises the step of using a toner and a carrier both having spherical configurations so as to cause a developing operation and a cleaning operation to proceed simultaneously at the developing unit.
  • an electrophotographic printing machine comprising a photosensitive member, a charging unit for charging the surface of the photosensitive member, a light image projecting unit for forming a latent image on the surface of the photosensitive member, a developing unit for developing the latent image by utilizing a dry type toner and a dry type carrier, a transfer printing unit for transfer printing a developed latent image onto a copying sheet, and a light projecting unit for projecting light onto the surface of the photoconductive member for erasing hysteresis thereof, the charge polarity of the toner being the same as that of the charging unit, characterized in that both of the toner and the carrier have spherical configurations so as to cause a developing operation and a cleaning operation proceed simultaneously at the developing unit.
  • the printer of this invention and the prior art printer are based on different theories. More particularly, where Se is used to prepare a photosensitive member of an electrophotographic copying machine, the surface of the photosensitive member is charged with a positive charge which is discharged by bright portions of a projected light image. A powder toner does not adhere to such discharged portions.
  • positive visualizing or developing method has been utilized in which a negatively charged toner is used.
  • negative developing method has been used by utilizing the fact that electric charge applied onto the portions of the photosensitive member which are irradiated with a light image discharges so as to decrease the surface charge and that the toner is caused to adhere to such discharged portions.
  • Another problem to be solved lies in that the residual toner hinders the light image projection of the next operating cycle.
  • the efficiency of transfer printing is generally 70 to 80%. This low transfer printing efficiency can be increased by improving the toner. However, even when the residual toner exists, care should be taken that the optical effect of the projected light image would not be impaired.
  • the average particle diameter of the toner is smaller by one order of magnitude than the diameter of the projected optical dots so that even when a residual toner of 20 to 30% exists, 70 to 80% of the surface of the photosensitive member would receive uniform light projection which is sufficiently large light exposure quantity.
  • the quality of the picture image is greatly influenced by the characteristic of the toner used. It is a third important feature of this invention to determine the characteristic of the toner.
  • Conditions (1) - (4) are arranged in accordance with their degree of importance.
  • the diameter of a photosensitive drum was 80 mm and the process speed was 114 mm/sec.
  • This embodiment is characterized in that a residual toner cleaning device is not used.
  • the operating timing of a transfer printing corona discharge device was adjusted such that while a copying paper is not being sent the transfer printing corona discharge device would not operate.
  • the carrier comprised by spherical iron powder having a mean particle diameter of 50 ⁇ , the surface of each spherical iron powder being magnetized.
  • a toner As a toner was used a spherical toner having a mean particle diameter of 7 ⁇ manufactured by Nippon Paint Co., Japan, the surface of each toner being covered by a polarizable high molecular weight substance.
  • the characteristics of the developing agent utilized in the embodiment 1 is characterized by the method of manufacturing the developing agent.
  • the iron powder consists essentially of a spherical iron powder produced by a carbon eliminating step of the iron manufacturing steps.
  • the surface of the iron powder is heat treated in a nitrogen atmosphere or covered by an anion resin.
  • the iron powder is characterized in that each powder has a substantially perfect spherical configuration and that the iron powder consists of nearly 100% iron. Of course, the surface of each powder should be extremely smooth.
  • the toner is also spherical.
  • Each toner comprises a spherical core obtained by polymerizing an organic substance containing a coloring agent, and uniformly covered by a cation resin of a small quantity.
  • both carrier and toner are spherical enables the developing agent to exhibit extremely uniform characteristics as well as an extremely satisfactory fluidity.
  • Spherical configuration means the widest actual moving area.
  • both carrier and toner are spherical irrespective of a state of admixture of the toner and carrier so that it is possible to establish a stable charged state.
  • the surface of the spherical toner is intentionally made irregular for increasing the cleaning efficiency.
  • no such measure is taken.
  • the toner can be charged uniformly and the particle diameter of the toner is substantially uniform; for example 7 ⁇ ⁇ 1 ⁇ .
  • Substantially 100% of the surface of each toner particle is covered by a cation resin.
  • the surface of the carrier is also homogeneous and smooth. The reason that the characteristics of the toner were carefully selected lies in that there is no toner charged to the opposite polarity.
  • toner particles charged to the opposite polarity present the toner would accumulate using the toner particles as nuclei, thus forming lumps.
  • toner particles having extremely different diameters the same disadvantageous phenomenon occurs, thereby not only decreasing resolution but also resulting in a nonuniform transfer printing. If one tries to improve the mean transfer printing efficiency, lumps described above result in poor transfer printing.
  • the residual toner not only prevents formation of high quality optical images, but also prevents cleaning which is effected at the same time as the development.
  • An unstable toner produced by crushing has such defects as a poor fluidity, a large particle diameter and a nonuniform charging caused by insufficient dispersion of a charge control agent (CCA).
  • CCA charge control agent
  • the carrier is not limited to an iron powder used in Embodiment 1.
  • a ferrite type carrier can also be used.
  • Spherical carriers having a mean particle diameter of 30 ⁇ or 20 ⁇ can readily be prepared.
  • spherical toners having a mean particle diameter of 30 ⁇ or 1 ⁇ can readily be prepared because the spherical toners are manufactured by a polymerization method.
  • the particle diameter of the toner does not present any problem. Accordingly, where an extremely fine toner having a mean particle diameter of 1 ⁇ , for example, is used and where the carrier particle diameter is selected to 20 ⁇ corresponding to the small mean diameter of the toner, the advantage of eliminating the cleaning device can be obtained.
  • the negative polarity corona discharge applied at the time of transfer printing has a negative effect upon the method and apparatus of this invention.
  • a method and construction for eliminating the negative effect will be discussed in the following embodiment 2.
  • an electrophotographic printer of this invention comprises a rotary drum 1 made of metal and carrying a photosensitive member, a corona discharge device 2 for applying a positive or negative charge onto the photosensitive member, means 11 for projecting an input light signal 3, a developing device 4, a transfer belt 5 for transferring a copying paper 7 to a transfer printing station at the contact position between rotary drum 1 and transfer belt 5, a corona discharge device 6 for charging the surface of transfer belt 5, a developer 8 for developing a toner image transfer printed onto the copying paper 7 and a light source 11 for erasing hysteresis of the photosensitive member, all the elements described above being disposed about the periphery of the photosensitive drum 1 in a manner well known in the art.
  • Fig. 2 shows a cross-sectional view of the transfer belt 5 which comprises a lining 9 made of electroconductive rubber and a flexible insulating thin layer 10.
  • the construction of embodiment 2 is different from that of embodiment 1 in that a transfer printing system shown by reference numerals as 5 and 6 is added.
  • the surface of the flexible insulating thin layer 10 is charged to a polarity opposite to that of the toner, by the corona discharge device 6 shown in Fig. 1.
  • the degree of charging is such that the surface potential of the insulating thin layer 10 would be about 2000 V, for example.
  • the thickness of the flexible insulating thin layer 10 is generally of the order of from 20 ⁇ to 70 ⁇ .
  • the operating principle of the transfer printing system shown in Fig. 1 is greatly different from the prior art transfer printing system in that according to this invention the toner is transferred to the copying paper from the surface of the photosensitive member by an electric field created by the charge presenting on the surface of the transfer belt, whereas according to the prior art transfer printing system the corona discharge is applied to the rear surface of the copying paper.. More particularly, the transfer printing effect by the transfer belt is static so that there is no fear of injecting an excessive charge into the toner caused by the bombardment of the corona discharge.
  • the transfer belt is constructed to be homogeneous and smooth, the electric field created by the charge on the surface of the transfer belt extends vertically to the belt surface and has a uniform intensity at all points. As a consequence, the residual toner remaining after the transfer printing can be reduced greatly. Since the decrease in the quantity of injection of the charge of the opposite polarity into the toner presenting on the surface of the photosensitive surface is not influenced by the presence or absence of a copying paper, in the embodiment 2 the charging of the transfer belt surface can be effected continuously irrespective of the feeding of copying paper without causing any trouble.
  • Embodiment 2 shows that it is useless to charge the toner presenting on the surface of the photosensitive member to an opposite polarity with reverse polarity corona discharge. Since a system is required in which ions at the transfer printing member would not be directly bombarded by the opposite polarity corona discharge, the invention is not limited to the transfer belt of the embodiment 2 and various modified systems can also be used. For example, the electric field can also be applied by a corona discharge or a roller from a relatively high resistance belt or from the rear surface of the insulating belt in the transfer printing device.
  • the performance isolating type transfer belt was used in embodiment 2 because such belt operates most stably.
  • the mechanical construction becomes simple. Accordingly, the disposition of the toner accumulating at the cleaning device and the mechanism for returning the accumulated toner to the developing device are not necessary. As a consequence, the percentage of returned toner becomes 100% so that the amount of toner that is used in vain is reduced to substantially zero.
  • an electrostatic latent image is formed by projecting a light image onto the surface of a photosensitive member which has been previously sensitized to a specific polarity, for example a positive polarity, and the electrostatic latent image is developed using a toner charged with a specific polarity, for example positive polarity.
  • a specific polarity for example a positive polarity
  • toner charged with a specific polarity for example positive polarity
  • the cleaning device which has been an essential element in the prior art printing machine is eliminated so that a novel method and apparatus of electrophotography can be provided wherein the developing operation and the cleaning operation can be proceeded simultaneously.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Cleaning In Electrography (AREA)
  • Dry Development In Electrophotography (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
EP89109619A 1988-08-12 1989-05-29 Procédé et dispositif pour le tirage électrophotographique Ceased EP0354310A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP201712/88 1988-08-12
JP63201712A JPH0251168A (ja) 1988-08-12 1988-08-12 クリーニングレス電子写真プリンティング方法

Publications (1)

Publication Number Publication Date
EP0354310A1 true EP0354310A1 (fr) 1990-02-14

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Application Number Title Priority Date Filing Date
EP89109619A Ceased EP0354310A1 (fr) 1988-08-12 1989-05-29 Procédé et dispositif pour le tirage électrophotographique

Country Status (2)

Country Link
EP (1) EP0354310A1 (fr)
JP (1) JPH0251168A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0400572A2 (fr) * 1989-05-31 1990-12-05 Kabushiki Kaisha Toshiba Appareil d'enregistrement
EP0540341A2 (fr) † 1991-10-30 1993-05-05 Oki Electric Industry Company, Limited Appareil et méthode de formation d'images
US5467176A (en) * 1993-06-24 1995-11-14 Fujitsu Limited Image forming method and apparatus with magnetic brush
EP0892319A1 (fr) * 1997-06-13 1999-01-20 Canon Kabushiki Kaisha Appareil électrophotographique, procédé pour génération d'image et unité de traitement
US6321059B1 (en) 1999-09-30 2001-11-20 Canon Kabushiki Kaisha Image forming apparatus
US6341207B1 (en) 1992-06-16 2002-01-22 Fujitsu Limited Cleanerless image forming method and system therefor
US7014969B2 (en) 2002-10-02 2006-03-21 Canon Kabushiki Kaisha Silica fine particle, toner, two-component developer and image forming method

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02271372A (ja) * 1989-04-12 1990-11-06 Konica Corp 画像形成装置
DE69535393T2 (de) * 1994-11-08 2007-10-31 Canon K.K. Bilderzeugungsverfahren und -gerät
JP3155915B2 (ja) 1994-11-18 2001-04-16 キヤノン株式会社 画像形成装置
DE69523119T2 (de) * 1994-11-28 2002-04-18 Canon K.K., Tokio/Tokyo Bilderzeugungsverfahren
JP3401629B2 (ja) * 1994-11-28 2003-04-28 キヤノン株式会社 画像形成方法及び該画像形成方法用トナー
JPH09251265A (ja) * 1996-01-09 1997-09-22 Fuji Xerox Co Ltd 画像形成装置およびそれに用いる電子写真感光体
EP0791861B1 (fr) * 1996-02-20 2003-05-07 Canon Kabushiki Kaisha Procédé de formation d'image
EP0911703B1 (fr) * 1997-10-21 2004-05-12 Canon Kabushiki Kaisha Appareil électrophotographique, méthode de formation d'images et unité de traitement
US6157801A (en) * 1998-06-11 2000-12-05 Canon Kabushiki Kaisha Magnetic particles for charging, charging member, charging device, process cartridge, and electrophotographic apparatus
JP3728166B2 (ja) 1999-02-12 2005-12-21 キヤノン株式会社 画像形成装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3628950A (en) * 1969-12-10 1971-12-21 Xerox Corp Improved method of removing the residual toner particles from a photoconductive surface
US4557992A (en) * 1984-03-26 1985-12-10 Konishiroku Photo Industry Co., Ltd. Developing method

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5537755A (en) * 1978-09-11 1980-03-15 Hitachi Ltd Production method of direct heating oxcide cathode
JPS5831359A (ja) * 1981-08-20 1983-02-24 Matsushita Electric Ind Co Ltd 画像記録装置
JPS63133179A (ja) * 1986-11-26 1988-06-04 Toshiba Corp 記録装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3628950A (en) * 1969-12-10 1971-12-21 Xerox Corp Improved method of removing the residual toner particles from a photoconductive surface
US4557992A (en) * 1984-03-26 1985-12-10 Konishiroku Photo Industry Co., Ltd. Developing method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0400572A2 (fr) * 1989-05-31 1990-12-05 Kabushiki Kaisha Toshiba Appareil d'enregistrement
EP0400572A3 (fr) * 1989-05-31 1992-05-06 Kabushiki Kaisha Toshiba Appareil d'enregistrement
EP0540341A2 (fr) † 1991-10-30 1993-05-05 Oki Electric Industry Company, Limited Appareil et méthode de formation d'images
US6341207B1 (en) 1992-06-16 2002-01-22 Fujitsu Limited Cleanerless image forming method and system therefor
US5467176A (en) * 1993-06-24 1995-11-14 Fujitsu Limited Image forming method and apparatus with magnetic brush
EP0892319A1 (fr) * 1997-06-13 1999-01-20 Canon Kabushiki Kaisha Appareil électrophotographique, procédé pour génération d'image et unité de traitement
US6285848B1 (en) 1997-06-13 2001-09-04 Canon Kabushiki Kaisha Electrophotographic apparatus, image forming method, and process cartridge for developing an image with toner containing an external additive
US6321059B1 (en) 1999-09-30 2001-11-20 Canon Kabushiki Kaisha Image forming apparatus
US7014969B2 (en) 2002-10-02 2006-03-21 Canon Kabushiki Kaisha Silica fine particle, toner, two-component developer and image forming method

Also Published As

Publication number Publication date
JPH0251168A (ja) 1990-02-21

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