EP0568829A2 - Appareil de formation d'images - Google Patents

Appareil de formation d'images Download PDF

Info

Publication number
EP0568829A2
EP0568829A2 EP93105767A EP93105767A EP0568829A2 EP 0568829 A2 EP0568829 A2 EP 0568829A2 EP 93105767 A EP93105767 A EP 93105767A EP 93105767 A EP93105767 A EP 93105767A EP 0568829 A2 EP0568829 A2 EP 0568829A2
Authority
EP
European Patent Office
Prior art keywords
transfer
bias
photoconductive element
belt
sheet
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.)
Granted
Application number
EP93105767A
Other languages
German (de)
English (en)
Other versions
EP0568829B1 (fr
EP0568829A3 (fr
Inventor
Yuko Harasawa
Itaru Matsuda
Satoshi Takano
Hideo Yu
Yasunori Kawaishi
Hideki Kamiyama
Toshiaki Motohashi
Mitsuru Takahashi
Takashi Bisaiji
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.)
Ricoh Co Ltd
Original Assignee
Ricoh Co Ltd
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 Ricoh Co Ltd filed Critical Ricoh Co Ltd
Publication of EP0568829A2 publication Critical patent/EP0568829A2/fr
Publication of EP0568829A3 publication Critical patent/EP0568829A3/fr
Application granted granted Critical
Publication of EP0568829B1 publication Critical patent/EP0568829B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • 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
    • G03G15/65—Apparatus which relate to the handling of copy material
    • G03G15/6532—Removing a copy sheet form a xerographic drum, band or plate
    • G03G15/6535—Removing a copy sheet form a xerographic drum, band or plate using electrostatic means, e.g. a separating corona
    • 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
    • G03G15/1605—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 at least one intermediate support
    • 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
    • G03G15/1675—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 with means for controlling the bias applied in the transfer nip
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/16—Transferring device, details
    • G03G2215/1604—Main transfer electrode
    • G03G2215/1623—Transfer belt
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/16—Transferring device, details
    • G03G2215/1647—Cleaning of transfer member
    • G03G2215/1661—Cleaning of transfer member of transfer belt

Definitions

  • an image forming apparatus comprises a photoconductive element for forming a toner image thereon, a transfer belt movable in contact with the photoconductive element over a predetermined nip width for transporting a sheet to allow the toner image to be transferred from the photoconductive element to the sheet, a transfer bias applying device contacting said transfer belt at a position downstream of the photoconductive element for applying a predetermined bias to the transfer belt, and a potential gradient generating device having an elastic dielectric layer on a surface thereof and contacting a rear of the transfer belt in a position upstream of the photoconductive element for providing the transfer bias with a potential gradient such that an amount of transfer of the toner image from the photoconductive element to the sheet increases in a region upstream of the nip portion with respect to said transfer belt and terminating at a point where the photoconductive element and transfer belt contact each other.
  • an image forming apparatus comprises a photoconductive element for forming a toner image thereon, a transfer medium contacting the photoconductive element over a predetermined nip width in a transfer region and undergoing a step of transferring the toner image formed on the photoconductive element a plurality of times, a first electrode contacting the transfer medium at a position downstream of the transfer region, a second electrode contacting the transfer medium at a position upstream of the transfer region, and a potential gradient generating device for providing the transfer bias with a potential gradient by applying a transfer bias to the first electrode or both of the first and said second electrodes, and applying, when a toner is absent on the transfer medium, a bias of the same polarity as the toner to the second electrode or applying, when the toner is present on the transfer medium, a bias of opposite polarity to the toner to the second electrode, such that an amount of transfer of the toner image from the photoconductive element to the transfer medium increases in a region upstream of a transfer
  • the solenoid 9 is deenergized to retract the lever 10 and, therefore, the belt assembly including the belt 3 and rollers 4-7. As a result, the belt 3 is brought out of contact with the drum 1. This is to protect the drum 1 from deterioration while the transfer of a toner image is not performed.
  • FIG. 6 shows a fourth embodiment of the present invention which is similar to the third embodiment except for a variable power source 15 substituted for the power source 14.
  • the variable power source 15 applies a bias voltage lower than the bias voltage to the bias roller 5 to the bias roller 4 and at the same time as the voltage to the bias roller 5.
  • the power source 15 applies the same bias voltage as applied to the bias roller 5 to the bias roller 4.
  • the resulting potential distribution of the belt 3 is shown in FIG. 20.
  • the CPU 27 causes the power source 14 to start applying the bias voltage to the bias roller 4 at the same time as the power source 8 applies the bias voltage to the bias roller 5 via the load driver 31.
  • the bias rollers 4 and 5 inject charges into the sheet.
  • the toner image is stably transferred to the sheet at the rear of the leading end portion of the belt 3. So long as the humidity is lower than 70 %, the separation of the sheet from the drum 1 is satisfactory. Since the bias rollers 4 and 5 sequentially deposit a charge on the sheet, the toner image is stably transferred from the leading edge toward the trailing edge of the sheet at all times.
  • the color image sensor 109 is made up of blue (B), green (G) and red (R) color separating means and a CCD array or similar photoelectric transducer so as to read the three different colors at the same time.
  • B, G and R image signals from the image sensor 109 are converted to black (BK), cyan (C), magenta (M) and yellow (Y) color image data by an image processor, not shown, on the basis of their intensity levels.
  • the drum 112 is rotated and has the surface thereof uniformly charged by the main charger 121.
  • the color scanner 101 starts reading the document 103 to produce BK image data.
  • the unit 111 scans the charged surface of the drum 112 by a laser beam to electrostatically form a latent image thereon.
  • the latent image derived from the BK image data be referred to as a BK latent image.
  • latent images resulting from C, M and Y image data be referred to as a C latent image, an M latent image, and a Y latent image, respectively.
  • the developer on the sleeve 126a is brought to the inoperative position. This is completed after the trailing edge of the Y image has reached the Y developing unit 126.
  • the Y toner image formed on the drum 112 is transferred to the surface of the belt 128 being driven at the same speed as the drum 112.
  • the belt 128 may be moved in any one of the following three modes or any combination thereof (matching the copy size).
  • bias rollers 129 and 130 may each be provided with a desired reference potential which sets up the potential lower than 300 V between, the bias roller 129 and the contact point A, if desired.
  • FIG. 28 shows another alternative embodiment which is similar to the embodiment of FIG. 27 except that the bias roller 129 is electrically floating, and that a roller 151 is held in contact with the belt 128 at a position upstream of the bias roller 129.
  • the roller 151 is connected to ground.
  • the bias roller 129 increases the potential at the contact point A when electrically floating as illustrated than when connected to ground, it is possible to lower the transfer voltage to be applied to the bias roller 130.
  • the present invention provides an Image forming apparatus having various unprecedented advantages, as enumerated below

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Control Or Security For Electrophotography (AREA)
  • Color Electrophotography (AREA)
  • Fax Reproducing Arrangements (AREA)
  • Decoration By Transfer Pictures (AREA)
  • Combination Of More Than One Step In Electrophotography (AREA)
EP93105767A 1992-04-09 1993-04-07 Appareil de formation d'images Expired - Lifetime EP0568829B1 (fr)

Applications Claiming Priority (9)

Application Number Priority Date Filing Date Title
JP88916/92 1992-04-09
JP8891692 1992-04-09
JP8891692 1992-04-09
JP9070192 1992-04-10
JP9070192 1992-04-10
JP90701/92 1992-04-10
JP1015993 1993-01-25
JP10159/93 1993-01-25
JP01015993A JP3271811B2 (ja) 1992-04-09 1993-01-25 画像形成装置

Publications (3)

Publication Number Publication Date
EP0568829A2 true EP0568829A2 (fr) 1993-11-10
EP0568829A3 EP0568829A3 (fr) 1995-05-10
EP0568829B1 EP0568829B1 (fr) 2001-08-16

Family

ID=27278864

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93105767A Expired - Lifetime EP0568829B1 (fr) 1992-04-09 1993-04-07 Appareil de formation d'images

Country Status (5)

Country Link
EP (1) EP0568829B1 (fr)
JP (1) JP3271811B2 (fr)
KR (1) KR0145748B1 (fr)
DE (1) DE69330579T2 (fr)
ES (1) ES2161701T3 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0827043A3 (fr) * 1996-08-29 1998-05-13 Sharp Kabushiki Kaisha Dispositif de transfert
EP1429207A3 (fr) * 2002-09-19 2004-09-22 Ricoh Company Dispositif d'entraínement de bande, dispositif d'entraínement, procede et appareil de formation d'images.

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3488328B2 (ja) * 1996-02-02 2004-01-19 株式会社リコー 転写ベルト装置
JP2006047707A (ja) * 2004-08-05 2006-02-16 Ricoh Co Ltd 画像形成方法及び画像形成装置
JP5564993B2 (ja) * 2010-03-01 2014-08-06 株式会社リコー 画像形成装置

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58111960A (ja) * 1981-12-25 1983-07-04 Ricoh Co Ltd 転写紙分離装置
JPH0623900B2 (ja) * 1986-03-03 1994-03-30 ヤマウチ株式会社 画像形成装置において使用される転写ベルト
JPH02110586A (ja) * 1988-10-20 1990-04-23 Canon Inc 画像形成装置
US5172173A (en) * 1988-09-01 1992-12-15 Canon Kabushiki Kaisha Image forming device and transfer belt having contact-type electricity feeding means
DE68912889T2 (de) * 1988-11-08 1994-08-25 Canon Kk Bilderzeugungsgerät mit Kontrollmitteln für die elektrostatische Anziehung von Übertragungsmaterial.
JPH03186876A (ja) * 1989-12-16 1991-08-14 Canon Inc 画像形成装置

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0827043A3 (fr) * 1996-08-29 1998-05-13 Sharp Kabushiki Kaisha Dispositif de transfert
US5867760A (en) * 1996-08-29 1999-02-02 Sharp Kabushiki Kaisha Transfer device with an anisotropin conductive layer
EP1429207A3 (fr) * 2002-09-19 2004-09-22 Ricoh Company Dispositif d'entraínement de bande, dispositif d'entraínement, procede et appareil de formation d'images.
US7491142B2 (en) 2002-09-19 2009-02-17 Ricoh Company, Ltd. Belt driving device, driving device, method, image forming apparatus
US8226510B2 (en) 2002-09-19 2012-07-24 Ricoh Company, Ltd. Belt driving device, driving device, method, image forming apparatus

Also Published As

Publication number Publication date
DE69330579D1 (de) 2001-09-20
EP0568829B1 (fr) 2001-08-16
DE69330579T2 (de) 2002-06-27
KR930022160A (ko) 1993-11-23
ES2161701T3 (es) 2001-12-16
JPH06167896A (ja) 1994-06-14
KR0145748B1 (ko) 1998-09-15
EP0568829A3 (fr) 1995-05-10
JP3271811B2 (ja) 2002-04-08

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