EP0578901A1 - Appareil d'impression électrophotographique - Google Patents

Appareil d'impression électrophotographique Download PDF

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Publication number
EP0578901A1
EP0578901A1 EP92830385A EP92830385A EP0578901A1 EP 0578901 A1 EP0578901 A1 EP 0578901A1 EP 92830385 A EP92830385 A EP 92830385A EP 92830385 A EP92830385 A EP 92830385A EP 0578901 A1 EP0578901 A1 EP 0578901A1
Authority
EP
European Patent Office
Prior art keywords
fixing unit
path
entrance
transfer station
transfer
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.)
Withdrawn
Application number
EP92830385A
Other languages
German (de)
English (en)
Inventor
Carlo Fare'
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.)
Bull HN Information Systems Italia SpA
Bull HN Information Systems Inc
Original Assignee
Bull HN Information Systems Italia SpA
Bull HN Information Systems Inc
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 Bull HN Information Systems Italia SpA, Bull HN Information Systems Inc filed Critical Bull HN Information Systems Italia SpA
Priority to EP92830385A priority Critical patent/EP0578901A1/fr
Publication of EP0578901A1 publication Critical patent/EP0578901A1/fr
Withdrawn legal-status Critical Current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
    • G03G15/65—Apparatus which relate to the handling of copy material
    • G03G15/6555—Handling of sheet copy material taking place in a specific part of the copy material feeding path
    • G03G15/657—Feeding path after the transfer point and up to the fixing point, e.g. guides and feeding means for handling copy material carrying an unfused toner image
    • 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
    • G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
    • G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
    • G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat
    • G03G15/2017—Structural details of the fixing unit in general, e.g. cooling means, heat shielding means
    • G03G15/2028—Structural details of the fixing unit in general, e.g. cooling means, heat shielding means with means for handling the copy material in the fixing nip, e.g. introduction guides, stripping means
    • 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
    • G03G15/6582—Special processing for irreversibly adding or changing the sheet copy material characteristics or its appearance, e.g. stamping, annotation printing, punching
    • 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
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00367—The feeding path segment where particular handling of the copy medium occurs, segments being adjacent and non-overlapping. Each segment is identified by the most downstream point in the segment, so that for instance the segment labelled "Fixing device" is referring to the path between the "Transfer device" and the "Fixing device"
    • G03G2215/00413—Fixing device

Definitions

  • the present inventions relates to an electrophotographic printing apparatus, more particularly of the face down type.
  • Electrophotographic printing apparatuses are known where an image carrier (generally a photosensitive drum), having a toner image formed therein by subjecting the image carrier to a selective radiation exposure followed by a developing operation, is continuously rotated at a peripheral speed equal to the advancement speed of a recording medium, usually paper, which is tangentially brought in contact with the image carrier along a generatrix of the image carrier or contact line.
  • an image carrier generally a photosensitive drum
  • a toner image formed therein by subjecting the image carrier to a selective radiation exposure followed by a developing operation is continuously rotated at a peripheral speed equal to the advancement speed of a recording medium, usually paper, which is tangentially brought in contact with the image carrier along a generatrix of the image carrier or contact line.
  • a corona electrostatic charge generator usually referred to as scorotron, is located in close proximity to the image carrier at the contact line so that the recording medium crosses the gap between the scorotron and the image carrier.
  • the effect of the scorotron is to electrostatically charge the recording medium so as to displace the toner from the image carrier and to attract it on the recording medium.
  • scorotron is also named transfer unit and the contact line of the image carrier and the paper, where transfer occurs is named transfer station.
  • the electrophotographic process is named as face-down or face up process because the toner adheres to the printing medium on the undersurface or the upward surface.
  • the recording medium moves along a predetermined path and reaches a fixing station, where by heat and pressure the toner is caused to melt and to permanently adhere to the recording medium.
  • the face down process offers the advantage of providing an ordered stacking of a plurality of recording medium sheets as they leave the fixing station, without need of turning over devices, or manual rearrangement.
  • the recording medium must be hold in position without contacting the underside surface and without subjecting it to shocks which could cause detaching of the toner from the medium.
  • the arrangement is however effective only at the extent the advancement speed imposed to the recording medium is the same at the transfer station and at the fixing unit.
  • the arrangement makes impossible to take into account the dimensional changes occurring in the recording medium due to the heating operation performed at the fixing station. It has been found that contrarily to any expectation, a contraction, rather than a dilatation occurs in proximity of the fixing station, the contraction being related in unpredictable way to the moisture content of the medium and to its thickness.
  • the recording medium may be subjected between the fixing unit and the transfer station, to a pull having a non uniform distribution resulting in permanent wrinkling of the medium leaving the fixing unit.
  • the guiding means of the invention comprises a grid plate providing a path some how divergent from a straight line connecting the transfer station and the entrance of the fixing unit and suction means which cause the medium to adhere to the grid at a variable extent, depending on the effective length of the medium portion interposed between the transfer station and the fixing unit, thus preventing any undesired pull increase.
  • the guiding means of the invention may be provided with ozone abating filters, thus combining two advantageous effects in a unitary arrangement.
  • the apparatus comprises a photocondutive drum 1 rotating in the direction of the arrow 2, a corona charger 3, with charges in uniform way the surface of the photoconductive drum, a scanning light beam generator 4, electronic control circuits 5, a developing unit 6 a paper feeding device 7, paper driving rollers 8, a corona discharger 9, a suction box 10, a fixing unit consisting in a rotating heating drum 11 and a pressure roller 12, discharging rollers 13, a cleaning blade 14 and a waste toner collector tank 15.
  • the apparatus is powered by a power supply 16 and the moving elements are driven by suitable motors not shown.
  • the photoconductive drum, uniformily charged by corotron 3 is selectively discharged by a modulated scanning light beam generated by unit 4 in the course of the photosensitive drum revolution.
  • Toner is selectively applied on the exposed or unexposed areas of the photosensitive drum, depending on the used (positive or negative) process, by the developing unit 6.
  • the developing unit 6 is basically a toner container having a rotating developing drum 61 which brings a controlled amount of toner in proximity of the photoconductive drum surface where it is selectively attracted and adhere thereto forming a toner image.
  • the rotation of drum 1 brings the toner image to a transfer station formed by the corona discharger 9 facing the surface of drum 1 along a predetermined generatrix or transfer line.
  • a recording medium usually a peper sheet, is pulled from a hopper 17 by the paper feeding roll 7, suitably driven, and fed along a feeding path where it is pinched by driving rollers 8 and further fed along an horizontal path at a speed equal to the peripheral speed of drum 1.
  • the paper sheet contacts the surface of drum 1 at the transfer line, were the action of the transfer unit 9 causes the toner to adhere to the underside surface of the paper.
  • the suction box 10 having a suction grid plate 18 extending along the horizontal path to be followed by the paper, exerts a pull on the paper, preventing its falling downward, owing to the paper intrinsecal weight.
  • rollers 8 The combined driving effect of rollers 8 and the holding action of the suction box, compel the paper to move along a nearly horizontal path and to reach the fixing unit where it is pinched between the heating drum 11 and the pressure roller 12 which further drive it to subsequent driving rollers 13 for discharging in a tray 19.
  • the contact line between the pressure roller 12 and the heating drum may be considered as the entrance of the fixing unit for the paper sheet.
  • the grid plate 18 which drives the paper sheet towards the entrance of the fixing unit is not in the same plane defined by the transfer line and the entrance of the fixing unit but slightly divergent therefrom, from the transfer line towards the fixing unit entrance.
  • the grid plate 18 is arranged according to a plane P tangent to drum 1 in B and the entrance A is located below such plane so that the grid plate 18 diverges from the plane AB of a small angle ⁇ , preferably in the order of 3-5 o .
  • the grid plate 18 extends towards the pressure roller 12 up to an edge shown as point C near to the surface of the pressure roller 11 and no further, to avoid interference with the pressure roller.
  • a paper sheet moving from the transfer station to the entrance of the fixing unit follows the grid plate 18 up to point C, then the leading edge of the paper sheet moving forward, interfere with the pressure roller 12, which smoothly bends downward the edge and brings it to the entrance of the fixing unit, with a direction substantially tangent in A to the heating drum.
  • the pressure roller 12 and the heating drum 11 are preferably arranged with their center axis defining a tangent plane T, common to both and containing point A, diverging from plane AB of an angle no lesser than and preferably comprised between ⁇ and 2 ⁇ .
  • the portion of the paper sheet comprised between A and B has clearly a length equal or greater than AC+CB, hence greater than AB.
  • the paper may partially and gradually detach from the grid plate and the difference in driving speed is compensated by a corresponding shorting of the paper portion comprised between A and B, without paper tensioning.
  • the distance AB is usually in the order of 5-10 cm and the paper path is greater than AC+CB and by the more, greater than the arc subtended by chord AB, and tangent in B to drum 1, it can be easily verified by geometrical considerations that the path followed by the paper sheet, for an angle ⁇ of 3 o or more, exceeds the length of the chord AB by more that 0,5 mm. and largely suffices to compensate for contraction of paper sheets occurring in practice, the paper sheets having a length in the order of 30-35 cm.
  • the suction box 10, containing a suction fan 30, is provided at the outlet with an active carbon filter 31.
  • the suction unit in addition to holding the paper sheet when present, provides a suction action for the air present in the apparatus, mostly the one surrounding the photosensitive drum 1, and performs an efficient abating function for the developed ozone.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
EP92830385A 1992-07-16 1992-07-16 Appareil d'impression électrophotographique Withdrawn EP0578901A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP92830385A EP0578901A1 (fr) 1992-07-16 1992-07-16 Appareil d'impression électrophotographique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP92830385A EP0578901A1 (fr) 1992-07-16 1992-07-16 Appareil d'impression électrophotographique

Publications (1)

Publication Number Publication Date
EP0578901A1 true EP0578901A1 (fr) 1994-01-19

Family

ID=8212141

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92830385A Withdrawn EP0578901A1 (fr) 1992-07-16 1992-07-16 Appareil d'impression électrophotographique

Country Status (1)

Country Link
EP (1) EP0578901A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102073252A (zh) * 2009-11-20 2011-05-25 精工爱普生株式会社 图像形成装置以及图像形成方法
CN102081329A (zh) * 2009-11-27 2011-06-01 精工爱普生株式会社 图像形成装置以及图像形成方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3578859A (en) * 1969-07-03 1971-05-18 Xerox Corp Mechanical stripping apparatus
US4017065A (en) * 1976-04-29 1977-04-12 Xerox Corporation Transfer-fusing speed compensation
EP0292359A1 (fr) * 1987-05-06 1988-11-23 Fujitsu Limited Appareil pour l'enregistrement d'images électrophotographiques
US4992835A (en) * 1989-06-12 1991-02-12 Ricoh Company, Ltd. Electrophotographic image forming apparatus
DE4032290A1 (de) * 1989-10-13 1991-04-25 Minolta Camera Kk Bilderzeugendes geraet

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3578859A (en) * 1969-07-03 1971-05-18 Xerox Corp Mechanical stripping apparatus
US4017065A (en) * 1976-04-29 1977-04-12 Xerox Corporation Transfer-fusing speed compensation
EP0292359A1 (fr) * 1987-05-06 1988-11-23 Fujitsu Limited Appareil pour l'enregistrement d'images électrophotographiques
US4992835A (en) * 1989-06-12 1991-02-12 Ricoh Company, Ltd. Electrophotographic image forming apparatus
DE4032290A1 (de) * 1989-10-13 1991-04-25 Minolta Camera Kk Bilderzeugendes geraet

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 8, no. 214 (P-304)(1651) 29 September 1984 & JP-A-59 095 562 ( MINOLTA CAMERA ) 1 June 1984 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102073252A (zh) * 2009-11-20 2011-05-25 精工爱普生株式会社 图像形成装置以及图像形成方法
CN102081329A (zh) * 2009-11-27 2011-06-01 精工爱普生株式会社 图像形成装置以及图像形成方法

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