US3620617A - Electrophotographic apparatus with improved toner transfer - Google Patents

Electrophotographic apparatus with improved toner transfer Download PDF

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Publication number
US3620617A
US3620617A US879073A US3620617DA US3620617A US 3620617 A US3620617 A US 3620617A US 879073 A US879073 A US 879073A US 3620617D A US3620617D A US 3620617DA US 3620617 A US3620617 A US 3620617A
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Prior art keywords
transfer
copy document
toner
transfer station
station
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US879073A
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English (en)
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Michael J Kelly
Myron F Shlatz
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International Business Machines Corp
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International Business Machines Corp
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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

  • the invention concerns electrophotographic apparatus provided with an optical photoconductive (OPC conveying means charged with an image pattern of toner and improved transfer means including an insulating transfer member for effecting a more positive transfer of toner from the OPC to a copy sheet.
  • the additional transfer member is a Mylar (Trademark of Du Pont & Co.) flap partially covering the transfer corona station and, in another case, a nylon or Dacron mesh covering the entire transfer station.
  • a negative potential is established on the transfer corona wires to charge the paper for effecting transfer of toner and, at the same time, to charge the additional transfer member to repel the paper and insure a closer contact with the OPC material.
  • Electrophotography using photoconductive insulating layers upon which an electrostatic image is formed has become embodied in a number of high-speed copying processes.
  • the photoconductive insulating layer is backed by a conductive layer and can be formed in the shape of a cylinder which is then rotated to. bring the electrophotographic element to a number of stations involved in carrying out the electrophotographic process.
  • the photoconductive insulating layer is first charged. by applying an electrical potential acrossit.
  • the charged, photoconductive layer is then exposed imagewiseto light and the electrical potential decays in the surface areas which are struck by light.
  • the dark.areas'of theprojected image retain their electrostatic charge, and the image is then developed by exposing the surface of the photoconductive layer to small charged marking particles known as toner particles.
  • the charged toner particles are attracted to the charged image areas of the photoconductive layer and thereby develop the electrostatic image.
  • the image .can then be transferred from the photoconductive layer to a copy sheet.
  • a number of ways are conventionally employed to develop the electrostatic image as is well known in the art. These include cascade development described, for example, in U.S. Pat. No. 2,618,552; powder cloud development described, for example, in U.S. Pat. No. 2,221,776; magnetic brush development described, for example, in U.S. Pat. No. 2,874,063; fur brush development, donor belt development, impression development and liquid spray development. Commonly used processes in commercial copying machines are cascade and magnetic brush development.
  • toner particles usually comprising a heat softenable resin binder material, for example, a natural or synthetic organic compound or polymer such as styrene polymers and copolymers, epoxy resins, rosin, rosin esters, polymers of acrylic and methacrylic acid esters such as those prepared by polymerizing such monomers as methyl methacrylate, butyl methacrylate, ethyl acrylate and mixtures thereof, Various physical and chemical combinations of such polymers can also be employed.
  • the resins are mixed with coloring matter, for example, carbon black so that a colored image can be easilyheat fused onto a copy sheet.
  • Other additives, such as plasticizers and anticaking agents can also be employed in the toner composition.
  • the image is transferred from the photoconductive layer to the copy sheet, such as plain paper.
  • the paper is placed in contact with the developed image on the element and the toner is transferred by an electrical charge and/or mechanical pressure applied to the paper.
  • the paper carrying the toner image is then stripped from the photoconductor.
  • a transfer corona station which has a relatively high negative potential applied to associated corona wires that charge the paper and enable the transfer of the toner image from the photoconductor element to the paper.
  • the toner and paper are than carried to a fuser where the toner is fused to the paper by heat.
  • the reproduction is carried to the output pocket and stored there.
  • the photoconductor which has some residual toner on it, is charged by a positive corona discharge device and then brushed to remove the majority of residual toner.
  • a number ofways of removing residual toner particles have been employed such as, for example, by physically contacting the surface of the photoconductofwith either a renewable web of fiber material or with the bristles of a rotating cylindrical brush-and, also, by contacting the photoconductor surface with high velocity air.
  • the removed particles are carried away from the cleaning station to a' suitable receptacle by providing an air pressure differential.
  • Light and/or'corona discharges can be employed to neutralize a portion of thecharge on the photoconductor prior to the time that it reaches thecleaning station sothat the particles are more easily removed.
  • the present arrangement improves transfer of toner from the photoconductor to thepaper. This leaves less residual toner on the photoconductor which is beneficial since the filming rate may be reduced and the cleaning bag life may be increased ona per cycle basis. 7 I
  • a lower amountof toner is likely to be used due to the fact that a lower toner concentration produces the same optical density of the characters. This is a direct function of the improved transfer efficiency realized.
  • the invention concerns electrophotographic apparatus having provision for an additional transfer member associated with a transfer corona station in a particular manner to improve the transfer of toner from the OPC element to'a copy sheet.
  • This is effected, in one case, by providing a flap member partially covering the transfer station or, in another case, by a mesh member that covers the entire station with the objective of providing some open space for the charge field normally established at the transfer station.
  • a supply source ordinarily establishes a relatively high negative potential on transfer corona wiresatthe transfer station. This same source is used to establish-a negative potential on the flap or the mesh, as the case may be.
  • the 'flap element is comprised of a Mylar material; and in the other case, themesh is formed of nylon or similar material.
  • the additional element tends to establish a higher negative charge on the reverse side of the copy paper, tending to attract the positively charged toner from the OPC to the paper in a more efficient fashion.
  • the mesh be oriented with the crossingthreads arranged at a 45 angle to the path of movement of the OPC element and copy paper. It has also been found that a Dacron mesh is quite suitable in the practice of the present invention. it is evident that some other angular relationship may be appropriate. A range of 20 to 70 for the'mesh could possibly be satisfactory.
  • a primary object of the present invention is to improve toner transfer from an OPC element to a copy sheet in an electrophotographic apparatus.
  • Another object of the present invention is to establish higher contact conditions at a transfer corona station for effecting a more efficient transfer of toner.
  • Another object of the invention is to reduce the residual toner on the OPC element after transfer thereby possibly reducing filming rate and increasing filter bag life.
  • a further object of the invention is to reduce the total amount of toner used in the system due to increased transfer efficiency, lowering the toner concentration necessary for acceptable copy density.
  • a particular object of the invention is to enhance the transfer of toner from a photoconductor element to paper to avoid streaking, dropout conditions, and improve overall quality of the copy.
  • FIG. 1 is a system diagram of an electrophotographic copying machine incorporating the transfer corona improvements 2 according to the present invention.
  • FIGS. 2a, 2b and 2c illustrate a prior transfer corona unit that is useful in explaining some of the problems encountered with such prior devices.
  • FIGS. 3a, 3b, and 30 represent a prior copy transfer condition showing streaking and dropout of toner, a transfer using a Mylar flap, and a transfer using a Dacron mesh, respectively.
  • FIGS. 40 and 4b illustrate a possible grid mat configuration i that is usable in practicing the present invention.
  • FIGS. 5a, 5b, and 5c illustrate a transfer corona station incorporating a Mylar flap in a particular embodiment of the invention.
  • FIGS. 60, 6b, and 6c illustrate a transfer corona device similar to that shown in FIGS. 5a, 5b, and 50, with the exception that a Dacron mesh is used instead of the Mylar flap.
  • FIG. 1 a typical electrophotographic copying device is schematically shown in conjunction with an embodiment of the invention.
  • the device has a control panel with power on switch 1, a stepdown counter 2, and copy counter dials 3.
  • a cylindrical drum 11 is mounted for rotation on a shaft and a photoconductive element 12 comprising photoconductive insulating layer 13 and a conductive backing layer is mounted on the outer periphery of drum 11.
  • photoconductive materials are conventionally employed in the photoconductive insulating layer 13, for example, amorphous or vitreous selenium, selenium alloys with tellurium and arsenic, cadmium selenide, cadmium sulfide, and zinc oxide in a resin binder.
  • Preexposure corona unit 17 deposits an electrical charge of the desired polarity on the photoconductive material while it is maintained in the dark.
  • Document 19 is held in place on a transparent plane 21 and an image of the document is projected onto the surface of the photoconductive insulating layer 13 by means of an illuminated scanning station 23 and optics 25.
  • the photoconductor is discharged at 27 in the portions struck by the light to form a charged image corresponding to document 19.
  • Drum 11 is rotated to bring the image to developer station 29 where finely divided charged toner particles are brought into contact with the charged image on the surface of photoconductive layer 13.
  • the developer station can employ a variety of different developer means, as previously mentioned, for example, a cascade developer unit, powder cloud developer unit or magnetic brush developer unit.
  • the developer station illustrated at 29 is a cascade developer unit wherein a two-component developer composition is caused to move across the surface of the charged image on the photoconductive layer 13.
  • the developer composition comprises relatively large carrier particles and relatively small heat fixable marking particles of toner as described, for example, in U.S. Pat. No. 2,618,552.
  • the toner particles are attracted to and cling to the charged areas of the photoconductive layer 13.
  • the toned image on the surface of photoconductive layer 13 is transferred to a plain paper sheet or web 33 with the assistance of a transfer corona unit 35 which charges the paper to a polarity opposite to that of the toner particles so that it will attract the toner away from the surface of the photoconductive layer 13.
  • the paper is then stripped from the photoconductive layer and passed to a heating unit 37 which acts to fuse and fix the toner image onto the paper.
  • a certain proportion of the toner particles remain on the photoconductive layer as a result of the fact that transfer efficiency to the paper is less than percent; and sometimes, because the length of paper copy sheet chosen is shorter than the length of the toned image on the drum, none of the toner is transferred from some image areas.
  • the rotating photoconductive layer is then passed into cleaning station 39 where it is contacted by a driven cylindrical cleaning and treatment brush 41 whose length corresponds approximately to the width of photoconductive layer 13 on the drum.
  • Brush 41 is mounted in a housing 43 and an air flow in the direction shown by the arrows is provided by a vacuum means 45 to carry off the removed toner to a filter bag 47.
  • a knockoff bar 49 aids in removing toner particles from the brush so that the brush remains relatively free from toner particles upon extended use.
  • Mounted inside the brush is a cylindrical fluorescent lamp 55 (usually about 1 watt per inch) connected to a conventional electrical power source which is not shown.
  • Brush 41 comprises strips 57 of fabric pile material of polytetrafluoroethylene such as is described in a copending U.S. application of Ray L. Dueltgen and Carl A. Queener, Ser. No. 762,952, filed Sept. 26, 1968, and assigned to the assignee of this invention.
  • Other materials can be used for the nap of the cleaning brush such as various types of furs, for example, beaver fur, gray fox fur, rabbit fur, and tiberlike synthetic materials such as nylon rayon or the like.
  • the synthetic fibers are woven or knit into conventional backing layers, such as, for example, cotton or polypropylene and cemented in place at the backing layer by a coating of latex,
  • the strips may be wound and secured to a transparent core of acrylic plastic.
  • Other light-transmitting plastics or glass can be employed for the core material.
  • Other methods of winding and securing to a core can also be employed.
  • the total amount of light reaching the photoconductor can be controlled to a useful degree by the percentage of core area left uncovered between strips.
  • FIG. 2a illustrates a configuration of a prior transfer corona station including a base member 60 with transfer corona wires 62 and 63 connected to a high negative potential at terminal 64.
  • FIG. 2 h simply illustrates a drum configuration for the OPC element and the prior transfer station 65 and indicates by arrows 66 and 67 the existence of maximum electrostatic pres sure due to the paper and catgut relationship.
  • the catgut strings 68 are provided on the base member 60 in order to inhibit paper from entering the open transfer station. These are shown further in FIG. 20. With such an arrangement, the catgut strings will tend to establish visible streaks in the copy sheet as it passes the transfer station in solid copy areas. It is felt that the streaking condition encountered with prior devices is not due to contact between the catgut strings and the paper, or the catgut would show signs of wear. It has been concluded that the streaking is probably primarily due to electrostatic enhancement factors rather than the contact noted.
  • FIG. 3a illustrates some of the streaking conditions that may exist in such a prior device. With the arrangements according to the present invention, copies are much clearer and the streaking condition is practically eliminated as shown in FIGS. 31; and 3c.
  • FIGS. 40 and 4b illustrate several configurationsthat are possible for insulating mats that have a high negative charge developed on them to repel the negatively charged paper and insure better pressure between the paper and the OPC drum element.
  • the mat element as can be seen in FIGS. 4a and 4b, is structured differently than the individual catgut strings discussed in connection with FIGS. 24, 2b, and 2c.
  • FIGS. 4a and 4b simply illustrate two possibleconfigurations of insulating mats with potential applied to these mats from the-same source that providespotential tothe corona wires, such as corona wires 70 and 71 in FIG. 4a.
  • Mat 75 includes a single centrally oriented portion 754 from which other elements extend at a slight angle to the direction of paper travel indicated by arrow 77;
  • Mat 80, FIG. 4b, on the other hand, has three parallel arranged portions with angularly positioned, elements. extending from them again at an angular relationship with respect to the path of travel of they paper copy also indicated by arrow 77.
  • the individual mats may be, of a Mylar, Dacron nylon or comparable material which is essentially an insulating material but which can acquire an electrostatic charge under appropriate conditions.
  • FIGS. 5a, 5b, and 5c are provided .with an insulating flap member 86 that may beof a material such as Mylar. It is seen in these figures that.the Mylar, having a thickness of perhaps 2 mils, is .positioned-in such a manner I that it partially. covers the transfer corona station opening in which the transfer wires 87 and 88 are provided. The clearance is established to enable the highly charged ions from within the transfer station to reach the underneath side of paper sheet 33 as it traverses the station adjacentthe OPC' drum element 11 and photoconductor material 13. With the arrangement shown, the Mylar flap is concurrently charged to a high negative potential along with the'charging of the paper 33. This creates two effects. It creates a strong repelling field.
  • Mylar flap is concurrently charged to a high negative potential along with the'charging of the paper 33. This creates two effects. It creates a strong repelling field.
  • FIGS. 6a, 6b, and 6c illustrate a transfer station 90 having tive ions from the transfer wires-to approach the underneathside of paper 33 and establishthe necessary charging conditions to attract the positively charged toner from the photoconductor. surface 13.
  • the insulating mesh attains a highly negative surface voltage, thus 'creating an additional. field approximately l0 to mils below the charged paper 33.
  • the additional field has the etfect .of causing the paper 33 to be repelled from-the nylon mesh because of the existence of negative charges on both the paper and the mesh; and also, the high negativetcharge on the mesh below the paper helps the toner to be attracted from the photoconductor surfacel3 of drum 11.
  • Electrophotographic apparatus for producing copy documents from master documents and having facilities for scanning a master document, imaging a photoconductor element, developing said image, and relatively moving said photoconductor element and a copy document with respect to a transfer station to effect transfer of toner particles from said photoconductor element to said copy document, said transfer station including at least one element positioned adjacent the path of movement-of a said copy document, the improvement comprising:
  • an auxiliarymember associated with and mounted at said transfer station; andcharging meansat said transfer station for chargingtsaid copy document thereby establishing a primary transfer field at saidtransfer station that is effective to attract toner particles from said photoconductor surface to said copy document, said charging means being further operable to chargesaid auxiliary member.
  • said charging means being further operable to chargesaid auxiliary member. in order to establish an auxiliary field at said transfer station for urging said copy document into closer contact with said photoconductor element to insure that a slight distance exists between. said copy document and said at least one transfer .station element thereby minimizing frictional contactbetween said copy document and said transfer station.
  • said auxiliary member comprises a Mylar flap coextensive with the transferstation and partially covering the field generatingarea thereby enabling passage of charge particles to,a.copy document while concurrently charging said auxiliary member.
  • said repelling transfer and auxiliary fields are of sufficiently high intensity than slight gap exists between a said copy document and said at least one transfer element at said transfer station, thereby minimizing :frictional contact between said copy document and; said at least one 8.
  • said mesh allows establishment of said primary transfer field through mesh openings for the purpose of effecting transfer of toner while concurrently charging said mesh grid in order to intensify the transfer operation by repelling the charge on said copy document as well as establishing a slight gap between said copy document and the transfer means thereby minimizing frictional contact between said copy document and said transfer station otherwise encountered during the transfer operation.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
US879073A 1969-11-24 1969-11-24 Electrophotographic apparatus with improved toner transfer Expired - Lifetime US3620617A (en)

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US87907369A 1969-11-24 1969-11-24

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US (1) US3620617A (enrdf_load_stackoverflow)
JP (1) JPS4916504B1 (enrdf_load_stackoverflow)
CA (1) CA938833A (enrdf_load_stackoverflow)
FR (1) FR2071749A5 (enrdf_load_stackoverflow)
GB (1) GB1266997A (enrdf_load_stackoverflow)
NL (1) NL7015036A (enrdf_load_stackoverflow)
SE (1) SE362154B (enrdf_load_stackoverflow)

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3783352A (en) * 1971-08-05 1974-01-01 Canon Kk Developing method for electrophotography
US3811048A (en) * 1972-09-12 1974-05-14 Xerox Corp Electrophotographic charging apparatus
JPS4955045U (enrdf_load_stackoverflow) * 1972-08-22 1974-05-15
JPS49105540A (enrdf_load_stackoverflow) * 1973-01-12 1974-10-05
US3851962A (en) * 1973-08-29 1974-12-03 Savin Business Machines Corp Electrostatic hold down apparatus
US3870541A (en) * 1972-01-27 1975-03-11 Xerox Corp Selective transfer of an electrostatic toner image
US3872307A (en) * 1972-02-21 1975-03-18 Canon Kk Discharger for electrophotographic copying apparatus
US3966199A (en) * 1975-03-17 1976-06-29 Xerox Corporation Belt transfer loading system
US3989007A (en) * 1973-12-07 1976-11-02 U.S. Philips Corporation Developing chamber for electrostatic latent images
US4013354A (en) * 1971-06-03 1977-03-22 Canon Kabushiki Kaisha Apparatus for separating transfer material in an electrostatic copying device
JPS52139431A (en) * 1976-05-14 1977-11-21 Xerox Corp Transfer apparatus
US4063810A (en) * 1975-01-13 1977-12-20 Xerox Corporation Color transparency reproducing machine
US4174170A (en) * 1976-12-16 1979-11-13 Minolta Camera Kabushiki Kaisha Conductive toner transfer photocopying machine
US4363550A (en) * 1979-12-06 1982-12-14 Tokyo Shibaura Denki Kabushiki Kaisha Recording sheet separating device in a transfer-type electronic copying machine
US4436412A (en) 1981-05-20 1984-03-13 Mita Industrial Company Limited Cleaning device for use on an electrostatic copying apparatus
US4575216A (en) * 1983-11-09 1986-03-11 Ricoh Company, Ltd. Electrophotographic copying apparatus including transfer charge corona and shield
US4673280A (en) * 1984-10-15 1987-06-16 Xerox Corporation Transfer charge control system
US4891680A (en) * 1988-04-25 1990-01-02 Xerox Corporation Transfer apparatus
US4903080A (en) * 1985-08-29 1990-02-20 Sharp Kabushiki Kaisha Copy paper separator for electrophotographic copying machine
US4922303A (en) * 1987-08-21 1990-05-01 Minolta Camera Kabushiki Kaisha Image forming apparatus with corona discharge device for transferring toner image
EP0382448A3 (en) * 1989-02-08 1991-06-12 Kabushiki Kaisha Toshiba Transfer device
US5101239A (en) * 1989-11-10 1992-03-31 Asahi Kogaku Kogyo Kabushiki Kaisha Transfer device for electrophotographic printer
US5541718A (en) * 1993-09-21 1996-07-30 Kabushiki Kaisha Toshiba Electrostatic image transfer device having a two level transfer voltage for improving image quality at leading and trailing edge regions
US5713063A (en) * 1994-08-03 1998-01-27 Kabushiki Kaisha Toshiba Electrostatic image transfer device having a two level transfer voltage for improving image quality at leading and trailing edge regions
US20020186990A1 (en) * 2001-05-02 2002-12-12 Andreas Dickhoff Device for charging and discharging of printing media in printing presses and copiers
EP1367460A2 (en) 2002-05-31 2003-12-03 Xerox Corporation Paper input guide for a transfer zone in a xerographic printing apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53129639A (en) * 1977-04-19 1978-11-11 Mita Industrial Co Ltd Method of and device for electrostatic copying

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US2777957A (en) * 1950-04-06 1957-01-15 Haloid Co Corona discharge device
US3332396A (en) * 1963-12-09 1967-07-25 Xerox Corp Xerographic developing apparatus with controlled corona means
US3470417A (en) * 1966-10-03 1969-09-30 Eastman Kodak Co Method of altering electrostatic charge on an insulating material
US3532494A (en) * 1969-09-08 1970-10-06 Gopal C Bhagat Solid area development in xerography employing an insulating screen in the charging step

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Publication number Priority date Publication date Assignee Title
US2777957A (en) * 1950-04-06 1957-01-15 Haloid Co Corona discharge device
US3332396A (en) * 1963-12-09 1967-07-25 Xerox Corp Xerographic developing apparatus with controlled corona means
US3470417A (en) * 1966-10-03 1969-09-30 Eastman Kodak Co Method of altering electrostatic charge on an insulating material
US3532494A (en) * 1969-09-08 1970-10-06 Gopal C Bhagat Solid area development in xerography employing an insulating screen in the charging step

Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4013354A (en) * 1971-06-03 1977-03-22 Canon Kabushiki Kaisha Apparatus for separating transfer material in an electrostatic copying device
US3783352A (en) * 1971-08-05 1974-01-01 Canon Kk Developing method for electrophotography
US3870541A (en) * 1972-01-27 1975-03-11 Xerox Corp Selective transfer of an electrostatic toner image
US3872307A (en) * 1972-02-21 1975-03-18 Canon Kk Discharger for electrophotographic copying apparatus
JPS4955045U (enrdf_load_stackoverflow) * 1972-08-22 1974-05-15
US3811048A (en) * 1972-09-12 1974-05-14 Xerox Corp Electrophotographic charging apparatus
JPS49105540A (enrdf_load_stackoverflow) * 1973-01-12 1974-10-05
US3850519A (en) * 1973-01-12 1974-11-26 Xerox Corp Xerographic image transfer apparatus
US3851962A (en) * 1973-08-29 1974-12-03 Savin Business Machines Corp Electrostatic hold down apparatus
US3989007A (en) * 1973-12-07 1976-11-02 U.S. Philips Corporation Developing chamber for electrostatic latent images
US4063810A (en) * 1975-01-13 1977-12-20 Xerox Corporation Color transparency reproducing machine
US3966199A (en) * 1975-03-17 1976-06-29 Xerox Corporation Belt transfer loading system
JPS52139431A (en) * 1976-05-14 1977-11-21 Xerox Corp Transfer apparatus
US4110024A (en) * 1976-05-14 1978-08-29 Xerox Corporation Transfer assembly for electrostatic transfer of a toner image from a curvilinear recording surface
US4174170A (en) * 1976-12-16 1979-11-13 Minolta Camera Kabushiki Kaisha Conductive toner transfer photocopying machine
US4363550A (en) * 1979-12-06 1982-12-14 Tokyo Shibaura Denki Kabushiki Kaisha Recording sheet separating device in a transfer-type electronic copying machine
US4436412A (en) 1981-05-20 1984-03-13 Mita Industrial Company Limited Cleaning device for use on an electrostatic copying apparatus
US4575216A (en) * 1983-11-09 1986-03-11 Ricoh Company, Ltd. Electrophotographic copying apparatus including transfer charge corona and shield
US4673280A (en) * 1984-10-15 1987-06-16 Xerox Corporation Transfer charge control system
US4903080A (en) * 1985-08-29 1990-02-20 Sharp Kabushiki Kaisha Copy paper separator for electrophotographic copying machine
US4922303A (en) * 1987-08-21 1990-05-01 Minolta Camera Kabushiki Kaisha Image forming apparatus with corona discharge device for transferring toner image
US4891680A (en) * 1988-04-25 1990-01-02 Xerox Corporation Transfer apparatus
US5138396A (en) * 1989-02-08 1992-08-11 Kabushiki Kaisha Toshiba Device for preventing paper from falling in a transfer device for electrophotographic recorders
EP0382448A3 (en) * 1989-02-08 1991-06-12 Kabushiki Kaisha Toshiba Transfer device
US5101239A (en) * 1989-11-10 1992-03-31 Asahi Kogaku Kogyo Kabushiki Kaisha Transfer device for electrophotographic printer
US5541718A (en) * 1993-09-21 1996-07-30 Kabushiki Kaisha Toshiba Electrostatic image transfer device having a two level transfer voltage for improving image quality at leading and trailing edge regions
US5713063A (en) * 1994-08-03 1998-01-27 Kabushiki Kaisha Toshiba Electrostatic image transfer device having a two level transfer voltage for improving image quality at leading and trailing edge regions
US20020186990A1 (en) * 2001-05-02 2002-12-12 Andreas Dickhoff Device for charging and discharging of printing media in printing presses and copiers
US6668154B2 (en) * 2001-05-02 2003-12-23 Nexpress Solutions Llc Device for charging and discharging of printing media in printing presses and copiers
EP1367460A2 (en) 2002-05-31 2003-12-03 Xerox Corporation Paper input guide for a transfer zone in a xerographic printing apparatus
US6687479B2 (en) 2002-05-31 2004-02-03 Xerox Corporation Paper input guide for a transfer zone in a xerographic printing apparatus

Also Published As

Publication number Publication date
DE2057494A1 (de) 1971-06-09
FR2071749A5 (enrdf_load_stackoverflow) 1971-09-17
GB1266997A (enrdf_load_stackoverflow) 1972-03-15
CA938833A (en) 1973-12-25
NL7015036A (enrdf_load_stackoverflow) 1971-05-26
DE2057494B2 (de) 1976-04-15
SE362154B (enrdf_load_stackoverflow) 1973-11-26
JPS4916504B1 (enrdf_load_stackoverflow) 1974-04-23

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