US3620615A - Sheet stripping apparatus - Google Patents

Sheet stripping apparatus Download PDF

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Publication number
US3620615A
US3620615A US789030A US3620615DA US3620615A US 3620615 A US3620615 A US 3620615A US 789030 A US789030 A US 789030A US 3620615D A US3620615D A US 3620615DA US 3620615 A US3620615 A US 3620615A
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US
United States
Prior art keywords
xerographic
roller
sheet
copy
copy 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.)
Expired - Lifetime
Application number
US789030A
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English (en)
Inventor
Stewart W Volkers
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.)
Xerox Corp
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Xerox Corp
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 Xerox Corp filed Critical Xerox Corp
Application granted granted Critical
Publication of US3620615A publication Critical patent/US3620615A/en
Anticipated expiration legal-status Critical
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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
    • G03G15/65—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S271/00—Sheet feeding or delivering
    • Y10S271/90—Stripper

Definitions

  • ABSTRACT Apparatus for stripping a copy sheet electrostatically supporting a toner image from an oppositely charged xerographic surface.
  • the apparatus includes an electrically biased roller slightly spaced from the copy sheet in the stripping zone to effect the stripping. Contact between the roller and copy sheet neutralizes the sheet. Alternately, the neutralization may be effected by a corona discharge device.
  • This invention relates to xerography and in particular to apparatus for removing copy sheets, with transferred toner images from a xerographic surface.
  • a xerographic surface comprising a layer of photoconductive insulating material afi'lxed to a conductive backing is used to support latent electrostatic images.
  • the xerographic plate is electrostatically charged uniformly over its surface and then exposed to a light pattern of the image being reproduced to thereby discharge the charge in the areas where light strikes the layer.
  • the undischarged areas of the layer thus form an electrostatic charge pattern in conformity with the configuration of the original pattern;
  • the latent electrostatic image can then be developed by contacting it with a finely divided electrostatically attractable material such as a powder.
  • a finely divided electrostatically attractable material such as a powder.
  • Thepowder is held. in image areas by the electrostatic charge on the layer. Where the charge is greatest, the greatest amount of material is deposited; and where the charge is least, little or no material is deposited.
  • a powdered image is produced in conformity with a light image of the copy being reproduced.
  • the powder is subsequently transferred to a sheet of paper or other surface and suitably affixed thereto to form a permanent print.
  • the electrostatically attractable developing material commonly used in xerography comprises a pigmented resinous powder referred to herein as toner" and a larger granular material called carrier.”
  • the carrier is formed of, or coated with, a material removed in the triboelectric series from the toner so that a charge is generated between the powder and the granular carrier upon mutual interaction. Such charge causes the powder to adhere to the carrier.
  • the carrier besides providing a charge to the toner, permits mechanical control so that the toner can readily be brought into contact with the exposedxerographic surface for the development of the surface.
  • the powder particles are attracted to the electrostatic image from the granular material to produce a visible powdered image on the xerographic surface.
  • the transfer corotron which is a positive polarity when negatively charged toner is applied; deposits a positive charge on the copy paper.
  • the copy paper which is an insulator, retains the positive charge while inducing a negative charge in the nondischarged areas of the xerographic drum. This new charge orientation creates an electrostatic bond between the paper and drum.
  • the electrostatic bond therebetween must first be overcome either mechanically or electrostatically.
  • an air puffer When an air puffer is used to achieve this separation, at relatively high pressure of air must be employed to overcome the attraction of the paper for the drum.
  • high air pressures there is a tendcncy of such air to agitate the .unfused toner image on the paper and disrupt the image configurationof the toner on the copy sheet. This exhibits itself aspuffer smears on the final copy. This blowing of toner powder may also result .in toner dust problems throughout the functioning elements of the system. Furthermore.
  • the high pressure of air may repel the toner-bearing paper against the output conveyor with a tonerjarring force.
  • Another approach is to mechanically wedge the copy sheet from the drum. Mechanical fingers, however, have a tendency to scratch and abrade the xerographic surface.
  • the present invention is directed toremoving copy from a xerographic surface by electrostatically'attracting the charged copy sheet from the charged xerographic surface and then discharging the sheet so that it will not be reattracted thereto.
  • FIG. 1 is a schematic showing of a continuous and automatic xerographic reproducing machine utilizing sheet stripping apparatus constructed in accordance with the instant invention
  • FIG. 2 is an enlarged perspective. view of the xerographic drum, sheet feed elements and sheet stripping apparatusand FIG. 3 is a schematic showing of sheet stripping apparatus similar to that-of FIGS. 1 and 2 but showing an alternate embodiment .of the invention.
  • FIGS. 1 and 2 there is in FIGS. 1 and 2 an embodiment of. the subject invention in a suitable environment such as a continuous and automatic xerographic reproducing machine.
  • the machine has a xerographic surface 10 including a photoconductive layer on a conductive backing.
  • the surface is formed in the shape of a drum which is mounted on a shaft journaled in the frame of the machine to rotate in a direction as indicated by the arrow. This movement. causes the drum surface to move sequentially past a plurality of xerographic processing stations.
  • a charging station A at which a. uniform electrostatic charge is deposited on the photoconductive surface of the xerographic drum;
  • An exposure station B at which a light or radiation pattern of a copy to be reproduced is projected onto the drum surface to dissipate the drum charge in the exposed areas thereof thereby forming a latent electrostatic image of the copy to be reproduced;
  • a development station C at which the xerographic developing material including toner particles having an electrostatic charge opposite to that of the latent electrostatic image, are cascaded over the drum surface, whereby the toner particles adhere to the latent electrostatic image to form a xerographic powder image in the configuration of the copy being reproduced;
  • a transfer station D at which the xerographic powder image is electrostatically transferred from the drum surface to a transfer or support material and then removed from the drum for fusing the image onto the support material;
  • a drum cleaning and discharge station E at which the drum surface is brushed to remove residual toner particles remaining thereon after image transfer, and at which the drum surface is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon.
  • a sheet of a suitable backing material such as paper 12 is brought into contact with the xerographic surface by first sheet feeding mechanisms 14.
  • the xerographic surface 10 may be of any cylindrical endless shape and need not be a right-circular cylinder.
  • the sheet and drum then move at the same linear speed past a transfer corotron 16 which acts to electrostatically draw the toner image from the drum towards the paper.
  • the electrostatic charge emitted by the transfer corotron electrostatically tacks the paper to the drum.
  • the drum and paper then travel together to suitable mechanisms capable of removing the paper from the drum to thereby allow the toner-bearing paper to be transported away by second sheet feeding mechanisms 18.
  • the second sheet feeding mechanisms transport the tonerbearing paper past a fusing station 26 for the production of the final copy.
  • a stripping roller 20 is positioned across the xerographic drum slightly downstream from the transfer corotron.
  • the stripping roller is preferably mounted on an axis parallel with that of the xerographic surface adjacent the transfer corotron.
  • the roller is adapted to be rotated in a direction and at a speed concurrent with that of copy sheet material being removed from the drum. It can be driven off any convenient power source including the main serpentine drive of the reproducing machine.
  • the opposite end of the roller may be provided with an insulating collar formed of tape 22 or the like whereby the distance of separation between it and the xerographic drum may be kept constant.
  • the use of the insulator as the separating unit prohibits the flow of charge between the drum and the roller.
  • the distance between the roller and the drum is, for example, about 0.015 inch, slightly greater than the thickness ofa copy sheet to be removed. A nominal paper thickness for these parameters would be about 0.0035 inch. These distances prohibit the contacting of the roller with the copy sheet while it is still on the drum.
  • the roller is shown as a conductive member mounted to a suitable source of potential 24.
  • the potential on the roller is about 800 volts negative direct current, a voltage of about equal magnitude but opposite polarity from the charge on the copy sheet.
  • the roller 20 As the leading edge of the copy sheet, having a toner image electrostatically adhering thereto, is moved adjacent the stripping roller 20, the fields created therebetween cause the copy sheet to be electrostatically attracted toward the stripping roller away from the photoconductive surface. With a negative 800 volts on the roller 20 and a positive 800 volts on the copy sheet prior to separation, there is a resulting force sufficient to attract the paper from the xerographic surface. With the paper being removed from the drum it then contacts the roller whereupon the contact therebetween neutralizes the charge in the copy sheet. Due to the fact that the roller is rotating in the same direction and at the same linear speed as the copy sheet, the roller assists in transporting the image bearing sheet toward the fuser 26 for creating the permanent copy.
  • the neutralization of the copy sheet by the roller prohibits the reattraction of the copy sheet toward the drum since the charge in the copy sheet is not removed until this neutralization occurs. Prior to this neutralization, reattraction of the sheet to the drum is possible due to the electrical field therebetween. Due to the undesirability of having this reattraction which could have a toner jarring effect, the charge neutralizing roller is positioned adjacent the copy sheet.
  • the illustrative example of apparatus capable of carrying out the instant invention shows the sheet removing roller beneath the image bearing copy sheets and xerographic surface.
  • the force of gravity assists in permitting the copy sheet to move toward the roller. It is not, however, necessary that such relationship be retained in order to affect good stripping.
  • the transfer and stripping could adequately be carried out adjacent other segments of the photoconductive surface since the field created between the roller copy sheet can be made sufficient to electrostatically remove he copy sheet from the drum independent of gravity.
  • an additional corotron 28 is provided beyond the paper removing roller.
  • the purpose of this corotron, which may be connected to an alternating or negative source of potential 30 is to electrostatically neutralize the copy sheet as it is moved away from the xerographic surface toward the sheet attracting roller 20 while advancing toward the fuser 26. This is done as a further safeguard against the reattracting of the copy sheet to xerographic surface before its contact with, and neutralization by, biased roller.
  • roller need not, in fact, be a roller and need not, in fact, be rotating. It is sufficient, merely that the field creating member is in proximity to the photoconductive surface and charged copy sheet in the area adjacent where its removal is desired. The use of the roller merely provides a convenient way to neutralize and transport the stripped copy sheet away from the xerographic surface.
  • apparatus for producing xerographic copy which includes means for electrostatically charging a cylindrically shaped photoconductive surface, means to expose the charged surface to dissipate the charge in a patterned configuration of image and nonimage areas corresponding to the object to be reproduced, means to develop the exposed surface with charged toner particles, means to bring a backing sheet into contact with the photoconductive surface in registration with the developed charge pattern and means to electrostatically transfer the toner particles to the backing sheet, the improvement comprising means to electrostatically attract the backing sheet from the xerographic surface to thereby separate the toner-bearing backing sheet from the xerographic surface.
  • the lastmentioned means includes an electrically biased roller extending across the xerographic surface and spaced therefrom at a distance greater than the thickness of the backing sheet.
  • roller is mounted for rotation in the direction of movement of the copy sheet and xerographic surface.
  • roller is provided with insulating collars around each end thereof to keep the roller properly spaced from the xerographic surface.
  • the apparatus as set forth in claim 1 further including a corona discharge device to remove the charge from the copy sheet as the copy sheet moves away from the xerographic surface.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Cleaning In Electrography (AREA)
US789030A 1968-12-31 1968-12-31 Sheet stripping apparatus Expired - Lifetime US3620615A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US78903068A 1968-12-31 1968-12-31

Publications (1)

Publication Number Publication Date
US3620615A true US3620615A (en) 1971-11-16

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Family Applications (1)

Application Number Title Priority Date Filing Date
US789030A Expired - Lifetime US3620615A (en) 1968-12-31 1968-12-31 Sheet stripping apparatus

Country Status (4)

Country Link
US (1) US3620615A (enrdf_load_stackoverflow)
CA (1) CA927472A (enrdf_load_stackoverflow)
DE (1) DE1964199A1 (enrdf_load_stackoverflow)
GB (1) GB1290518A (enrdf_load_stackoverflow)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2257746A1 (de) * 1971-11-25 1973-05-30 Canon Kk Uebertragungsmedium-fuehrungsvorrichtung in einer elektrofotografischen kopiermaschine
JPS4888938A (enrdf_load_stackoverflow) * 1972-02-24 1973-11-21
JPS4890242A (enrdf_load_stackoverflow) * 1972-03-01 1973-11-24
US3809916A (en) * 1972-12-11 1974-05-07 Xerox Corp Dual cord interlock
JPS506786B1 (enrdf_load_stackoverflow) * 1970-12-02 1975-03-18
JPS5025543U (enrdf_load_stackoverflow) * 1973-06-28 1975-03-24
US3912257A (en) * 1974-01-02 1975-10-14 Eastman Kodak Co Detacking apparatus
US3955889A (en) * 1973-12-20 1976-05-11 Katsuragawa Denki Kabushiki Kaisha Apparatus for stripping receptor papers for use in electrophotographic machines
US3970381A (en) * 1973-02-26 1976-07-20 Xerox Corporation Method and apparatus for xerographic reproduction
FR2320586A1 (fr) * 1975-08-06 1977-03-04 Xerox Corp Dispositif de transfert d'image pour xerographie
US4013359A (en) * 1974-08-23 1977-03-22 Pitney-Bowes, Inc. Electrostatic copier including means for detaching paper from a photoconductor
JPS5263341A (en) * 1976-05-22 1977-05-25 Canon Inc Transfer guide for electrophotographic copying machine
US4027960A (en) * 1975-08-06 1977-06-07 Xerox Corporation Transfer system for electrostatic reproduction machine
USRE29632E (en) * 1965-10-11 1978-05-16 Canon Kabushiki Kaisha Electrophotographic device
US4145041A (en) * 1976-06-25 1979-03-20 Xerox Corporation Automatic document handling apparatus
JPS5465044A (en) * 1977-11-02 1979-05-25 Hitachi Metals Ltd Electrophotography device
US4159172A (en) * 1974-10-26 1979-06-26 Ricoh Company, Ltd. Transfer sheet separator for use with electrophotographic copying machine
US4219270A (en) * 1979-08-29 1980-08-26 Xerox Corporation Reproducing apparatus
US4350332A (en) * 1976-06-25 1982-09-21 Xerox Corporation Sheet handling apparatus
US4357092A (en) * 1979-09-14 1982-11-02 Konishiroku Photo Industry Co., Ltd. Image recording apparatus
US4641948A (en) * 1976-04-13 1987-02-10 Canon Kabushiki Kaisha Method of and device for preventing disturbance of unfixed visible image
US5515147A (en) * 1994-10-28 1996-05-07 Eastman Kodak Company Mechanism for substantially preventing trail edge smear of an image on a receiver member
US5523834A (en) * 1991-10-25 1996-06-04 Canon Kabushiki Kaisha Image forming apparatus having recording material separating means
US5557389A (en) * 1993-10-29 1996-09-17 Mita Industrial Co., Ltd. Device for separating a transfer paper utilizing a separation voltage
US5926683A (en) * 1995-03-22 1999-07-20 Canon Kabushiki Kaisha Image forming apparatus with two-potential-level electricity removing member
US6308040B1 (en) * 1999-09-01 2001-10-23 Fujitsu Limited Electrophotographic recorded device having excellent separating capabilities and method of transferring the recorded medium
US6366753B1 (en) * 1999-11-11 2002-04-02 Heidelberger Druckmaschinen Ag Charger wire tensioning mounting mechanism and method of using
US6900436B1 (en) 2000-10-14 2005-05-31 Eastman Kodak Company Corona wire tensioning mechanism

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5149732A (ja) * 1974-10-26 1976-04-30 Ricoh Kk Tenshahoshikidenshifukushakino shiitobunrisochi
GB2065558B (en) * 1979-12-10 1983-09-28 Ricoh Kk Sheet separating and conveying apparatus for use in electrophotographic copying machines
US4408863A (en) * 1980-07-21 1983-10-11 Ricoh Company, Ltd. Transfer medium separating device
US4412732A (en) * 1980-07-21 1983-11-01 Ricoh Company, Ltd. Transfer medium separating device
JPS57204072A (en) * 1981-06-10 1982-12-14 Ricoh Co Ltd Transferring and separating device for electrophotography

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2951443A (en) * 1956-12-27 1960-09-06 Haloid Xerox Inc Image reproduction
US3318212A (en) * 1965-09-20 1967-05-09 Xerox Corp Duplex xerographic reproduction
US3332328A (en) * 1965-03-01 1967-07-25 Xerox Corp Xerographic developer seal and process

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2951443A (en) * 1956-12-27 1960-09-06 Haloid Xerox Inc Image reproduction
US3332328A (en) * 1965-03-01 1967-07-25 Xerox Corp Xerographic developer seal and process
US3318212A (en) * 1965-09-20 1967-05-09 Xerox Corp Duplex xerographic reproduction

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE29632E (en) * 1965-10-11 1978-05-16 Canon Kabushiki Kaisha Electrophotographic device
JPS506786B1 (enrdf_load_stackoverflow) * 1970-12-02 1975-03-18
DE2257746A1 (de) * 1971-11-25 1973-05-30 Canon Kk Uebertragungsmedium-fuehrungsvorrichtung in einer elektrofotografischen kopiermaschine
JPS4888938A (enrdf_load_stackoverflow) * 1972-02-24 1973-11-21
JPS4890242A (enrdf_load_stackoverflow) * 1972-03-01 1973-11-24
US3809916A (en) * 1972-12-11 1974-05-07 Xerox Corp Dual cord interlock
US3970381A (en) * 1973-02-26 1976-07-20 Xerox Corporation Method and apparatus for xerographic reproduction
JPS5025543U (enrdf_load_stackoverflow) * 1973-06-28 1975-03-24
US3955889A (en) * 1973-12-20 1976-05-11 Katsuragawa Denki Kabushiki Kaisha Apparatus for stripping receptor papers for use in electrophotographic machines
US3912257A (en) * 1974-01-02 1975-10-14 Eastman Kodak Co Detacking apparatus
US4013359A (en) * 1974-08-23 1977-03-22 Pitney-Bowes, Inc. Electrostatic copier including means for detaching paper from a photoconductor
US4159172A (en) * 1974-10-26 1979-06-26 Ricoh Company, Ltd. Transfer sheet separator for use with electrophotographic copying machine
FR2320586A1 (fr) * 1975-08-06 1977-03-04 Xerox Corp Dispositif de transfert d'image pour xerographie
US4027960A (en) * 1975-08-06 1977-06-07 Xerox Corporation Transfer system for electrostatic reproduction machine
US4641948A (en) * 1976-04-13 1987-02-10 Canon Kabushiki Kaisha Method of and device for preventing disturbance of unfixed visible image
JPS5263341A (en) * 1976-05-22 1977-05-25 Canon Inc Transfer guide for electrophotographic copying machine
US4145041A (en) * 1976-06-25 1979-03-20 Xerox Corporation Automatic document handling apparatus
US4350332A (en) * 1976-06-25 1982-09-21 Xerox Corporation Sheet handling apparatus
JPS5465044A (en) * 1977-11-02 1979-05-25 Hitachi Metals Ltd Electrophotography device
US4219270A (en) * 1979-08-29 1980-08-26 Xerox Corporation Reproducing apparatus
US4357092A (en) * 1979-09-14 1982-11-02 Konishiroku Photo Industry Co., Ltd. Image recording apparatus
US5523834A (en) * 1991-10-25 1996-06-04 Canon Kabushiki Kaisha Image forming apparatus having recording material separating means
US5557389A (en) * 1993-10-29 1996-09-17 Mita Industrial Co., Ltd. Device for separating a transfer paper utilizing a separation voltage
US5515147A (en) * 1994-10-28 1996-05-07 Eastman Kodak Company Mechanism for substantially preventing trail edge smear of an image on a receiver member
US5926683A (en) * 1995-03-22 1999-07-20 Canon Kabushiki Kaisha Image forming apparatus with two-potential-level electricity removing member
US6308040B1 (en) * 1999-09-01 2001-10-23 Fujitsu Limited Electrophotographic recorded device having excellent separating capabilities and method of transferring the recorded medium
US6366753B1 (en) * 1999-11-11 2002-04-02 Heidelberger Druckmaschinen Ag Charger wire tensioning mounting mechanism and method of using
US6900436B1 (en) 2000-10-14 2005-05-31 Eastman Kodak Company Corona wire tensioning mechanism

Also Published As

Publication number Publication date
CA927472A (en) 1973-05-29
DE1964199A1 (de) 1970-07-16
GB1290518A (enrdf_load_stackoverflow) 1972-09-27

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