US3817615A - Device for preventing soiling of the trailing end portion of a transfer sheet - Google Patents

Device for preventing soiling of the trailing end portion of a transfer sheet Download PDF

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Publication number
US3817615A
US3817615A US00316100A US31610072A US3817615A US 3817615 A US3817615 A US 3817615A US 00316100 A US00316100 A US 00316100A US 31610072 A US31610072 A US 31610072A US 3817615 A US3817615 A US 3817615A
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United States
Prior art keywords
transfer
printing sheet
electrically conducting
printing
electrostatic latent
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Expired - Lifetime
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US00316100A
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English (en)
Inventor
T Adachi
K Kasuya
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Ricoh Co Ltd
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Ricoh Co Ltd
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Publication date
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Publication of US3817615A publication Critical patent/US3817615A/en
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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
    • G03G15/18—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a charge pattern

Definitions

  • a photosensitive drum serving as an image forming member is produced by providing a photoconductive material layer on a drum made of metal or other electrically conducting material, and an electrostatic latent image is formed on the photoconductive material layer of the photosensitive drum by charging and exposing the same to an optical image of an original.
  • a dielectric layer is provided on an electrically conducting material layer to provide a transfer-printing sheet which is brought into intimate contact with the electrostatic latent image bearing surface of the photosensitive drum and then stripped off therefrom so as to effect transferprinting of the electrostatic latent image on the transfer-printing sheet.
  • the electrostatic latent image transfer-printing method described has a disadvantage in that, if the electrically conducting material layer forming a part of the transfer-printing sheet has a relatively high resistance value or if the transfer-printing sheet is fed at high speed in order to increase efficiency by effecting transfer-printing at high speed, the trailing end portion of the transfer-printing sheet gets soiled for an extent of about several to several scores of millimeters due to adhesion of the toner in a greater quantity'than is necessary when the transfer-printed electrostatic latent imageis developed.
  • the image forming member may be in any other form, such for example as in sheet form, and need not be in drum form as described.
  • a photosensitive drum 1 is produced by providing an electrically conducting drum 2 made of aluminum, copper or the like with a photoconductive material layer 3 by coating its peripheral surface with selenium, zinc oxide, poly-N-vinyl carbazole or other photoconductive material. Photosensitive drum 1 is supported by a shaft 4 for rotation in the direction of an arrow a.
  • the peripheral surface of photosensitive drum 1 is electrically charged by means of a charger 8 comprising a wire electrode 7 on which a high bias voltage is impressed by a power source 6, and exposed by slit exposing means 13 comprising a projection lens 9, reflector l and slit member 11 formed with a slit S to an optical image of an original 14 moving on an original support surface 13 in synchronizm with the rotation of photosensitive drum 1.
  • a charger 8 comprising a wire electrode 7 on which a high bias voltage is impressed by a power source 6, and exposed by slit exposing means 13 comprising a projection lens 9, reflector l and slit member 11 formed with a slit S to an optical image of an original 14 moving on an original support surface 13 in synchronizm with the rotation of photosensitive drum 1.
  • a transfer-printing roller 15 made as of electrically conducting rubber produced by incorporating carbon black or the like in rubber is maintained in light contact with a lower portion of the periphery of photosensitive drum 1.
  • a transfer sheet 16 is fed between the peripheral surfaces of photosensitive drum 1 and transferprinting roller 15 by a pair of feed rollers 17.
  • Transferprinting sheet 6 comprises an electrically conducting material layer 16a and a dielectric layer 16b made of polyvinyl chloride, a copolymer of vinyl chloride and vinyl acetate or the like and disposed above electrically conducting material layer as shown in FIG. 2.
  • transfer-printing sheet 16 Upon being fed by the pair of feed rollers 17 between photosensitive drum 1 and roller 15, transfer-printing sheet 16 has its dielectric layer 16b brought into intimate contact with the electrostatic latent image on the peripheral surface of drum 1 so that the latent image on the drum periphery may be transferred to the dielectric layer of transfer-printing sheet 16, and then sheet 16 is stripped off from the drum periphery by a stripper 18 and conveyed to a developing device 20 by a pair of conveyor rollers 19 comprising rollers 19a and 19b.
  • Developing device 20 as shown comprises a developing liquid tank 21 containing therein a developing liquid 22 and having upper and lower fins 23 and 24, respectively, provided in the developing liquid for guiding transfer-printing sheet 16 in its movement through the developing liquid 22 in developing liquid tank 21 to render the electrostatic latent image thereon visible. After having its electrostatic latent image developed into a visible image, transfer-printing sheet 16 is discharged from tank 21 by a pair of squeeze and conveyor rollers 25.
  • the developing device may be of other forms than the device shown, such for example as other types of developing device of the wet developer type or a developing device of any known dry developer type.
  • the present practice is to impress a voltage of an opposite charge to the electrostatic latent image on transfer roller 15 by a power source 26 or to ground transfer-printing sheet 15 to achieve satisfactory results in effecting transfer-printing.
  • An attempt is made to achieve electric balancing of transfer-printing sheet 16 by using a roller of an electrically conducting material as one roller 19b of the pair of rollers 19 and grounding it so that the electrically conducting material layer 16a of transfer-printing sheet 16 in contact with it is grounded.
  • transfer-printing roller 15 When transfer-printing roller 15 is disposed nearer to the stripper 18, transfer-printing sheet 16 is hard to soil;
  • This invention has as its object the provision of a device for preventing soiling of the trailing end portion of a transfer-printing sheet due to overcharging by impressing a bias voltage, of the same charge as an electrostatic. latent image formed on an image fomiing member, on a portion of an electrically conducting material layer of the transfer-printing sheet disposed near a position in which the dielectric layer of the transferprinting sheet is stripped off from the dielectric layer of the image forming member.
  • a voltage of the same .charge as the electrostatic latent image formed on the image forming member is impressed on the portion of the electrically conducting material layer of the transfer-printing sheet which is disposed in a position in which the transfer-printing sheet is released from engagement with the image forming member and a transfer-printing roller or near to a stripper, so that overcharging of the trailing end portion of the transferprinting sheet can be prevented at all times and soiling thereof can be prevented.
  • the portion of the electrically conducting material layer disposed at the trailing end portion of transfer sheet 16 is charged oppositely to the electrostatic latent image formed on the dielectric layer 16b in a larger amount than is consistent with the electric potential at the electrostatic latent image due to the influence of a residual potential on photo-sensitive drum 1.
  • the amount of the charge of opposite sign to the electrostatic latent image is greater when the speed at which the transfer-printing sheet is released from engagement with the transfer-printing roller is higher.
  • the trailing end portion of the electrically conducting material layer of the transfer-printing sheet is excessively charged and performs the role of an opposite electrode when the latent image is developed, so that it promotes adhesion of toner to the dielectric layer 16b and causes soiling to occur.
  • This phenomenon may be considered as follows:
  • the potential V acts as a bias voltage when the electrostatic latent image is transferredfrom the photosensitive drum to the transfer-printing sheet.
  • soiling of the trailing end portion of the transfer-printing sheet can beprevented by impressing a voltage of the same charge as the electrostatic latent image on the portion of the electrically conducting material layer of the transfer-printing sheet which is disposed in a position in which the transfer-printing sheet is released from engagement with the photosensitive drum and the transfer printing roller.
  • FIG. 4 shows one embodiment of the invention which comprises voltage impressing means comprising a power source 27 and which is incorporated in the apparatus shown in FIG. 1 for impressing a voltage in a range of several scores to several hundreds of volts of the same charge as the electrostatic latent image on conveyor roller 19b, so as to prevent soiling of the trailing end portion of the transfer-printing sheet.
  • a bias voltage may be impressed on a guide plate 28 (see FIG. 5) of an electrically conducting material disposed in the vicinity of transfer-printing roller 15 in place of on conveyor roller 19b.
  • Other well-known means than the means described herein may be used as the voltage impressing means.
  • electrically conducting conveyor roller 19b is made of electrically conducting rubber or metal.
  • the invention can have application in a transferprinting method in which a dielectric layer is provided on the electrically conducting drum for forming thereon an electrostatic latent image as by means of a contact electrode, in place of using photosensitive drum 1.
  • the photosensitive drum or the aforementioned drum formed with the dielectric layer may be in sheet form in place of drum form.
  • the electrically conducting material layer may be made, not of metal, but of a sheet of paper or plastic treated to render it electrically conducting by applying electrically conducting rubber to its surface or laminating an aluminum sheet to it or a sheet of paper made by incorporating an electrically conducting material paper stock.
  • an electrophotographic reproduction device of the transfer-printing type in which an electrostatic latent image is formed on the dielectric surface of an image forming member having a dielectric layer on an electrically conducting material layer, and the dielectric surface of a transfer-printing sheet having a dielectric layer provided on an electrically conducting material layer is brought into intimate contact with the electrostatic latent image bearing surface of the image forming member and then stripped off to effect transfer-printing of the electrostatic latent image on the transfer-printing sheet
  • the improvement comprising voltage impressing means including a power source for impressing a bias voltage of the same charge as the 3,817,615 6 electrostatic latent image on a portion of the electri- 3.
  • fer-printing sheet due to overcharging can be pre- 5.
  • age impressing means comprises a transfer-printing 6.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Dot-Matrix Printers And Others (AREA)
  • Impression-Transfer Materials And Handling Thereof (AREA)
US00316100A 1971-12-28 1972-12-18 Device for preventing soiling of the trailing end portion of a transfer sheet Expired - Lifetime US3817615A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47000364A JPS5136072B2 (it) 1971-12-28 1971-12-28

Publications (1)

Publication Number Publication Date
US3817615A true US3817615A (en) 1974-06-18

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Application Number Title Priority Date Filing Date
US00316100A Expired - Lifetime US3817615A (en) 1971-12-28 1972-12-18 Device for preventing soiling of the trailing end portion of a transfer sheet

Country Status (3)

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US (1) US3817615A (it)
JP (1) JPS5136072B2 (it)
GB (1) GB1415875A (it)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3994579A (en) * 1975-05-14 1976-11-30 Xerox Corporation Transfer system for electrophotographic printing
US4006983A (en) * 1973-10-29 1977-02-08 Electroprint, Inc. Electrostatic color printing systems using modulated ion streams
US4055380A (en) * 1975-10-29 1977-10-25 Xerox Corporation Transfer charge maintaining system
US4057339A (en) * 1975-01-07 1977-11-08 Minolta Camera Kabushiki Kaisha Electrostatic latent image transfer type copying apparatus
US4159172A (en) * 1974-10-26 1979-06-26 Ricoh Company, Ltd. Transfer sheet separator for use with electrophotographic copying machine
US4235548A (en) * 1975-01-07 1980-11-25 Minolta Camera Kabushiki Kaisha Electrostatic latent image transfer type copying apparatus
US4607940A (en) * 1983-12-22 1986-08-26 Rhone-Poulenc Systemes Reversed development electrophotographic reproduction process and apparatus
US5276489A (en) * 1989-09-16 1994-01-04 Canon Kabushiki Kaisha Image forming apparatus with transfer roller with guide means which adjusts to movements of the roller

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS53166078U (it) * 1977-06-03 1978-12-26

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3147679A (en) * 1961-12-18 1964-09-08 Ibm Electrostatic image transfer processes and apparatus therefor
US3240596A (en) * 1961-07-28 1966-03-15 Ibm Electrophotographic processes and apparatus
US3345925A (en) * 1963-01-03 1967-10-10 Scm Corp Electrostatic printing and developing apparatus
US3630608A (en) * 1968-11-14 1971-12-28 Pitney Bowes Sage Inc High-speed copier

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3240596A (en) * 1961-07-28 1966-03-15 Ibm Electrophotographic processes and apparatus
US3147679A (en) * 1961-12-18 1964-09-08 Ibm Electrostatic image transfer processes and apparatus therefor
US3345925A (en) * 1963-01-03 1967-10-10 Scm Corp Electrostatic printing and developing apparatus
US3630608A (en) * 1968-11-14 1971-12-28 Pitney Bowes Sage Inc High-speed copier

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006983A (en) * 1973-10-29 1977-02-08 Electroprint, Inc. Electrostatic color printing systems using modulated ion streams
US4159172A (en) * 1974-10-26 1979-06-26 Ricoh Company, Ltd. Transfer sheet separator for use with electrophotographic copying machine
US4057339A (en) * 1975-01-07 1977-11-08 Minolta Camera Kabushiki Kaisha Electrostatic latent image transfer type copying apparatus
US4235548A (en) * 1975-01-07 1980-11-25 Minolta Camera Kabushiki Kaisha Electrostatic latent image transfer type copying apparatus
US3994579A (en) * 1975-05-14 1976-11-30 Xerox Corporation Transfer system for electrophotographic printing
US4055380A (en) * 1975-10-29 1977-10-25 Xerox Corporation Transfer charge maintaining system
US4607940A (en) * 1983-12-22 1986-08-26 Rhone-Poulenc Systemes Reversed development electrophotographic reproduction process and apparatus
US5276489A (en) * 1989-09-16 1994-01-04 Canon Kabushiki Kaisha Image forming apparatus with transfer roller with guide means which adjusts to movements of the roller

Also Published As

Publication number Publication date
JPS4871651A (it) 1973-09-27
DE2263832A1 (de) 1973-07-05
DE2263832B2 (de) 1977-04-28
JPS5136072B2 (it) 1976-10-06
GB1415875A (en) 1975-12-03

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