EP0307022A1 - Transfer foller for electrostatically transferring a developer image and device wich comprises one or more such transfer rollers - Google Patents

Transfer foller for electrostatically transferring a developer image and device wich comprises one or more such transfer rollers Download PDF

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Publication number
EP0307022A1
EP0307022A1 EP88201758A EP88201758A EP0307022A1 EP 0307022 A1 EP0307022 A1 EP 0307022A1 EP 88201758 A EP88201758 A EP 88201758A EP 88201758 A EP88201758 A EP 88201758A EP 0307022 A1 EP0307022 A1 EP 0307022A1
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EP
European Patent Office
Prior art keywords
electrically conducting
transfer roller
transfer
coating
surface layer
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.)
Ceased
Application number
EP88201758A
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German (de)
French (fr)
Inventor
Dick Simons
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.)
Stork Research BV
Original Assignee
Stork Research BV
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 Stork Research BV filed Critical Stork Research BV
Publication of EP0307022A1 publication Critical patent/EP0307022A1/en
Ceased legal-status Critical Current

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    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00Apparatus for electrographic processes using a charge pattern
    • G03G15/14Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
    • G03G15/16Apparatus 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
    • G03G15/1665Apparatus 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
    • G03G15/167Apparatus 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
    • G03G15/1685Structure, details of the transfer member, e.g. chemical composition

Definitions

  • the present invention relates to a transfer roller for electrostatically transferring an image composed of particulate developer which is situated on a first surface to a second surface, comprising a rigid electrically conducting core and a coating composed of resilient material.
  • Such a transfer roller is known, from the Netherlands patent application 7505044 and is used for transferring an image formed from particulate developer (toner) which may be situated, for example, on the surface of an electrophoto­graphic plate to a reception surface.
  • a particle image may be formed by forming in a known manner a latent electrostatic image on the surface of said electrophotographic plate and developing said electrostatic image with a developer which comprises electrically charged particles.
  • a particulate developer may be formed, for example, by an electrically insulating liquid in which charged particles are dispersed; the developer may also be a so-called dry developer in which the continuous phase is composed essentially of air.
  • Transfer of a developer image from the image-carrying surface to a reception surface is carried out by rolling out the reception surface over the surface on which the image is situated with the aid of a suitably electrically energized transfer roller and then peeling off the reception material from the image-carrying surface using the same transfer roller, the transfer roller being connected to a suitable voltage which possesses a polarity which is opposite to the polarity during the rolling-­out operation.
  • the voltages required for such a transfer operation are extremely high because the resilient coating present on the roller in general possesses a very high electrical resistance; in certain cases, voltages in the order of 3000 to 4000 V are required for a good developer transfer.
  • such a transfer roller When it is in use, such a transfer roller has the disadvantage that the required high voltages in many cases give rise to breakdown phenomena both in the vicinity of the roller itself and also in the equipment used for energizing the roller.
  • the consequence of breakdown manifests itself, on the one hand, in poor image transfer results, while, on the other hand, said breakdown phenomena present a fire risk, particularly in those cases in which the developer is a liquid developer having a carrier composed of alkane hydrocarbon (for example, Isopar-g R).
  • the present invention has the object of providing a transfer roller of the type discussed in which, on the one hand, lower electrical voltages can be employed, while, on the other hand, the mechanical characteristics, and in particular the hardness, are adjusted in a manner such that an optimum developer transfer efficiency is achieved in all cases, the deformation of the image being limited to a minimum.
  • the coating is composed of a plastic and possesses a Shore A hardness of 25-55° while constituents for increasing the electrical conductivity of the coating are provided in a continuous electrically conducting surface layer on the coating whereas the material of said surface layer possesses a specific resistance of 1.0 x 10 ⁇ 6 to 1.0 x 10+6 ohm.cm.
  • the transfer roller according to the invention is coated with polyurethane rubber while the Shore A hardness of the coating is approximately 35°.
  • the constituents for increasing the electrical conductivity of the coating in a transfer roller according to the invention are present in a continuous electrically conducting surface layer of the coating of the roller, the material of said surface layer possessing a specific resistance of 1x10 ⁇ 6 to 1x10+6 ohm.cm.
  • the specific resistance of the surface layer is between 1x10 ⁇ 6 and 1x10 ⁇ 2 ohm.cm.
  • the coating possesses per se a Shore A hardness of approximately 35°, while the surface coating is composed of a homogeneous mixture of synthetic resin and an electrically conducting powder.
  • the synthetic resin which forms part of the conducting surface layer is resistant to alkane hydrocarbons
  • the electrically conducting conducting powder may be selected from powders comprising, for example, copper, silver or gold, carbon, electrically conducting oxides, electrically conducting organic compounds etc.
  • the synthetic resin may be a hardened, multi component type such as an epoxy-, polyester- and alkyd-resin or an unhardened type such as polyvinylacetate, polyvinylchloride.
  • the resin-conducting powder layer must be sufficiently flexible, hydro-carbon solvent resistant and durable in use, a skilled worker in this field will know and/or have access to a wide choice in possibilities.
  • an electrically conducting connection may very advantageously be present between the electrically conducting core and the elecrically conducting surface layer of the transfer roller.
  • Such an interconnection has an advantage if developers which are exremely difficult to transfer or developer deposits of high density are employed.
  • connection between the electrically conducting surface layer and the electrically conducting core may be formed in various manners; the connection may have the form of a separate conductor, for example a wire, which is connected, on the one hand, to the spindle of the transfer roller and, on the other hand, is embedded in the electrically conducting surface layer.
  • the connection may also be formed by the interposed flexible coating layer filled with electrically conducting material. In other cases, the connection between the core and the coating layer may also be brought about with the aid of sliding contacts known per se.
  • the electrically conducting surface layer will expediently possess a thickness between 1 and 50 ⁇ m.
  • the invention also relates to a device for transferring, in one or more stages, an image composed of particulate developer on a first surface to another surface, which at least comprises one or more transfer rollers, a frame for mounting said roller or rollers and means for applying electrical voltage to the core of each of the rollers, which is characterised in that at least one of the rollers of the device is formed by a transfer roller such as described above and according to the invention.
  • Figure 1 shows a cross section of a transfer roller according to the invention in a first embodiment
  • figure 2 shows another embodiment of a transfer roller according to the invention.
  • a transfer roller is indicated with reference numeral 1 and comprises an electrically conducting core 2 and a plastic coating layer 3.
  • the coating is provided with constituents 4 for increasing the electrical conductivity of said coating.
  • FIG. 2 is a diagram of another embodiment of the roller from figure 1; the same components are indicated with the same reference numerals.
  • an electrically conducting surface layer 5 is present on the outside of the coating 3; 6 indicates that the surface layer 5 is connected in an electrically conducting manner to the electrically conducting core 2 of the transfer roller.
  • a surface coating layer 5 may be formed, for example, by a mixture of synthetic resin, for example a hardened epoxy resin and a high percentage (higher than 50% by weight) of specially pretreated silver; the conduction layer may also be formed by a synthetic resin which incorporates, for example, graphite to a filling percentage of greater than 50%.
  • synthetic resin for example a hardened epoxy resin and a high percentage (higher than 50% by weight) of specially pretreated silver
  • the conduction layer may also be formed by a synthetic resin which incorporates, for example, graphite to a filling percentage of greater than 50%.
  • the transfer roller according to the invention is particularly suitable for use in all types of devices which have the object of transferring developer images from one surface to another surface; in particular, such rollers are suitable for use in an electrostatically operating multicolour proof printing device such as is described in European Patent 0,082,562 in the name of the Applicant.

Abstract

A transfer roller (1) is disclosed having an electrically conducting core (2), a soft coating (3) of resilient material around said core and a top layer (5) of low specific resistance.
The transfer roller (1) is usable in a process for transferring a toner image from one surface to another, for example from a photoconductor surface to a receptor sheet.
Also is disclosed a device which at least comprises one transfer roller (1) as described.

Description

    Background of the invention:
  • The present invention relates to a transfer roller for electrostatically transferring an image composed of particulate developer which is situated on a first surface to a second surface, comprising a rigid electrically conducting core and a coating composed of resilient material.
  • Such a transfer roller is known, from the Netherlands patent application 7505044 and is used for transferring an image formed from particulate developer (toner) which may be situated, for example, on the surface of an electrophoto­graphic plate to a reception surface. Such a particle image may be formed by forming in a known manner a latent electrostatic image on the surface of said electrophotographic plate and developing said electrostatic image with a developer which comprises electrically charged particles. Depending on the type of developer, either the positions possessing charge or the uncharged sections of the electrophotographic plate are developed in the image. Such a particulate developer may be formed, for example, by an electrically insulating liquid in which charged particles are dispersed; the developer may also be a so-called dry developer in which the continuous phase is composed essentially of air.
  • Transfer of a developer image from the image-carrying surface to a reception surface (for example, a sheet of paper) is carried out by rolling out the reception surface over the surface on which the image is situated with the aid of a suitably electrically energized transfer roller and then peeling off the reception material from the image-carrying surface using the same transfer roller, the transfer roller being connected to a suitable voltage which possesses a polarity which is opposite to the polarity during the rolling-­out operation.
  • The voltages required for such a transfer operation are extremely high because the resilient coating present on the roller in general possesses a very high electrical resistance; in certain cases, voltages in the order of 3000 to 4000 V are required for a good developer transfer.
  • When it is in use, such a transfer roller has the disadvantage that the required high voltages in many cases give rise to breakdown phenomena both in the vicinity of the roller itself and also in the equipment used for energizing the roller. The consequence of breakdown manifests itself, on the one hand, in poor image transfer results, while, on the other hand, said breakdown phenomena present a fire risk, particularly in those cases in which the developer is a liquid developer having a carrier composed of alkane hydrocarbon (for example, Isopar-g R).
  • Another disadvantage of the transfer rollers of the type described and used hitherto is that the developer transfer characteristics of such rollers appear to be strongly dependent on the mechanical characteristics of the material from which the roller coating is formed.
  • Objects of the invention
  • The present invention has the object of providing a transfer roller of the type discussed in which, on the one hand, lower electrical voltages can be employed, while, on the other hand, the mechanical characteristics, and in particular the hardness, are adjusted in a manner such that an optimum developer transfer efficiency is achieved in all cases, the deformation of the image being limited to a minimum.
  • Summary of the invention
  • The abovementioned objects are achieved with the aid of a transfer roller of the type in question and according to the invention in that the coating is composed of a plastic and possesses a Shore A hardness of 25-55° while constituents for increasing the electrical conductivity of the coating are provided in a continuous electrically conducting surface layer on the coating whereas the material of said surface layer possesses a specific resistance of 1.0 x 10⁻⁶ to 1.0 x 10⁺⁶ ohm.cm.
  • As a result of providing the coating of the transfer roller with a Shore A hardness which is between 25 and 55° while, on the other hand, increasing the electrical conductivity of the coating, a very significant improvement in the developer transfer efficienty is achieved, and this couples a minimum image deformation with developer transfer voltages to be used which are reduced to an acceptable level.
  • In an advantageous embodiment of the transfer roller according to the invention, it is coated with polyurethane rubber while the Shore A hardness of the coating is approximately 35°.
  • Using such a roller, the transfer of developer particles is excellent; the image deformation is negligible, while if transfer voltages not exceeding 1000 V are used, a virtually 100% transfer is achieved from an image-carrying surface to, for example, a sheet of paper, for all the normal liquid developers used.
  • In the most advantageous embodiment, the constituents for increasing the electrical conductivity of the coating in a transfer roller according to the invention are present in a continuous electrically conducting surface layer of the coating of the roller, the material of said surface layer possessing a specific resistance of 1x10⁻⁶ to 1x10⁺⁶ ohm.cm. Preferably, the specific resistance of the surface layer is between 1x10⁻⁶ and 1x10⁻² ohm.cm.
  • In particular, in such a roller provided with an electrically conducting surface layer, the coating possesses per se a Shore A hardness of approximately 35°, while the surface coating is composed of a homogeneous mixture of synthetic resin and an electrically conducting powder.
  • Advantageously, the synthetic resin which forms part of the conducting surface layer is resistant to alkane hydrocarbons, while the electrically conducting conducting powder may be selected from powders comprising, for example, copper, silver or gold, carbon, electrically conducting oxides, electrically conducting organic compounds etc.
  • The synthetic resin may be a hardened, multi component type such as an epoxy-, polyester- and alkyd-resin or an unhardened type such as polyvinylacetate, polyvinylchloride.
  • The requirements to make are that the resin-conducting powder layer must be sufficiently flexible, hydro-carbon solvent resistant and durable in use, a skilled worker in this field will know and/or have access to a wide choice in possibilities.
  • To improve the developer transfer efficiency still further, an electrically conducting connection may very advantageously be present between the electrically conducting core and the elecrically conducting surface layer of the transfer roller. Such an interconnection has an advantage if developers which are exremely difficult to transfer or developer deposits of high density are employed.
  • The connection between the electrically conducting surface layer and the electrically conducting core may be formed in various manners; the connection may have the form of a separate conductor, for example a wire, which is connected, on the one hand, to the spindle of the transfer roller and, on the other hand, is embedded in the electrically conducting surface layer. The connection may also be formed by the interposed flexible coating layer filled with electrically conducting material. In other cases, the connection between the core and the coating layer may also be brought about with the aid of sliding contacts known per se.
  • In transfer rollers of the type described above, the electrically conducting surface layer will expediently possess a thickness between 1 and 50 µm.
  • The invention also relates to a device for transferring, in one or more stages, an image composed of particulate developer on a first surface to another surface, which at least comprises one or more transfer rollers, a frame for mounting said roller or rollers and means for applying electrical voltage to the core of each of the rollers, which is characterised in that at least one of the rollers of the device is formed by a transfer roller such as described above and according to the invention.
  • Brief description of the drawings.
  • The invention will now be explained with the aid of the drawing, wherein:
    Figure 1 shows a cross section of a transfer roller according to the invention in a first embodiment, and figure 2 shows another embodiment of a transfer roller according to the invention.
  • In figure 1, a transfer roller is indicated with reference numeral 1 and comprises an electrically conducting core 2 and a plastic coating layer 3. The coating is provided with constituents 4 for increasing the electrical conductivity of said coating.
  • Figure 2 is a diagram of another embodiment of the roller from figure 1; the same components are indicated with the same reference numerals. In this case, an electrically conducting surface layer 5 is present on the outside of the coating 3; 6 indicates that the surface layer 5 is connected in an electrically conducting manner to the electrically conducting core 2 of the transfer roller. Such a surface coating layer 5 may be formed, for example, by a mixture of synthetic resin, for example a hardened epoxy resin and a high percentage (higher than 50% by weight) of specially pretreated silver; the conduction layer may also be formed by a synthetic resin which incorporates, for example, graphite to a filling percentage of greater than 50%. Many possibilities are available and are known to the person skilled in the art for forming the electrically conducting surface layer 5; these will not be discusses further.
  • The transfer roller according to the invention is particularly suitable for use in all types of devices which have the object of transferring developer images from one surface to another surface; in particular, such rollers are suitable for use in an electrostatically operating multicolour proof printing device such as is described in European Patent 0,082,562 in the name of the Applicant.

Claims (7)

1. Transfer roller for electrostatically transferring an image composed of particulate developer which is situated on a first surface to a second surface, comprising a rigid electrically conducting core and a coating composed of resilient material characterized in that the coating possesses a Shore A hardness of 25-55° and that constituents for increasing the electrical conductivity of the coating are provided in a continuous electrically conducting surface layer (5) on the coating (3) and the material of said surface layer possesses a specific resistance of 1.0x10⁻⁶ - 1x10⁺⁶ ohm.cm.
2. Transfer roller according to claim 1, characterized in that the surface layer possesses a specific resistance between 1.0x10⁻⁶ and 1.0x10⁻² ohm.cm.
3. Transfer roller according to claim 1-2, characterized in that the coating (3) possesses a Shore A hardness of approximately 35° and possesses a surface layer (5) which is composed of a homogeneous mixture of synthethic resin and an electrically conducting powder.
4. Transfer roller according to claim 3, characterized in that the synthetic resin is cured if necessary and resistant to alkane hydrocarbons and is filled with electrically conducting material selected from powders of metals such as copper, silver, gold etc., carbon, such as graphite, electrically conducting oxides, electrically conducting organic compounds etc.
5. Transfer roller according to claim 1-4, characterized in that an electrically conducting connection (6) is present between the electrically conducting surface layer (5) and the core (2) of the transfer roller (1).
6. Transfer roller according to claim 1-5, characterized in that the electrically conducting surface layer (5) possesses a thickness between 1 and 50 µm.
7. Device for transferring, in one or more stages, an image composed of particulate developer on a first surface to another surface, which at least comprises one or more transfer rollers, a frame for mounting said roller or rollers and means for applying electrical voltage to the core of each of the rollers, characterized in that at least one of the transfer rollers is formed by a transfer roller according to one or more of claims 1-6.
EP88201758A 1987-08-25 1988-08-15 Transfer foller for electrostatically transferring a developer image and device wich comprises one or more such transfer rollers Ceased EP0307022A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8701989A NL8701989A (en) 1987-08-25 1987-08-25 TRANSFER ROLLERS FOR ELECTROSTATIC TRANSFER OF A DEVELOPER IMAGE AND DEVICE INCLUDING ONE OR MORE OF SUCH TRANSFER ROLLERS.
NL8701989 1987-08-25

Publications (1)

Publication Number Publication Date
EP0307022A1 true EP0307022A1 (en) 1989-03-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP88201758A Ceased EP0307022A1 (en) 1987-08-25 1988-08-15 Transfer foller for electrostatically transferring a developer image and device wich comprises one or more such transfer rollers

Country Status (5)

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EP (1) EP0307022A1 (en)
JP (1) JPH01113778A (en)
AU (1) AU591604B2 (en)
DK (1) DK472288A (en)
NL (1) NL8701989A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0399186A2 (en) * 1989-04-04 1990-11-28 Seiko Epson Corporation Wet type image forming apparatus
EP0400572A2 (en) * 1989-05-31 1990-12-05 Kabushiki Kaisha Toshiba Recording apparatus
WO1993006533A1 (en) * 1991-09-23 1993-04-01 Eastman Kodak Company Method and apparatus of forming a toner image on a receiving sheet using an intermediate image member

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2559306A1 (en) * 2004-03-15 2005-09-22 Zip Industries (Aust) Pty Ltd A water heater and a method of operating same

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3627523A (en) * 1968-03-14 1971-12-14 Addressograph Multigraph Multiple powder transfer in photoelectrostatic duplicator
US3924943A (en) * 1974-06-11 1975-12-09 Xerox Corp Segmented biased transfer member
US3959574A (en) * 1974-04-26 1976-05-25 Xerox Corporation Biasable member and method for making
US4062812A (en) * 1976-07-01 1977-12-13 Xerox Corporation Method for extending the functional life of polymers used in xerographic devices
US4063808A (en) * 1976-03-23 1977-12-20 International Business Machines Corporation Apparatus for neutralizing toner in a no charge exchange transfer
US4302093A (en) * 1979-10-17 1981-11-24 Savin Corporation Combined transfer and registration system for electrophotographic copier

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1071466A (en) * 1976-07-21 1980-02-12 Research Laboratories Of Australia Pty. Limited Method of and means for the production of lithographic printing plates
JPS54156548A (en) * 1978-05-30 1979-12-10 Ricoh Co Ltd Roller for electrophotographic copier

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3627523A (en) * 1968-03-14 1971-12-14 Addressograph Multigraph Multiple powder transfer in photoelectrostatic duplicator
US3959574A (en) * 1974-04-26 1976-05-25 Xerox Corporation Biasable member and method for making
US3924943A (en) * 1974-06-11 1975-12-09 Xerox Corp Segmented biased transfer member
US4063808A (en) * 1976-03-23 1977-12-20 International Business Machines Corporation Apparatus for neutralizing toner in a no charge exchange transfer
US4062812A (en) * 1976-07-01 1977-12-13 Xerox Corporation Method for extending the functional life of polymers used in xerographic devices
US4302093A (en) * 1979-10-17 1981-11-24 Savin Corporation Combined transfer and registration system for electrophotographic copier

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 7, no. 164 (P-211)[1309], 19th July 1983; & JP-A-58 72 177 (OLYMPUS KOGAKU KOGYO K.K.) 30-04-1983 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0399186A2 (en) * 1989-04-04 1990-11-28 Seiko Epson Corporation Wet type image forming apparatus
EP0399186B1 (en) * 1989-04-04 1994-11-30 Seiko Epson Corporation Wet type image forming apparatus
EP0400572A2 (en) * 1989-05-31 1990-12-05 Kabushiki Kaisha Toshiba Recording apparatus
EP0400572A3 (en) * 1989-05-31 1992-05-06 Kabushiki Kaisha Toshiba Recording apparatus
WO1993006533A1 (en) * 1991-09-23 1993-04-01 Eastman Kodak Company Method and apparatus of forming a toner image on a receiving sheet using an intermediate image member

Also Published As

Publication number Publication date
AU591604B2 (en) 1989-12-07
JPH01113778A (en) 1989-05-02
AU2068088A (en) 1989-03-02
DK472288A (en) 1989-02-26
NL8701989A (en) 1989-03-16
DK472288D0 (en) 1988-08-24

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