WO2023039304A1 - Photoconductor spaced apart from transfer device to form gap therebetween - Google Patents

Photoconductor spaced apart from transfer device to form gap therebetween Download PDF

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Publication number
WO2023039304A1
WO2023039304A1 PCT/US2022/071926 US2022071926W WO2023039304A1 WO 2023039304 A1 WO2023039304 A1 WO 2023039304A1 US 2022071926 W US2022071926 W US 2022071926W WO 2023039304 A1 WO2023039304 A1 WO 2023039304A1
Authority
WO
WIPO (PCT)
Prior art keywords
image
photoconductor
forming apparatus
transfer
transfer roller
Prior art date
Application number
PCT/US2022/071926
Other languages
French (fr)
Inventor
Takayuki Wakai
Original Assignee
Hewlett-Packard Development Company, L.P.
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 Hewlett-Packard Development Company, L.P. filed Critical Hewlett-Packard Development Company, L.P.
Publication of WO2023039304A1 publication Critical patent/WO2023039304A1/en

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/14—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
    • G03G15/1665—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 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
    • G03G15/167—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 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
    • 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
    • G03G15/1665—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 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
    • G03G15/167—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 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
    • G03G15/1675—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 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 with means for controlling the bias applied in the transfer nip
    • 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
    • G03G15/1665—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 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
    • G03G15/167—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 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
    • G03G15/1685—Structure, details of the transfer member, e.g. chemical composition
    • 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
    • G03G15/6588—Apparatus which relate to the handling of copy material characterised by the copy material, e.g. postcards, large copies, multi-layered materials, coloured sheet material
    • G03G15/6594—Apparatus which relate to the handling of copy material characterised by the copy material, e.g. postcards, large copies, multi-layered materials, coloured sheet material characterised by the format or the thickness, e.g. endless forms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
    • G03G21/06—Eliminating residual charges from a reusable imaging member
    • G03G21/08—Eliminating residual charges from a reusable imaging member using optical radiation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00443—Copy medium
    • G03G2215/00451—Paper
    • G03G2215/00476—Non-standard property
    • G03G2215/00481—Thick
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00443—Copy medium
    • G03G2215/00451—Paper
    • G03G2215/00476—Non-standard property
    • G03G2215/00485—Thin
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00535—Stable handling of copy medium
    • G03G2215/00717—Detection of physical properties
    • G03G2215/00738—Detection of physical properties of sheet thickness or rigidity
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2221/00—Processes not provided for by group G03G2215/00, e.g. cleaning or residual charge elimination
    • G03G2221/16—Mechanical means for facilitating the maintenance of the apparatus, e.g. modular arrangements and complete machine concepts
    • G03G2221/1651—Mechanical means for facilitating the maintenance of the apparatus, e.g. modular arrangements and complete machine concepts for connecting the different parts
    • G03G2221/1654—Locks and means for positioning or alignment

Definitions

  • the transfer device causes the toner image formed on the image-forming surface to be transferred to the print medium that is conveyed to a transfer region located between the transfer device and the photoconductor.
  • FIG. 1 is a schematic view of an example image forming apparatus.
  • FIG. 2 is a schematic diagram illustrating the vicinity of an example photoconductor and an example transfer device.
  • FIG. 3 is a schematic partial view of the example photoconductor and of an example transfer device.
  • FIG. 4 is a schematic partial view of the example photoconductor and of an example transfer device.
  • FIG. 5 is a schematic partial view of the example photoconductor and of an example transfer device.
  • FIG. 6 is a schematic partial view of the example photoconductor and of an example transfer device.
  • FIG. 7 is a partial cross-sectional view of an example transfer roller.
  • FIG. 8 is a graph showing a state change over time during a printing end process.
  • FIG. 9 is a table showing example experimental results of a charging state of a photoconductor drum when the printing end process is performed.
  • An example image forming apparatus includes a photoconductor which has an image-forming surface that forms a toner image thereon and a transfer device which is located adjacent to the photoconductor to transfer the toner image to a print medium at a transfer region located between the photoconductor and the transfer device.
  • the transfer device is spaced apart from the image-forming surface to form a gap at the transfer region. Accordingly, for example, when a voltage is applied to the transfer device for cleaning, the influence of the voltage on the photoconductor can be suppressed.
  • FIG. 1 is a schematic view showing an example image forming apparatus 1.
  • the image forming apparatus 1 includes a cartridge compartment 20, a photoconductor 30, an exposure device 40, a developing device 50, a transfer device 60, a cleaning device 70, a fixing device 80, a discharge device 90, and a control unit (or controller) 100.
  • the image forming apparatus 1 includes a discharge path 7.
  • the image forming apparatus 1 forms an image on a sheet (e.g., a paper sheet) 5 which is a recording medium conveyed in the discharge path 7.
  • the sheet 5 is accommodated in a cassette 3 in a stacked state, as part of a stack of sheets.
  • the sheet 5 is picked up by a pickup roller 11 and is conveyed in the discharge path 7.
  • the sheet 5 conveyed in the discharge path 7 is separated from the stacked as a single sheet, for example, by a separation roller 12.
  • the single sheet 5 is conveyed to a transfer region 8 which will be described below, at a predetermined timing by a resist roller 13.
  • a toner cartridge 2 is accommodated in the cartridge compartment 20.
  • the example toner cartridge 2 has a substantially cylindrical shape.
  • the cartridge compartment 20 may have a cylindrical shape.
  • the cartridge compartment 20 has a substantially cylindrical shape extending in a longitudinal direction in the Y direction.
  • the photoconductor 30 has an image-forming surface to form a toner image.
  • the example photoconductor 30 includes a photoconductor drum 31 having an image-forming surface formed on an outer peripheral surface.
  • the photoconductor drum 31 has, for example, a substantially cylindrical shape extending in the Y direction.
  • An electrostatic latent image is formed on the outer peripheral surface of the photoconductor drum 31 .
  • a charging roller 32 is disposed to face the outer peripheral surface of the photoconductor drum 31 .
  • the charging roller 32 charges the outer peripheral surface of the photoconductor drum 31 to a predetermined potential.
  • the charging roller 32 may rotate to follow the rotation of the photoconductor drum 31 .
  • the exposure device 40 directs a light to the outer peripheral surface (the image-forming surface) of the photoconductor drum 31 having been previously charged by the charging roller 32, in response to an image to be formed on the sheet 5.
  • a potential of a portion exposed by the exposure device 40 in the outer peripheral surface of the photoconductor drum 31 changes to form an electrostatic latent image on the outer peripheral surface of the photoconductor drum 31 .
  • the example exposure device 40 directs a laser beam to the outer peripheral surface of the photoconductor drum 31 , that is output from a laser beam source by reflecting the laser beam with a polygon mirror. Further, the exposure device 40 can remove static electricity on the image-forming surface by exposing the image-forming surface of the photoconductor drum 31 .
  • the developing device 50 develops the electrostatic latent image formed on the outer peripheral surface of the photoconductor drum 31 by the toner supplied from the toner cartridge 2 to form a toner image on the outer peripheral surface of the photoconductor drum 31.
  • the developing device 50 may include a developing roller 52, a supply auger 54, and a stirring auger 56.
  • the developing roller 52, the supply auger 54, and the stirring auger 56 are accommodated in a housing 51.
  • the stirring auger 56 conveys a developer in the axial direction (for example, the Y direction) of the stirring auger 56 while stirring the developer in a conveyance path 51 a.
  • the developer conveyed to one end of the stirring auger 56 in the axial direction enters a conveyance path 51 b which is adjacent to the conveyance path 51 a.
  • the supply auger 54 conveys the developer in the conveyance path 51 b in the axial direction (for example, the Y direction) of the supply auger 54.
  • the developer conveyed in the conveyance path 51 b is picked up by the developing roller 52.
  • the picked-up developer is formed on the developing roller 52 as a layer having a predetermined thickness by a layer thickness regulating member 58 and is carried on the developing roller 52 while being formed in the layered shape.
  • the toner in the carried developer is transferred to the electrostatic latent image of the photoconductor drum 31 in order to develop the electrostatic latent image.
  • the transfer device 60 is located adjacent to the photoconductor 30.
  • the transfer device 60 transfers a toner image to the sheet 5 conveyed through the transfer region 8 (cf. FIG. 2) located between the photoconductor 30 and the transfer device 60.
  • the example transfer device 60 includes a transfer roller 62.
  • the transfer roller 62 has, for example, an axis extending in parallel to the axis of the photoconductor drum 31 .
  • the transfer region 8 (transfer nip region) is formed between the outer peripheral surface of the transfer roller 62 and the outer peripheral surface of the photoconductor drum 31 .
  • the transfer roller 62 applies an electric charge (transfer electric charge) to the sheet 5 conveyed to the transfer region 8 so that the toner image formed on the outer peripheral surface of the photoconductor drum 31 is transferred to the sheet 5.
  • the toner image is transferred to the sheet 5 is conveyed to the transfer region 8 by the transfer roller 62.
  • the cleaning device 70 collects residual toner (untransferred toner) remaining on the photoconductor drum 31 after the toner image formed on the photoconductor drum 31 has been transferred to the sheet 5.
  • the cleaning device 70 includes, for example, a blade 71 and a recovery auger 73.
  • the recovery auger 73 is accommodated in a conveyance path 76 formed in a housing 75 of the cleaning device 70.
  • the cleaning device 70 removes the toner from the photoconductor drum 31 and collects the toner in such a manner that the blade 71 scrapes off the toner remaining on the outer peripheral surface of the photoconductor drum 31 .
  • the blade 71 is fixed to the housing 75 to be in contact with the outer peripheral surface of the photoconductor drum 31 .
  • the recovery auger 73 has an axis extending in the Y direction.
  • the recovery auger 73 rotates around the axis so that the toner stored in the housing 75 is conveyed in the axial direction (the Y direction) in which the axis extends.
  • the conveyed toner may be stored in a waste toner collection container.
  • the fixing device 80 fixes the toner image to the sheet 5 by passing the sheet 5 through a fixing nip region for heating and pressing the sheet.
  • the fixing device 80 includes a heating roller 82 which heats the sheet 5 and a pressing roller 84 which is pressed against the heating roller 82 and rotationally drives the heating roller.
  • the fixing nip region of the fixing device 80 is formed between the heating roller 82 and the pressing roller 84.
  • the discharge device 90 includes, for example, a discharge roller 92 and a discharge roller 94 which discharge the sheet 5 to which the toner image has been fixed, to the outside of the image forming apparatus 1 .
  • the control unit (or controller) 100 controls the operation of the image forming apparatus 1 to operate the image forming apparatus 1 .
  • the example control unit 100 may include, for example, an electronic control unit including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.
  • FIG. 2 is a schematic view showing a configuration in the vicinity of the example photoconductor 30 and of the example transfer device 60.
  • an image-forming surface 31 a is formed on the outer peripheral surface of the photoconductor drum 31 .
  • the transfer device 60 is spaced apart from the image-forming surface 31 a of the photoconductor drum 31 to form a gap 9 in the transfer region 8.
  • the image-forming surface 31 a of the photoconductor drum 31 and an outer peripheral surface 62a of the transfer roller 62 of the transfer device 60 are spaced apart so as to not be in contact with each other.
  • the width of the gap 9 can be the closest distance between the image-forming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62 of the transfer device 60.
  • the gap 9 formed in the transfer region 8 is greater than 0 mm. Accordingly, the transfer device 60 can form the gap 9 which prevents an electrical contact between the image-forming surface 31a of the photoconductor drum 31 and the transfer device 60.
  • the image forming apparatus 1 is set in advance to print (process) the sheet 5 having a thickness in a predetermined thickness range.
  • the example control unit (or controller) 100 includes a storage unit (or storage device) 102.
  • the predetermined thickness range of the sheet 5 to be printed by the image forming apparatus 1 is stored in the storage unit 102 in advance.
  • the gap 9 in the transfer region 8 is equal to or less than the minimum thickness of the predetermined thickness range of the sheet 5 to be printed by the image forming apparatus 1 .
  • the example image forming apparatus 1 can print a thin sheet (for example, having a thickness of 0.06 mm) as a sheet having a predetermined minimum thickness.
  • the size or width of the gap 9 which is the closest distance between the photoconductor drum 31 and the transfer roller 62 may be equal to or less than 0.06 mm as an example. Further, the size or width of the gap 9 which is the closest distance between the photoconductor drum 31 and the transfer roller 62 may be equal to or greater than 0.01 mm as an example.
  • the sheet 5 is brought into contact with both the transfer device 60 and the photoconductor
  • the example transfer device 60 includes a spacer 64 (cf. FIG. 3) which forms the gap 9 in addition to the above-described transfer roller 62.
  • a spacer 64 cf. FIG. 3 which forms the gap 9 in addition to the above-described transfer roller 62.
  • various examples of the example spacer 64 forming the gap 9 will be described.
  • an example of the spacer 64 may include a pair of band-shaped members 65 respectively wound on the outer peripheral surfaces 62a at the two opposite ends of the transfer roller 62. Additionally, in FIG. 3, although the band-shaped member 65 provided at a first end portion of the transfer roller 62 is shown, the band-shaped member 65 is also provided at the second end portion of the transfer roller 62. The same applies to FIGS. 4 to 6 described below.
  • the outer peripheral surface of the band-shaped member 65 may contact a portion provided with the imageforming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 . Accordingly, the outer peripheral surface 62a of the transfer roller 62 does not contact the image-forming surface 31a of the photoconductor drum 31. In this way, the band-shaped member 65 that is wound on the transfer roller 62 forms the gap 9 between the image-forming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62. Since the band-shaped member 65 contacts the photoconductor drum 31 , the transfer roller 62 may rotate to follow the rotation of the photoconductor drum 31 .
  • the pair of band-shaped members 65 may have an adhesive layer on the surface facing the outer peripheral surface 62a of the transfer roller 62. In this case, the band-shaped member 65 may adhere to the outer peripheral surface 62a of the transfer roller 62. Accordingly, the band-shaped member 65 can be easily attached to the outer peripheral surface 62a of the transfer roller 62.
  • each of the pair of band-shaped members 65 may be wound around the outer peripheral surface 62a of the transfer roller 62 by two or more turns. Accordingly, the size of the gap 9 can be easily adjusted by adjusting the number of times of winding the band-shaped member 65.
  • an example of the spacer 64 may include a pair of rings 66 respectively attached to the outer peripheral surfaces 62a at opposite ends of the transfer roller 62.
  • the outer peripheral surfaces of the pair of rings 66 contact the photoconductor drum 31 .
  • the outer peripheral surface of the ring 66 contacts the outer peripheral surface 31 b of the photoconductor drum 31 .
  • the outer peripheral surface of the ring 66 may contact a portion provided with the image-forming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 .
  • the ring 66 has an annular shape, and the transfer roller 62 extends through the ring 66.
  • the transfer roller 62 may rotate to follow the rotation of the photoconductor drum 31 .
  • an example of the spacer 64 may include a pair of caps 67 respectively covering the two opposite end portions of the transfer roller 62.
  • Each cap 67 includes an annular ring portion (ring) 67a attached to the corresponding one of the outer peripheral surfaces 62a of the two opposite ends of the transfer roller 62, and a plate portion 67b covering the end surface of the transfer roller 62.
  • the outer peripheral surface of the ring portion 67a contacts the photoconductor drum 31 . Namely, the outer peripheral surface of the ring portion 67a contacts the outer peripheral surface 31 b of the photoconductor drum 31 .
  • the outer peripheral surface of the ring portion 67a may contact a portion provided with the image-forming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 .
  • the transfer roller 62 extends through the ring portion 67a of the cap 67. [0030] Also in this case, it is possible to easily form the gap 9 between the image-forming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62. Further, the size of the gap 9 in the circumferential direction of the transfer roller 62 does not change by using the cap 67 with the ring portion 67a having a seamless annular shape. Since the ring portion 67a of the cap 67 contacts the photoconductor drum 31 , the transfer roller 62 may rotate to follow the rotation of the photoconductor drum 31.
  • an example of the spacer 64 may include a pair of disks 68 respectively attached the opposite ends of a rotating shaft 63 of the transfer roller 62.
  • the disk 68 is attached to the rotating shaft 63 in such a manner that the rotating shaft 63 extends through the center portion of the disk 68.
  • the diameter of the disk 68 is greater than the diameter of the transfer roller 62.
  • the outer peripheral surfaces of the pair of disks 68 contact the photoconductor drum 31. Namely, the outer peripheral surface of the disk 68 contacts the outer peripheral surface 31 b of the photoconductor drum 31 . Further, the outer peripheral surface of the disk 68 may contact a portion provided with the image-forming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 .
  • a resistance layer 87 is provided on the outer peripheral surface of the example transfer roller 62.
  • the transfer roller 62 includes a metal tube 86 disposed outside the rotating shaft 63 and the resistance layer 87.
  • the metal tube 86 has a substantially cylindrical shape.
  • the rotating shaft 63 is disposed inside the metal tube 86.
  • an intermediate member 88 may be provided to fill the gap between the metal tube 86 and the rotating shaft 63.
  • the metal tube 86 may function as the rotating shaft 63. Namely, the metal tube 86 and the rotating shaft 63 may be integrated into a single component.
  • the resistance layer 87 is provided on the outer peripheral surface of the metal tube 86.
  • the resistance layer 87 is formed of, for example, resin, rubber, or the like. This rubber may have, for example, an insulator whose resistance value has been adjusted with a conductive agent or the like.
  • the layer thickness of the example resistance layer 87 is equal to or greater than 10 pm and equal to or less than 100 pm. Further, the resistance value of the example resistance layer 87 is equal to or greater than 5 logQ and equal to or less than 10 logQ.
  • a standard transfer roller which is accommodated in the image forming apparatus to contact the photoconductor drum may be used as the transfer roller 62.
  • the example image forming apparatus 1 performs a printing end process after the printing on the sheet 5 ends.
  • the voltage applied to the photoconductor 30 and to the transfer device 60 in the printing end process will be described.
  • static elimination is performed on the image-forming surface 31a of the photoconductor drum 31 .
  • a positive voltage and a negative voltage are alternately applied to the transfer roller 62 for cleaning the transfer roller 62. Accordingly, the toner attached to the transfer roller 62 is released from the transfer roller 62 to be removed from the transfer roller 62.
  • the control unit 100 includes a voltage control unit (or voltage control device) 101.
  • the voltage control unit 101 controls a voltage applied to the photoconductor drum 31 and the like.
  • FIG. 8 shows a state in which the printing end process starts at the time t1 .
  • the surface potential of the photoconductor drum 31 (the potential of the image-forming surface 31 a) is in a negatively charged state as a voltage level for performing printing in such a manner that the photoconductor drum is charged by the charging roller 32.
  • the exposure device 40 is in an off state.
  • a positive voltage is applied to the transfer roller 62 as a voltage level for performing printing.
  • a negative voltage is applied to each of the charging roller 32 and the developing device 50 as a voltage level for performing printing.
  • the control unit 100 starts a printing end process.
  • the voltage control unit 101 stops the application of the positive voltage to the transfer roller 62 at the time t1 .
  • the voltage control unit 101 stops the application of the negative voltage to the charging roller 32 at the time t2 and stops the application of the negative voltage to the developing device 50 at the time t3. Since the application of the negative voltage to the charging roller 32 is stopped at the time t2, the surface potential of the photoconductor drum 31 changes after the time t2, to reach 0 V.
  • the control unit 100 operates the exposure device 40 to expose the image-forming surface 31 a of the photoconductor drum 31 and eliminates static electricity of the image-forming surface 31a. Accordingly, the surface potential of the photoconductor drum 31 is 0 V after the time t4. After static elimination of the photoconductor drum 31 , the control unit 100 stops the exposure device 40 at the time t5.
  • the voltage control unit 101 After static elimination of the image-forming surface 31 a of the photoconductor drum 31 is performed by the exposure device 40, the voltage control unit 101 alternately applies a positive voltage and a negative voltage to the transfer roller 62 after the time t6.
  • the gap 9 is provided between the photoconductor drum 31 and the transfer roller 62. Accordingly, the photoconductor drum 31 is not charged even when a positive voltage and a negative voltage are alternately applied to the transfer roller 62. Therefore, as shown in FIG. 8, the surface potential of the photoconductor drum 31 is 0
  • the toner or carrier may be drawn to the charged photoconductor drum. Accordingly, when the photoconductor drum 31 is not charged as described above, the transfer of toner and carrier from the developing device 50 to the photoconductor drum 31 is prevented or suppressed.
  • the control unit 100 ends the printing end process at the time t8.
  • FIG. 9 shows the presence or absence of charging (surface charging) of the photoconductor drum 31 when a positive voltage is applied to the transfer roller 62, the presence or absence of charging (surface charging) of the photoconductor drum 31 when a negative voltage is applied to the transfer roller 62, the presence or absence of transfer failure of the toner image on the sheet 5, and the presence or absence of conveyance failure of the sheet 5.
  • a minimum thickness of the predetermined thickness range of the sheet 5 to be printed is set to 0.06 mm. Therefore, in the example image forming apparatus 1 , the gap 9 having a size greater than 0 mm and equal to or less than 0.06 mm is set as the gap 9 between the photoconductor drum 31 and the transfer roller 62. Here, an experiment was performed when the size of the gap 9 was 0.03 mm and 0.06 mm.
  • the transfer device 60 is provided to form the gap 9 in the transfer region 8 between the image-forming surface 31 a of the photoconductor 30 and the transfer device. Further, the gap 9 in the transfer region 8 is equal to or less than the minimum thickness of the predetermined thickness range of the sheet 5 to be printed.
  • the transfer device 60 it is possible to prevent or suppress the photoconductor drum 31 from being charged even when a voltage is applied to the transfer roller 62 during the printing end process. Accordingly, in the example image forming apparatus 1 , it is possible to prevent or suppress the toner or carrier from transferring to the photoconductor drum 31 by preventing the photoconductor drum 31 from being charged.
  • the gap 9 is provided between the photoconductor drum 31 and the transfer roller 62, it is possible to prevent or suppress the toner from moving and adhering to the transfer roller 62 from the photoconductor drum 31 and to prevent or suppress the carrier from sticking to the photoconductor drum 31 (Dimple).
  • the maximum value of the size of the gap 9 is the minimum thickness of the predetermined thickness range of the sheet 5 to be printed.
  • the image forming apparatus 1 can prevent the photoconductor drum 31 from being charged during the printing end process while preventing or suppressing a transfer failure of the toner image to the sheet 5 and a conveyance failure of the sheet 5 during the printing operation of the sheet 5.
  • the example image forming apparatus 1 removes static electricity from the photoconductor drum 31 by exposing the photoconductor drum with the exposure device 40 during the printing end process. Accordingly, the image forming apparatus 1 does not need to include a static elimination device for performing static elimination on the photoconductor drum 31 in addition to the exposure device 40.

Abstract

An image forming apparatus includes a photoconductor which has an image-forming surface to form a toner image, and a transfer device located adjacent to the photoconductor to transfer the toner image to a print medium conveyed through a transfer region located between the photoconductor and the transfer device. The transfer device is spaced apart from the image-forming surface of the photoconductor to form a gap at the transfer region. The image forming apparatus is set to process print media having thicknesses within a predetermined thickness range. The gap at the transfer region is equal to or less than a minimum thickness of the predetermined thickness range.

Description

PHOTOCONDUCTOR SPACED APART FROM TRANSFER DEVICE TO FORM GAP THEREBETWEEN
BACKGROUND
[0001] An image forming apparatus which forms an image on a print medium includes a photoconductor which has an image-forming surface forming a toner image thereon and a transfer device which transfers the toner image to the print medium. The transfer device causes the toner image formed on the image-forming surface to be transferred to the print medium that is conveyed to a transfer region located between the transfer device and the photoconductor.
BRIEF DESCRIPTION OF DRAWINGS
[0002] FIG. 1 is a schematic view of an example image forming apparatus.
FIG. 2 is a schematic diagram illustrating the vicinity of an example photoconductor and an example transfer device.
FIG. 3 is a schematic partial view of the example photoconductor and of an example transfer device.
FIG. 4 is a schematic partial view of the example photoconductor and of an example transfer device.
FIG. 5 is a schematic partial view of the example photoconductor and of an example transfer device.
FIG. 6 is a schematic partial view of the example photoconductor and of an example transfer device.
FIG. 7 is a partial cross-sectional view of an example transfer roller.
FIG. 8 is a graph showing a state change over time during a printing end process. FIG. 9 is a table showing example experimental results of a charging state of a photoconductor drum when the printing end process is performed.
DETAILED DESCRIPTION
[0003] In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted. [0004] An example image forming apparatus includes a photoconductor which has an image-forming surface that forms a toner image thereon and a transfer device which is located adjacent to the photoconductor to transfer the toner image to a print medium at a transfer region located between the photoconductor and the transfer device. The transfer device is spaced apart from the image-forming surface to form a gap at the transfer region. Accordingly, for example, when a voltage is applied to the transfer device for cleaning, the influence of the voltage on the photoconductor can be suppressed.
[0005] FIG. 1 is a schematic view showing an example image forming apparatus 1. The image forming apparatus 1 includes a cartridge compartment 20, a photoconductor 30, an exposure device 40, a developing device 50, a transfer device 60, a cleaning device 70, a fixing device 80, a discharge device 90, and a control unit (or controller) 100. The image forming apparatus 1 includes a discharge path 7. The image forming apparatus 1 forms an image on a sheet (e.g., a paper sheet) 5 which is a recording medium conveyed in the discharge path 7.
[0006] According to examples, the sheet 5 is accommodated in a cassette 3 in a stacked state, as part of a stack of sheets. The sheet 5 is picked up by a pickup roller 11 and is conveyed in the discharge path 7. The sheet 5 conveyed in the discharge path 7 is separated from the stacked as a single sheet, for example, by a separation roller 12. The single sheet 5 is conveyed to a transfer region 8 which will be described below, at a predetermined timing by a resist roller 13.
[0007] According to examples, a toner cartridge 2 is accommodated in the cartridge compartment 20. The example toner cartridge 2 has a substantially cylindrical shape. The cartridge compartment 20 may have a cylindrical shape. In the example of FIG. 1 , the cartridge compartment 20 has a substantially cylindrical shape extending in a longitudinal direction in the Y direction.
[0008] The photoconductor 30 has an image-forming surface to form a toner image. The example photoconductor 30 includes a photoconductor drum 31 having an image-forming surface formed on an outer peripheral surface. The photoconductor drum 31 has, for example, a substantially cylindrical shape extending in the Y direction. An electrostatic latent image is formed on the outer peripheral surface of the photoconductor drum 31 . A charging roller 32 is disposed to face the outer peripheral surface of the photoconductor drum 31 . The charging roller 32 charges the outer peripheral surface of the photoconductor drum 31 to a predetermined potential. The charging roller 32 may rotate to follow the rotation of the photoconductor drum 31 .
[0009] The exposure device 40 directs a light to the outer peripheral surface (the image-forming surface) of the photoconductor drum 31 having been previously charged by the charging roller 32, in response to an image to be formed on the sheet 5. A potential of a portion exposed by the exposure device 40 in the outer peripheral surface of the photoconductor drum 31 changes to form an electrostatic latent image on the outer peripheral surface of the photoconductor drum 31 . The example exposure device 40 directs a laser beam to the outer peripheral surface of the photoconductor drum 31 , that is output from a laser beam source by reflecting the laser beam with a polygon mirror. Further, the exposure device 40 can remove static electricity on the image-forming surface by exposing the image-forming surface of the photoconductor drum 31 .
[0010] The developing device 50 develops the electrostatic latent image formed on the outer peripheral surface of the photoconductor drum 31 by the toner supplied from the toner cartridge 2 to form a toner image on the outer peripheral surface of the photoconductor drum 31. In some examples, the developing device 50 may include a developing roller 52, a supply auger 54, and a stirring auger 56.
[0011 ] The developing roller 52, the supply auger 54, and the stirring auger 56 are accommodated in a housing 51. The stirring auger 56 conveys a developer in the axial direction (for example, the Y direction) of the stirring auger 56 while stirring the developer in a conveyance path 51 a. The developer conveyed to one end of the stirring auger 56 in the axial direction enters a conveyance path 51 b which is adjacent to the conveyance path 51 a. The supply auger 54 conveys the developer in the conveyance path 51 b in the axial direction (for example, the Y direction) of the supply auger 54. The developer conveyed in the conveyance path 51 b is picked up by the developing roller 52. The picked-up developer is formed on the developing roller 52 as a layer having a predetermined thickness by a layer thickness regulating member 58 and is carried on the developing roller 52 while being formed in the layered shape. The toner in the carried developer is transferred to the electrostatic latent image of the photoconductor drum 31 in order to develop the electrostatic latent image.
[0012] The transfer device 60 is located adjacent to the photoconductor 30. The transfer device 60 transfers a toner image to the sheet 5 conveyed through the transfer region 8 (cf. FIG. 2) located between the photoconductor 30 and the transfer device 60. The example transfer device 60 includes a transfer roller 62. The transfer roller 62 has, for example, an axis extending in parallel to the axis of the photoconductor drum 31 . The transfer region 8 (transfer nip region) is formed between the outer peripheral surface of the transfer roller 62 and the outer peripheral surface of the photoconductor drum 31 . The transfer roller 62 applies an electric charge (transfer electric charge) to the sheet 5 conveyed to the transfer region 8 so that the toner image formed on the outer peripheral surface of the photoconductor drum 31 is transferred to the sheet 5. The toner image is transferred to the sheet 5 is conveyed to the transfer region 8 by the transfer roller 62.
[0013] The cleaning device 70 collects residual toner (untransferred toner) remaining on the photoconductor drum 31 after the toner image formed on the photoconductor drum 31 has been transferred to the sheet 5. The cleaning device 70 includes, for example, a blade 71 and a recovery auger 73. As an example, the recovery auger 73 is accommodated in a conveyance path 76 formed in a housing 75 of the cleaning device 70. The cleaning device 70 removes the toner from the photoconductor drum 31 and collects the toner in such a manner that the blade 71 scrapes off the toner remaining on the outer peripheral surface of the photoconductor drum 31 . The blade 71 is fixed to the housing 75 to be in contact with the outer peripheral surface of the photoconductor drum 31 . [0014] The recovery auger 73 has an axis extending in the Y direction. The recovery auger 73 rotates around the axis so that the toner stored in the housing 75 is conveyed in the axial direction (the Y direction) in which the axis extends. The conveyed toner may be stored in a waste toner collection container.
[0015] The fixing device 80 fixes the toner image to the sheet 5 by passing the sheet 5 through a fixing nip region for heating and pressing the sheet. The fixing device 80 includes a heating roller 82 which heats the sheet 5 and a pressing roller 84 which is pressed against the heating roller 82 and rotationally drives the heating roller. The fixing nip region of the fixing device 80 is formed between the heating roller 82 and the pressing roller 84. The discharge device 90 includes, for example, a discharge roller 92 and a discharge roller 94 which discharge the sheet 5 to which the toner image has been fixed, to the outside of the image forming apparatus 1 .
[0016] The control unit (or controller) 100 controls the operation of the image forming apparatus 1 to operate the image forming apparatus 1 . The example control unit 100 may include, for example, an electronic control unit including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.
[0017] FIG. 2 is a schematic view showing a configuration in the vicinity of the example photoconductor 30 and of the example transfer device 60. With reference to FIG. 2, an image-forming surface 31 a is formed on the outer peripheral surface of the photoconductor drum 31 . The transfer device 60 is spaced apart from the image-forming surface 31 a of the photoconductor drum 31 to form a gap 9 in the transfer region 8.
[0018] Namely, the image-forming surface 31 a of the photoconductor drum 31 and an outer peripheral surface 62a of the transfer roller 62 of the transfer device 60 are spaced apart so as to not be in contact with each other. For example, the width of the gap 9 can be the closest distance between the image-forming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62 of the transfer device 60. The gap 9 formed in the transfer region 8 is greater than 0 mm. Accordingly, the transfer device 60 can form the gap 9 which prevents an electrical contact between the image-forming surface 31a of the photoconductor drum 31 and the transfer device 60.
[0019] The image forming apparatus 1 is set in advance to print (process) the sheet 5 having a thickness in a predetermined thickness range. The example control unit (or controller) 100 includes a storage unit (or storage device) 102. The predetermined thickness range of the sheet 5 to be printed by the image forming apparatus 1 is stored in the storage unit 102 in advance. The gap 9 in the transfer region 8 is equal to or less than the minimum thickness of the predetermined thickness range of the sheet 5 to be printed by the image forming apparatus 1 .
[0020] The example image forming apparatus 1 can print a thin sheet (for example, having a thickness of 0.06 mm) as a sheet having a predetermined minimum thickness. The size or width of the gap 9 which is the closest distance between the photoconductor drum 31 and the transfer roller 62 may be equal to or less than 0.06 mm as an example. Further, the size or width of the gap 9 which is the closest distance between the photoconductor drum 31 and the transfer roller 62 may be equal to or greater than 0.01 mm as an example.
[0021] Namely, in the example image forming apparatus 1 , the sheet 5 is brought into contact with both the transfer device 60 and the photoconductor
30 when the sheet 5 is conveyed through the gap 9.
[0022] Next, an example of a configuration in which the gap 9 is formed in the transfer region 8 will be described. The example transfer device 60 includes a spacer 64 (cf. FIG. 3) which forms the gap 9 in addition to the above-described transfer roller 62. Hereinafter, various examples of the example spacer 64 forming the gap 9 will be described.
[0023] With reference to FIG. 3, an example of the spacer 64 may include a pair of band-shaped members 65 respectively wound on the outer peripheral surfaces 62a at the two opposite ends of the transfer roller 62. Additionally, in FIG. 3, although the band-shaped member 65 provided at a first end portion of the transfer roller 62 is shown, the band-shaped member 65 is also provided at the second end portion of the transfer roller 62. The same applies to FIGS. 4 to 6 described below.
[0024] The outer peripheral surfaces of the pair of band-shaped members 65 contact the photoconductor drum 31. Namely, the outer peripheral surface of the band-shaped member 65 contacts the outer peripheral surface
31 b of the photoconductor drum 31 . Further, the outer peripheral surface of the band-shaped member 65 may contact a portion provided with the imageforming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 . Accordingly, the outer peripheral surface 62a of the transfer roller 62 does not contact the image-forming surface 31a of the photoconductor drum 31. In this way, the band-shaped member 65 that is wound on the transfer roller 62 forms the gap 9 between the image-forming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62. Since the band-shaped member 65 contacts the photoconductor drum 31 , the transfer roller 62 may rotate to follow the rotation of the photoconductor drum 31 .
[0025] In some examples, the pair of band-shaped members 65 may have an adhesive layer on the surface facing the outer peripheral surface 62a of the transfer roller 62. In this case, the band-shaped member 65 may adhere to the outer peripheral surface 62a of the transfer roller 62. Accordingly, the band-shaped member 65 can be easily attached to the outer peripheral surface 62a of the transfer roller 62.
[0026] In some examples, each of the pair of band-shaped members 65 may be wound around the outer peripheral surface 62a of the transfer roller 62 by two or more turns. Accordingly, the size of the gap 9 can be easily adjusted by adjusting the number of times of winding the band-shaped member 65.
[0027] With reference to FIG. 4, an example of the spacer 64 may include a pair of rings 66 respectively attached to the outer peripheral surfaces 62a at opposite ends of the transfer roller 62. The outer peripheral surfaces of the pair of rings 66 contact the photoconductor drum 31 . Additionally, the outer peripheral surface of the ring 66 contacts the outer peripheral surface 31 b of the photoconductor drum 31 . Further, the outer peripheral surface of the ring 66 may contact a portion provided with the image-forming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 . The ring 66 has an annular shape, and the transfer roller 62 extends through the ring 66. [0028] Accordingly, it is possible to easily form the gap 9 between the imageforming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62. Further, the size of the gap 9 in the circumferential direction of the transfer roller 62 does not change by using the ring 66 having a seamless annular shape. Since the ring 66 contacts the photoconductor drum 31 , the transfer roller 62 may rotate to follow the rotation of the photoconductor drum 31 .
[0029] With reference to FIG. 5, an example of the spacer 64 may include a pair of caps 67 respectively covering the two opposite end portions of the transfer roller 62. Each cap 67 includes an annular ring portion (ring) 67a attached to the corresponding one of the outer peripheral surfaces 62a of the two opposite ends of the transfer roller 62, and a plate portion 67b covering the end surface of the transfer roller 62. The outer peripheral surface of the ring portion 67a contacts the photoconductor drum 31 . Namely, the outer peripheral surface of the ring portion 67a contacts the outer peripheral surface 31 b of the photoconductor drum 31 . Further, the outer peripheral surface of the ring portion 67a may contact a portion provided with the image-forming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 . The transfer roller 62 extends through the ring portion 67a of the cap 67. [0030] Also in this case, it is possible to easily form the gap 9 between the image-forming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62. Further, the size of the gap 9 in the circumferential direction of the transfer roller 62 does not change by using the cap 67 with the ring portion 67a having a seamless annular shape. Since the ring portion 67a of the cap 67 contacts the photoconductor drum 31 , the transfer roller 62 may rotate to follow the rotation of the photoconductor drum 31.
[0031] With reference to FIG. 6, an example of the spacer 64 may include a pair of disks 68 respectively attached the opposite ends of a rotating shaft 63 of the transfer roller 62. The disk 68 is attached to the rotating shaft 63 in such a manner that the rotating shaft 63 extends through the center portion of the disk 68. The diameter of the disk 68 is greater than the diameter of the transfer roller 62. The outer peripheral surfaces of the pair of disks 68 contact the photoconductor drum 31. Namely, the outer peripheral surface of the disk 68 contacts the outer peripheral surface 31 b of the photoconductor drum 31 . Further, the outer peripheral surface of the disk 68 may contact a portion provided with the image-forming surface 31 a in the outer peripheral surface 31 b of the photoconductor drum 31 .
[0032] Also in this case, it is possible to easily form the gap 9 between the image-forming surface 31 a of the photoconductor drum 31 and the outer peripheral surface 62a of the transfer roller 62. Further, since the disk 68 is attached to the rotating shaft 63, it is possible to form the gap 9 without depending on the accuracy of the outer diameter of the transfer roller 62.
[0033] With reference to FIG. 7, a resistance layer 87 is provided on the outer peripheral surface of the example transfer roller 62. As an example, the transfer roller 62 includes a metal tube 86 disposed outside the rotating shaft 63 and the resistance layer 87. The metal tube 86 has a substantially cylindrical shape. The rotating shaft 63 is disposed inside the metal tube 86. Additionally, an intermediate member 88 may be provided to fill the gap between the metal tube 86 and the rotating shaft 63. In other examples, the metal tube 86 may function as the rotating shaft 63. Namely, the metal tube 86 and the rotating shaft 63 may be integrated into a single component.
[0034] The resistance layer 87 is provided on the outer peripheral surface of the metal tube 86. The resistance layer 87 is formed of, for example, resin, rubber, or the like. This rubber may have, for example, an insulator whose resistance value has been adjusted with a conductive agent or the like. The layer thickness of the example resistance layer 87 is equal to or greater than 10 pm and equal to or less than 100 pm. Further, the resistance value of the example resistance layer 87 is equal to or greater than 5 logQ and equal to or less than 10 logQ. By providing the resistance layer 87 with the abovedescribed configuration on the outer peripheral surface of the metal tube 86, it is possible to increase the accuracy of the transfer roller 62.
[0035] Additionally, a standard transfer roller which is accommodated in the image forming apparatus to contact the photoconductor drum may be used as the transfer roller 62.
[0036] The example image forming apparatus 1 performs a printing end process after the printing on the sheet 5 ends. Hereinafter, the voltage applied to the photoconductor 30 and to the transfer device 60 in the printing end process will be described. In the printing end process, static elimination is performed on the image-forming surface 31a of the photoconductor drum 31 . Further, a positive voltage and a negative voltage are alternately applied to the transfer roller 62 for cleaning the transfer roller 62. Accordingly, the toner attached to the transfer roller 62 is released from the transfer roller 62 to be removed from the transfer roller 62.
[0037] With reference to FIG. 2, the control unit 100 includes a voltage control unit (or voltage control device) 101. The voltage control unit 101 controls a voltage applied to the photoconductor drum 31 and the like.
[0038] The example printing end process will be described with reference to FIG. 8. FIG. 8 shows a state in which the printing end process starts at the time t1 . Immediately before the time t1 when the printing end process starts, the surface potential of the photoconductor drum 31 (the potential of the image-forming surface 31 a) is in a negatively charged state as a voltage level for performing printing in such a manner that the photoconductor drum is charged by the charging roller 32. The exposure device 40 is in an off state. A positive voltage is applied to the transfer roller 62 as a voltage level for performing printing. A negative voltage is applied to each of the charging roller 32 and the developing device 50 as a voltage level for performing printing.
[0039] When printing ends, the control unit 100 starts a printing end process. The voltage control unit 101 stops the application of the positive voltage to the transfer roller 62 at the time t1 . Then, the voltage control unit 101 stops the application of the negative voltage to the charging roller 32 at the time t2 and stops the application of the negative voltage to the developing device 50 at the time t3. Since the application of the negative voltage to the charging roller 32 is stopped at the time t2, the surface potential of the photoconductor drum 31 changes after the time t2, to reach 0 V.
[0040] Starting at the time t4, the control unit 100 operates the exposure device 40 to expose the image-forming surface 31 a of the photoconductor drum 31 and eliminates static electricity of the image-forming surface 31a. Accordingly, the surface potential of the photoconductor drum 31 is 0 V after the time t4. After static elimination of the photoconductor drum 31 , the control unit 100 stops the exposure device 40 at the time t5.
[0041] After static elimination of the image-forming surface 31 a of the photoconductor drum 31 is performed by the exposure device 40, the voltage control unit 101 alternately applies a positive voltage and a negative voltage to the transfer roller 62 after the time t6. Here, the gap 9 is provided between the photoconductor drum 31 and the transfer roller 62. Accordingly, the photoconductor drum 31 is not charged even when a positive voltage and a negative voltage are alternately applied to the transfer roller 62. Therefore, as shown in FIG. 8, the surface potential of the photoconductor drum 31 is 0
V even after the time t6.
[0042] With a photoconductor drum that is charged, the toner or carrier may be drawn to the charged photoconductor drum. Accordingly, when the photoconductor drum 31 is not charged as described above, the transfer of toner and carrier from the developing device 50 to the photoconductor drum 31 is prevented or suppressed. After the application of the voltage to the transfer roller 62 ends at the time t7, the control unit 100 ends the printing end process at the time t8.
[0043] Next, example experimental results in the charged state of the photoconductor drum 31 when performing the printing end process will be described with reference to FIG. 9. FIG. 9 shows the presence or absence of charging (surface charging) of the photoconductor drum 31 when a positive voltage is applied to the transfer roller 62, the presence or absence of charging (surface charging) of the photoconductor drum 31 when a negative voltage is applied to the transfer roller 62, the presence or absence of transfer failure of the toner image on the sheet 5, and the presence or absence of conveyance failure of the sheet 5.
[0044] Further, in the example image forming apparatus 1 , a minimum thickness of the predetermined thickness range of the sheet 5 to be printed, is set to 0.06 mm. Therefore, in the example image forming apparatus 1 , the gap 9 having a size greater than 0 mm and equal to or less than 0.06 mm is set as the gap 9 between the photoconductor drum 31 and the transfer roller 62. Here, an experiment was performed when the size of the gap 9 was 0.03 mm and 0.06 mm.
[0045] As shown in FIG. 9, when the size of the gap 9 was 0.03 mm and 0.06 mm, the photoconductor drum 31 was not charged even when a positive voltage and a negative voltage were applied to the transfer roller 62 during the printing end process. Additionally, when the size of the gap 9 was 0.03 mm and 0.06 mm, a transfer failure of the toner image to the sheet 5 and a conveyance failure of the sheet 5 were not generated during the printing operation of the sheet 5.
[0046] As a comparative example, an experiment was performed when there was no gap 9 (when the gap was 0 mm). Namely, the printing end process was performed while the photoconductor drum 31 and the transfer roller 62 were in contact with each other. In this case, as shown in FIG. 9, the photoconductor drum 31 was charged when a positive voltage and a negative voltage were applied to the transfer roller 62 during the printing end process. In this way, when the photoconductor drum 31 and the transfer roller 62 contact each other, the photoconductor drum 31 is charged when a voltage is applied to the transfer roller 62. Additionally, a transfer failure of the toner image to the sheet 5 and a conveyance failure of the sheet 5 were not generated during the printing operation of the sheet 5.
[0047] Additionally, an experiment was also performed when the size of the gap 9 was 0.09 mm, 0.18 mm, and 0.27 mm. In this case, as shown in FIG. 9, the photoconductor drum 31 was not charged even when a positive voltage and a negative voltage were not applied to the transfer roller 62 during the printing end process. Additionally, a transfer failure of the toner image to the sheet 5 and a conveyance failure of the sheet 5 were not generated during the printing operation of the sheet 5.
[0048] As described above, in the example image forming apparatus 1 , the transfer device 60 is provided to form the gap 9 in the transfer region 8 between the image-forming surface 31 a of the photoconductor 30 and the transfer device. Further, the gap 9 in the transfer region 8 is equal to or less than the minimum thickness of the predetermined thickness range of the sheet 5 to be printed. In this case, in the example image forming apparatus 1 , it is possible to prevent or suppress the photoconductor drum 31 from being charged even when a voltage is applied to the transfer roller 62 during the printing end process. Accordingly, in the example image forming apparatus 1 , it is possible to prevent or suppress the toner or carrier from transferring to the photoconductor drum 31 by preventing the photoconductor drum 31 from being charged.
[0049] Further, since the gap 9 is provided between the photoconductor drum 31 and the transfer roller 62, it is possible to prevent or suppress the toner from moving and adhering to the transfer roller 62 from the photoconductor drum 31 and to prevent or suppress the carrier from sticking to the photoconductor drum 31 (Dimple).
[0050] The maximum value of the size of the gap 9 is the minimum thickness of the predetermined thickness range of the sheet 5 to be printed. In this case, the image forming apparatus 1 can prevent the photoconductor drum 31 from being charged during the printing end process while preventing or suppressing a transfer failure of the toner image to the sheet 5 and a conveyance failure of the sheet 5 during the printing operation of the sheet 5. [0051] The example image forming apparatus 1 removes static electricity from the photoconductor drum 31 by exposing the photoconductor drum with the exposure device 40 during the printing end process. Accordingly, the image forming apparatus 1 does not need to include a static elimination device for performing static elimination on the photoconductor drum 31 in addition to the exposure device 40.
[0052] It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted.

Claims

1 . An image forming apparatus comprising: a photoconductor having an image-forming surface to form a toner image; and a transfer device located adjacent to the photoconductor to transfer the toner image to a print medium that is conveyed through a transfer region located between the photoconductor and the transfer device, wherein the transfer device is spaced apart from the image-forming surface of the photoconductor to form a gap at the transfer region, wherein the image forming apparatus is set to process print media having thicknesses within a predetermined thickness range, and wherein the gap at the transfer region is equal to or less than a minimum thickness of the predetermined thickness range.
2. The image forming apparatus according to claim 1 , wherein the photoconductor includes a photoconductor drum forming the image-forming surface, and wherein the transfer device includes a transfer roller and a spacer coupled to the transfer roller to form the gap between the image-forming surface of the photoconductor drum and the transfer roller.
3. The image forming apparatus according to claim 2, wherein the spacer includes a pair of band-shaped members wound on an outer peripheral surface at two opposite ends, respectively, of the transfer roller, and wherein the pair of band-shaped members contact the photoconductor drum.
4. The image forming apparatus according to claim 3, wherein the pair of band-shaped members are adhered to the outer peripheral surface of the transfer roller via an adhesive layer.
5. The image forming apparatus according to claim 4, wherein each of the pair of band-shaped members is wound around the outer peripheral surface of the transfer roller by two or more turns.
6. The image forming apparatus according to claim 2, wherein the spacer includes a pair of rings respectively attached to an outer peripheral surface at two opposite ends, respectively, of the transfer roller, and wherein the pair of rings contact the photoconductor drum.
7. The image forming apparatus according to claim 2, wherein the spacer includes a pair of disks respectively attached at two opposite ends of a rotating shaft of the transfer roller, and wherein the pair of disks contact the photoconductor drum.
8. The image forming apparatus according to claim 2, wherein the closest distance between the photoconductor drum and the transfer roller is equal to or less than 0.06 mm.
9. The image forming apparatus according to claim 2, wherein the closest distance between the photoconductor drum and the transfer roller is equal to or greater than 0.01 mm.
10. The image forming apparatus according to claim 2, wherein a resistance layer is provided on an outer peripheral surface of the transfer roller, and wherein the resistance layer has a resistance value that is equal to or greater than 5 logQ, and that is equal to or less than 10 logQ.
11 . The image forming apparatus according to claim 2, wherein a resistance layer is provided on an outer peripheral surface of the transfer roller, and wherein a layer thickness of the resistance layer is equal to or greater than 10 pm, and equal to or less than 100 pm.
12. The image forming apparatus according to claim 1 , comprising: a controller which operates the image forming apparatus, wherein the controller includes a storage device storing the predetermined thickness range of the print media to be processed.
13. The image forming apparatus according to claim 2, comprising: an exposure device to direct a light to the image-forming surface of the photoconductor drum, in order to perform static elimination on the imageforming surface.
14. The image forming apparatus according to claim 13, comprising: a voltage control device to control a voltage applied to the transfer roller, the voltage control device to alternately apply a positive voltage and a negative voltage to the transfer roller after static elimination is performed on the image-forming surface of the photoconductor drum by the exposure device.
15. An image forming apparatus comprising: a photoconductor having an image-forming surface forming a toner image; and a transfer device located adjacent to the photoconductor to transfer the toner image to a print medium having a thickness in a predetermined thickness range that is set in the image forming apparatus in advance, wherein the transfer device is spaced apart from the image-forming surface of the photoconductor to form a gap that prevents electrical contact between the image-forming surface of the photoconductor and the transfer device, wherein the closest distance between the image-forming surface of the photoconductor and the transfer device is equal to or less than a minimum thickness of the predetermined thickness range to cause the print medium to contact both the transfer device and the photoconductor when the print medium is conveyed through the gap.
21
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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04242276A (en) * 1991-01-17 1992-08-28 Fuji Xerox Co Ltd Image forming device
US5412460A (en) * 1992-10-20 1995-05-02 Mita Industrial Co., Ltd. Image transfer unit for image forming apparatus
JPH1097145A (en) * 1996-09-25 1998-04-14 Mita Ind Co Ltd Turning part supporting device for image forming device
JPH112946A (en) * 1997-06-10 1999-01-06 Konica Corp Image forming device
US20060120759A1 (en) * 2004-12-02 2006-06-08 Oki Data Corporation Image forming apparatus and charging method
JP2006201228A (en) * 2005-01-18 2006-08-03 Seiko Epson Corp Image forming apparatus
US20080057289A1 (en) * 2006-09-05 2008-03-06 Fuji Xerox Co., Ltd. Transfer roll and image forming apparatus
US20170212454A1 (en) * 2016-01-26 2017-07-27 Fuji Xerox Co., Ltd. Image forming apparatus

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04242276A (en) * 1991-01-17 1992-08-28 Fuji Xerox Co Ltd Image forming device
US5412460A (en) * 1992-10-20 1995-05-02 Mita Industrial Co., Ltd. Image transfer unit for image forming apparatus
JPH1097145A (en) * 1996-09-25 1998-04-14 Mita Ind Co Ltd Turning part supporting device for image forming device
JPH112946A (en) * 1997-06-10 1999-01-06 Konica Corp Image forming device
US20060120759A1 (en) * 2004-12-02 2006-06-08 Oki Data Corporation Image forming apparatus and charging method
JP2006201228A (en) * 2005-01-18 2006-08-03 Seiko Epson Corp Image forming apparatus
US20080057289A1 (en) * 2006-09-05 2008-03-06 Fuji Xerox Co., Ltd. Transfer roll and image forming apparatus
US20170212454A1 (en) * 2016-01-26 2017-07-27 Fuji Xerox Co., Ltd. Image forming apparatus

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