WO2016067841A1 - 画像形成装置 - Google Patents
画像形成装置 Download PDFInfo
- Publication number
- WO2016067841A1 WO2016067841A1 PCT/JP2015/078231 JP2015078231W WO2016067841A1 WO 2016067841 A1 WO2016067841 A1 WO 2016067841A1 JP 2015078231 W JP2015078231 W JP 2015078231W WO 2016067841 A1 WO2016067841 A1 WO 2016067841A1
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- WIPO (PCT)
- Prior art keywords
- transfer
- image forming
- power supply
- forming apparatus
- supply device
- Prior art date
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/80—Details relating to power supplies, circuits boards, electrical connections
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
- G03G15/0142—Structure of complete machines
- G03G15/0178—Structure of complete machines using more than one reusable electrographic recording member, e.g. one for every monocolour image
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
- G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
- G03G15/1605—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer using at least one intermediate support
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/50—Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control
- G03G15/5004—Power supply control, e.g. power-saving mode, automatic power turn-off
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/75—Details relating to xerographic drum, band or plate, e.g. replacing, testing
- G03G15/751—Details relating to xerographic drum, band or plate, e.g. replacing, testing relating to drum
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/75—Details relating to xerographic drum, band or plate, e.g. replacing, testing
- G03G15/757—Drive mechanisms for photosensitive medium, e.g. gears
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- 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
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
- G03G15/0142—Structure of complete machines
- G03G15/0178—Structure of complete machines using more than one reusable electrographic recording member, e.g. one for every monocolour image
- G03G15/0189—Structure of complete machines using more than one reusable electrographic recording member, e.g. one for every monocolour image primary transfer to an intermediate transfer belt
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/14—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base
- G03G15/16—Apparatus for electrographic processes using a charge pattern for transferring a pattern to a second base of a toner pattern, e.g. a powder pattern, e.g. magnetic transfer
- G03G15/1665—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
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/65—Apparatus which relate to the handling of copy material
- G03G15/6555—Handling of sheet copy material taking place in a specific part of the copy material feeding path
- G03G15/657—Feeding path after the transfer point and up to the fixing point, e.g. guides and feeding means for handling copy material carrying an unfused toner image
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- 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
- G03G21/0005—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium
- G03G21/0011—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge for removing solid developer or debris from the electrographic recording medium using a blade; Details of cleaning blades, e.g. blade shape, layer forming
- G03G21/0017—Details relating to the internal structure or chemical composition of the blades
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- 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
Definitions
- the present invention relates to an image forming apparatus.
- a charging system with a small amount of ozone generation is often adopted as a system for charging a photosensitive drum (photosensitive body).
- a DC charging roller system is known as a charging system that generates a small amount of ozone.
- an image forming apparatus adopting the DC charging roller method has a lower charging capability to the photosensitive drum than an image forming apparatus adopting the conventional charging method (scorotron method). For this reason, in the DC charging roller type image forming apparatus, the charge applied to the surface of the photosensitive drum by the transfer electric field may not be canceled by the charging process in the next step.
- Patent Document 1 An invention for solving this problem is described in Patent Document 1.
- Patent Document 1 describes a tandem-type image forming apparatus which performs charge removal before transfer on a positively charged photosensitive drum.
- the image forming apparatus described in Patent Document 1 includes a plurality of image forming units corresponding to the respective colors along the circumferential direction (traveling direction) of the intermediate transfer belt.
- the charge removing device provided in each image forming unit applies light to the photosensitive drum adjacent on the upstream side with respect to the circumferential direction of the intermediate transfer belt.
- the charge removal device located between the adjacent photosensitive drums also irradiates light to the adjacent photosensitive drums with respect to the circumferential direction of the intermediate transfer belt. Do.
- the surface of the photosensitive drum carrying the toner image (the surface of the photosensitive drum before the toner image is transferred) is neutralized, and the generation of the transfer memory is suppressed.
- the toner image is not transferred onto the photosensitive drum positioned most upstream with respect to the circumferential direction of the intermediate belt. There is no charge removal. Therefore, when the toner image is transferred to the intermediate transfer belt, the surface potential of the photosensitive drum located most upstream may be higher than the surface potential of the other photosensitive drums. In such a state, when a bias voltage is applied to each primary transfer roller from one transfer power supply device, the value of the current flowing into the most upstream photosensitive drum flows into the other photosensitive drum It can be greater than the value of the current. As a result, transfer memory may be generated.
- An object of the present invention is to provide an image forming apparatus capable of reducing the size and cost of the image forming apparatus while suppressing the generation of a transfer memory.
- the image forming apparatus is an image forming apparatus that forms an image by transferring a toner image in an overlapping manner on a transfer target.
- the image forming apparatus includes a plurality of photosensitive drums, a plurality of charge removing devices, a plurality of transfer rollers, a transfer power supply device, and a plurality of load resistors.
- the plurality of photosensitive drums are disposed along the traveling direction of the transfer target.
- the plurality of charge removal devices are disposed on the downstream side of each of the plurality of photosensitive drums along the traveling direction of the transfer target, and respectively discharge the photosensitive drums positioned on the upstream side.
- the plurality of transfer rollers are disposed to face each of the plurality of photosensitive drums.
- the transfer power supply device applies a potential to at least two transfer rollers including the transfer roller positioned most upstream in the traveling direction of the transfer body among the plurality of transfer rollers.
- the plurality of load resistors are connected in series between each of the transfer rollers to which a potential is applied from the transfer power supply device and the transfer power supply device, and are connected in parallel with each other.
- the charge removal device positioned between the adjacent photosensitive drums in the direction of movement of the transfer target is the one relative to the direction of movement of the transfer target among the adjacent photosensitive drums.
- the photosensitive drum located downstream is further neutralized.
- the image forming apparatus of the present invention downsizing and cost reduction of the image forming apparatus can be achieved while suppressing the generation of the transfer memory.
- FIG. 1 is a schematic view showing an image forming apparatus according to an embodiment of the present invention.
- FIG. 2 is a schematic view showing a part of an image forming unit according to Embodiment 1 of the present invention. It is a figure which shows the graph on which the value of the electric current which flows into the photoreceptor drum concerning Embodiment 1 of this invention was plotted with respect to the bias voltage. It is a figure which shows the graph on which the value of the electric current which flows into the photoreceptor drum concerning Embodiment 1 of this invention was plotted with respect to the bias voltage.
- FIG. 8 is a schematic view showing another example of the image forming unit according to Embodiment 1 of the present invention.
- FIG. 6 is a schematic view showing a part of an image forming unit according to Embodiment 2 of the present invention.
- FIG. 1 is a schematic view showing an image forming apparatus 1.
- the image forming apparatus 1 is a tandem type multifunction peripheral.
- the image forming apparatus 1 includes a conveyance unit L, a control unit 10, a sheet feeding unit 20, an image forming unit 30, a fixing unit 60, and a discharge unit 70.
- the conveyance unit L conveys the sheet S from the paper supply unit 20 to the discharge unit 70 via the fixing unit 60.
- the control unit 10 has a storage area.
- the storage area stores programs, setting information, and the like.
- the storage area is configured of an HDD (Hard Disk Drive), a RAM (Random Access Memory), and a ROM (Read Only Memory).
- the control unit 10 controls the operation of each unit of the image forming apparatus 1 by executing a control program stored in advance in the storage area.
- the sheet feeding unit 20 has a sheet feeding cassette 21 and a sheet feeding roller group 22.
- the sheet feeding cassette 21 can accommodate a plurality of sheets S.
- the sheet feeding roller group 22 feeds the sheets S stored in the sheet feeding cassette 21 to the conveyance unit L one by one.
- the sheet S is an example of a recording medium.
- the image forming unit 30 forms an image on the fed sheet S.
- the image forming unit 30 includes four toner supply devices 31y, 31c, 31m, and 31k, an exposure device 32, four image forming units 40y, 40c, 40m, and 40k, and a transfer unit 50.
- the toner supply device 31y supplies yellow toner to the corresponding image forming unit 40y.
- the toner supply devices 31c, 31m, and 31k supply cyan, magenta, and black toners to the corresponding image forming units 40c, 40m, and 40k, respectively.
- the image forming unit 40y forms a yellow toner image.
- the image forming units 40c, 40m, and 40k form cyan, magenta, and black toner images, respectively.
- the image forming units 40y, 40c, 40m, and 40k have substantially the same configuration except for the color of the toner image to be formed. Therefore, in the following description, when the matters common to the respective image forming units 40y, 40c, 40m, and 40k are described, they are referred to as the image forming unit 40.
- the exposure device 32 irradiates the photosensitive drum 41 of the image forming unit 40 with laser light for exposure. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 41.
- the transfer unit 50 includes an intermediate transfer belt 51.
- the transfer unit 50 superimposes and transfers the toner images formed by the image forming units 40 y, 40 c, 40 m, and 40 k onto the sheet S via the intermediate transfer belt 51.
- the sheet S on which the toner image has been transferred is conveyed to the fixing unit 60.
- the fixing unit 60 includes a heating member 61 and a pressure member 62.
- the fixing unit 60 fixes the unfixed toner image on the sheet S by heating and pressing the sheet S by the heating member 61 and the pressing member 62.
- the discharge unit 70 discharges the sheet S to the outside of the apparatus main body.
- FIG. 2 is a view showing a part of the image forming unit 30. As shown in FIG.
- the image forming units 40 y, 40 c, 40 m and 40 k are disposed along the intermediate transfer belt 51. Specifically, the image forming units 40y, 40c, 40m and 40k are arranged adjacent to each other in this order from the upstream side to the downstream side of the circumferential direction D (traveling direction) of the intermediate transfer belt 51.
- the image forming unit 40y includes a charging device 42y, a developing device 44y, a charge removing device 45y, and a cleaning device 46y in addition to the photosensitive drum 41y.
- the image forming units 40c, 40m and 40k are added to the photosensitive drums 41c, 41m and 41k, and charging devices 42c, 42m and 42k, developing devices 44c, 44m and 44k, and charge removing devices 45c, 45m, 45k and
- the cleaning devices 46c, 46m and 46k are provided respectively.
- the photosensitive drums 41 y, 41 c, 41 m, and 41 k have substantially the same configuration. Therefore, when describing matters common to the photosensitive drums 41 y, 41 c, 41 m, and 41 k, the photosensitive drums 41 are described.
- the charging devices 42y, 42c, 42m and 42k have substantially the same configuration. Therefore, when the matters common to the charging devices 42y, 42c, 42m, and 42k are described, the charging device 42 is described.
- the developing devices 44y, 44c, 44m and 44k have substantially the same configuration. Therefore, when the matters common to the developing devices 44y, 44c, 44m, and 44k are described, the developing devices 44 are described.
- the charge removal devices 45y, 45c, 45m and 45k have substantially the same configuration.
- the charge removal device 45 is described. Furthermore, the cleaning devices 46y, 46c, 46m and 46k have substantially the same configuration. Therefore, when the matters common to the cleaning devices 46y, 46c, 46m and 46k are described, the cleaning devices 46 are described.
- the photosensitive drum 41 rotates in the rotational direction R and carries a toner image and an electrostatic latent image.
- the charging device 42, the developing device 44, the charge removing device 45, and the cleaning device 46 are disposed to face the circumferential surface of the photosensitive drum 41. Specifically, the charging device 42, the developing device 44, the charge removing device 45, and the cleaning device 46 are disposed in this order along the rotational direction R of the photosensitive drum 41.
- the charging device 42 charges the photosensitive drum 41 to a predetermined potential.
- the charging device 42 charges the photosensitive drum 41 to a predetermined positive potential by a roller charging method.
- the developing device 44 discharges the toner onto the photosensitive drum 41. As a result, the electrostatic latent image formed on the photosensitive drum 41 is developed. As a result, toner images of the respective colors are formed on the photosensitive drums 41 y, 41 c, 41 m, and 41 k, respectively.
- the charge removing device 45y is disposed between the adjacent photosensitive drum 41y and the photosensitive drum 41c.
- the charge removing device 45c is disposed between the adjacent photosensitive drum 41c and the photosensitive drum 41m.
- the charge removing device 45m is disposed between the adjacent photosensitive drum 41m and the photosensitive drum 41k.
- the charge removing device 45 k is disposed on the downstream side of the photosensitive drum 41 k with respect to the circumferential direction D of the intermediate transfer belt 51.
- the charge removal devices 45y, 45c, 45m and 45k remove the charge on the surfaces of the photosensitive drums 41y, 41c, 41m and 41k after the toner image is transferred to the intermediate transfer belt 51 (hereinafter referred to as erase after transfer) There is As a result, the surface potential of the photosensitive drum 41 becomes approximately 0V. Further, the charge removing devices 45y, 45c and 45m excluding the charge removing device 45k further discharge the photosensitive drums 41c, 41m and 41k before the toner image is transferred to the intermediate transfer belt 51 (hereinafter referred to as erase before transfer). There is a case).
- the charge removal devices 45y, 45c, 45m are located on the downstream side of the charge removal devices 45y, 45c, 45m with respect to the circumferential direction D of the intermediate transfer belt 51 (an example of the transfer target) , 41k is further discharged.
- the potential of the portion of the surface of each of the photosensitive drums 41c, 41m, and 41k on which the toner image is not carried decreases.
- the surface potential of the photosensitive drum 41y may be higher than the surface potentials of the other photosensitive drums 41c, 41m, and 41k.
- the cleaning device 46 has a cleaning blade.
- the cleaning blade abuts on the surface of the corresponding photosensitive drum 41 to scrape off the toner remaining on the surface of the photosensitive drum 41. Thus, the toner remaining on the surface of the photosensitive drum 41 is removed.
- the transfer unit 50 includes, in addition to the intermediate transfer belt 51, a drive roller 52, a driven roller 53, four primary transfer rollers 54y, 54c, 54m, and 54k, which are an example of a plurality of transfer rollers, and a first transfer power supply device. And a secondary transfer roller 56, and four load resistors 57y, 57c, 57m, and 57k.
- the primary transfer rollers 54y, 54c, 54m and 54k have substantially the same configuration. Therefore, when the matters common to the primary transfer rollers 54 y, 54 c, 54 m, 54 k are described, the primary transfer roller 54 is referred to.
- the load resistors 57y, 57c, 57m and 57k have substantially the same configuration. Therefore, when the matters common to the load resistors 57y, 57c, 57m, and 57k are described, the load resistors 57 are described.
- the toner images of the respective colors formed on the respective photosensitive drums 41 y, 41 c, 41 m and 41 k are superimposed and transferred onto the intermediate transfer belt 51.
- the thickness of the intermediate transfer belt 51 is, for example, about 80 ⁇ m to 120 ⁇ m.
- the intermediate transfer belt 51 includes a base layer in which carbon, which is an example of conductive particles, is dispersed in a base material such as polyamide (PA).
- the intermediate transfer belt 51 further includes an insulating resin layer covering the surface of the base layer.
- the insulating resin layer is made of, for example, polycarbonate (PC), acrylic, or fluorine-based resin.
- the thickness of the insulating resin layer is about several ⁇ m.
- the driving roller 52 receives a driving force from the driving source and rotates.
- the driving roller 52 and the driven roller 53 stretch the intermediate transfer belt 51.
- the driven roller 53 is driven to rotate by the rotation of the drive roller 52.
- the driving roller 52 and the driven roller 53 circulate the intermediate transfer belt 51 in the circumferential direction D.
- the primary transfer roller 54 is an elastic roller whose surface resistivity is adjusted.
- the primary transfer roller 54 includes a core metal and an elastic layer covering the outer peripheral surface of the core metal.
- the elastic layer is made of carbon-dispersed conductive rubber in which carbon, which is an example of conductive particles, is dispersed in an elastic material.
- the elastic material is ethylene propylene rubber (EPDM) or nitrile rubber (NBR).
- the thickness of the elastic layer is about 3 mm.
- the surface resistivity of each of the primary transfer rollers 54 y, 54 c, 54 m, 54 k at the time of 1000 V application is 1.0 ⁇ 10 6 ⁇ / sq or more.
- the primary transfer rollers 54y, 54c, 54m and 54k are disposed to face the photosensitive drums 41y, 41c, 41m and 41k via the intermediate transfer belt 51, respectively.
- the primary transfer rollers 54y, 54c, 54m and 54k are arranged such that the position of the rotation axis thereof is offset from the position of the rotation axis of the opposing photosensitive drum 41.
- the primary transfer roller 54 is offset to the downstream side from the rotational axis of the photosensitive drum 41 opposed to the circumferential direction D of the intermediate transfer belt 51.
- the rotation axis of the primary transfer roller 54 is offset by 4 mm downstream from the rotation axis of the opposing photosensitive drum 41 in the circumferential direction D of the intermediate transfer belt 51.
- the amount by which the rotation axis of the primary transfer roller 54 is offset from the rotation axis of the photosensitive drum 41 in the circumferential direction D of the intermediate transfer belt 51 is referred to as an offset amount.
- the transfer power supply 55a applies a negative potential to all the primary transfer rollers 54.
- the transfer power supply device 55a is a constant voltage source, and applies a bias voltage to each of the primary transfer rollers 54y, 54c, 54m and 54k.
- an electric field transfer electric field (transfer electric field) is generated between the primary transfer roller 54y and the photosensitive drum 41y corresponding to the primary transfer roller 54y. ) Occurs.
- an electric field (transfer electric field) is generated between the primary transfer rollers 54c, 54m, 54k and the photosensitive drums 41c, 41m, 41k corresponding to the primary transfer rollers 54c, 54m, 54k.
- the toner images formed on the surfaces of the photosensitive drums 41 y, 41 c, 41 m, and 41 k are transferred to the intermediate transfer belt 51 by the transfer electric field.
- the voltage value of the bias voltage is, for example, minus 1600 V.
- the load resistor 57y is connected in series between the corresponding primary transfer roller 54y and the transfer power supply 55a.
- the load resistors 57c, 57m, 57k are connected in series between the corresponding primary transfer rollers 54c, 54m, 54k and the transfer power supply 55a.
- the load resistors 57y, 57c, 57m, and 57k are connected in parallel to one another.
- Each of the load resistors 57y, 57c, 57m, 57k has a resistance value greater than the smallest system resistance value.
- the system resistance value is obtained from the relationship (I-V characteristic) between the bias voltage generated from the transfer power supply device 55a and the current value of the current flowing through each of the photosensitive drums 41y, 41m, 41c, 41k.
- the system resistance value is smallest when the film thickness of the photosensitive layer of the photosensitive drum is the smallest and the potential of the surface of the photosensitive drum is the highest.
- the surface potential of the photosensitive drum 41y on which erasing before transfer is not performed is the highest. Therefore, when the film thickness of the photosensitive layer of the photosensitive drum 41y becomes the thinnest, the system resistance value becomes the smallest.
- each of the load resistors 57y, 57c, 57m, 57k is reduced by making it larger than the smallest system resistance value.
- the resistance value of each of the load resistors 57 y, 57 c, 57 m and 57 k is 1 ⁇ 10 8 ⁇ or more.
- the resistance values of the load resistors 57y, 57c, 57m, and 57k may be different from one another.
- the load resistance 57 may be smaller in order from the load resistance 57 y located most upstream with respect to the winding direction D of the intermediate transfer belt 51.
- the toner image transferred to the intermediate transfer belt 51 increases in thickness as it goes downstream. For this reason, it is preferable that a current larger than that of each of the primary transfer rollers 54 y, 54 c, and 54 m adjacent on the upstream side flow through each of the primary transfer rollers 54 c, 54 m, and 54 k.
- each primary transfer roller 54c by decreasing the resistance values of the load resistors 57y, 57c, 57m and 57k in order from the load resistor 57y positioned most upstream with respect to the winding direction D of the intermediate transfer belt 51, each primary transfer roller 54c, The current value of the current flowing through 54m, 54k becomes larger than the current value of the current flowing through each of the primary transfer rollers 54y, 54c, 54m adjacent on the upstream side. As a result, the toner image is more reliably transferred to the intermediate transfer belt 51.
- the secondary transfer roller 56 is pressed by the driven roller 53 to form a nip portion N with the driven roller 53.
- the secondary transfer roller 56 and the driven roller 53 transfer the toner image on the intermediate transfer belt 51 to the sheet S when the sheet S passes through the nip portion N.
- FIG. 3 shows a graph (IV characteristic) in which the current value of the current flowing to the photosensitive drum 41y is plotted against the bias voltage.
- the horizontal axis indicates the voltage value Vp (V) of the bias voltage generated from the transfer power supply device 55a
- the vertical axis indicates the current value Ip ( ⁇ A) of the current flowing through the photosensitive drum 41y.
- the current value Ip is a value measured between the connection point P1 and the load resistor 57y.
- the connection point P1 is a connection point between the transfer power supply device 55a and the load resistors 57y, 57c, 57m and 57k.
- the voltage value Vp (V) and the current value Ip ( ⁇ A) both indicate absolute values.
- a broken line L31 shown in FIG. 3 indicates the current value Ip of the current flowing through the photosensitive drum 41y when the load resistor 57 is not connected between the primary transfer roller 54 and the transfer power supply device 55a.
- the broken line L32 represents the current flowing to the photosensitive drum 41y when the load resistors 57y, 57c, 57m, 57k are connected in series between the primary transfer rollers 54y, 54c, 54m, 54k and the transfer power supply 55a.
- the current value Ip is shown.
- the photosensitive drum 41y, 41c will be described as an example. More specifically, when the load resistance 57 is not connected between the primary transfer roller 54 and the transfer power supply 55a, the load resistances 57y, 57c, 57m, between the primary transfer roller 54 and the transfer power supply 55a. Compare with the case where 57k are connected in series.
- FIG. 4 shows a graph (IV characteristic) in which the values of the current flowing to the photosensitive drums 41 y and 41 c are plotted against the voltage value Vp of the bias voltage.
- the horizontal axis indicates the voltage value Vp (V) of the bias voltage generated from the transfer power supply device 55a
- the vertical axis indicates the current value Ip ( ⁇ A) of the current flowing through the photosensitive drums 41y and 41c.
- the current value Ip of the current flowing to the photosensitive drum 41y is measured between the connection point P1 and the load resistor 57y.
- the current value Ip of the current flowing to the photosensitive drum 41c is a value measured between the connection point P1 and the load resistor 57c.
- the voltage value Vp (V) of the bias voltage indicates an absolute value.
- a broken line L41 shown in FIG. 4 indicates the current value Ip of the current flowing through the photosensitive drum 41y when the load resistor 57 is not connected between the transfer power supply 55a and the primary transfer roller 54. Specifically, a broken line L41 indicates the current value Ip of the current flowing through the photosensitive drum 41y when the film thickness of the photosensitive layer of the photosensitive drum 41y is the thinnest.
- a broken line L42 indicates the current value Ip of the current flowing through the photosensitive drum 41c when the load resistor 57 is not connected between the transfer power supply 55a and the primary transfer roller 54. Specifically, the broken line L42 indicates the current value Ip of the current flowing through the photosensitive drum 41c when the film thickness of the photosensitive layer of the photosensitive drum 41c is the thickest.
- a broken line L43 represents the current value Ip of the current flowing through the photosensitive drum 41y when the load resistors 57y, 57c, 57m and 57k are connected between the transfer power supply device 55a and the primary transfer rollers 54y, 54c, 54m and 54k. Indicates Specifically, when the film thickness of the photosensitive layer of the photosensitive drum 41 y is the thinnest, the broken line L 43 indicates the current value Ip of the current flowing through the photosensitive drum 41 y.
- the broken line L44 represents the current value Ip of the current flowing through the photosensitive drum 41c when the load resistors 57y, 57c, 57m and 57k are connected between the transfer power supply device 55a and the primary transfer rollers 54y, 54c, 54m and 54k. Indicates Specifically, when the film thickness of the photosensitive layer of the photosensitive drum 41c is the thickest, the broken line L44 indicates the current value Ip of the current flowing through the photosensitive drum 41c.
- the maximum difference between the current value Ip of the current flowing to the photosensitive drum 41y (broken line L41) and the current flowing to the photosensitive drum 41c (broken line L42) is The voltage value Vp is about 30 ⁇ A in the vicinity of 2200 V.
- the difference between the current value Ip between the current flowing to the photosensitive drum 41 y (broken line L44) and the current flowing to the photosensitive drum 41 c (broken line L43) is the voltage value Vp. Is about 4.0 ⁇ A or less at around 2200 V.
- the surface potential of the photosensitive drum 41y for which erasing before transfer is not performed is the highest. Further, the surface potentials of the photosensitive drums 41c, 41m and 41k for which the pre-transfer erase is executed are approximately the same. Accordingly, the current values of the currents flowing to the photosensitive drums 41c, 41m, and 41k are approximately the same. As a result, the difference between the current value Ip of the current flowing to the photosensitive drum 41y and the current value of the current flowing to the photosensitive drums 41m and 41k is the difference between the current value Ip of the current flowing to the photosensitive drum 41y and the photosensitive drum 41c.
- the difference is approximately the same as the difference between the flowing current and the current value Ip. Therefore, according to the present embodiment, the current value of the current flowing to each of the photosensitive drums 41 y, 41 c, 41 m, and 41 k is suppressed to be low and uniform.
- the load resistors 57y, 57c, 57m, 57k are connected in series between the primary transfer rollers 54y, 54c, 54m, 54k and the transfer power supply 55a.
- the current flowing to each of the photosensitive drums 41y, 41c, 41m, 41k The current value can be kept low and equalized. Therefore, even if a bias voltage is applied to a plurality of primary transfer rollers 54 from one transfer power supply device 55a, the occurrence of transfer memory can be suppressed.
- the base material included in the intermediate transfer belt 51 is polyamide (PA)
- PA polyamide
- the base material is not limited to polyamide.
- PC polycarbonate
- PI polyimide
- PA alloy polyamide alloy
- the base material included in the intermediate transfer belt 51 is a thermoplastic resin such as polyamide
- the base material may be a thermosetting resin instead of the thermoplastic resin.
- the offset amount is 4 mm, but the offset amount is not limited to 4 mm.
- the offset amount may be 3 mm or 7 mm.
- the primary transfer rollers 54y, 54c, 54m, 54k are offset downstream with respect to the circumferential direction D of the intermediate transfer belt 51, but the primary transfer rollers 54y, 54c, 54m, 54 k may be offset upstream with respect to the circumferential direction D of the intermediate transfer belt 51.
- the charging device 42 charges the photosensitive drum 41 by a roller method, but the method of charging the photosensitive drum 41 by the charging device 42 is not limited to this.
- the charging device 42 may charge the photosensitive drum 41 by a wire method.
- the load resistors 57y, 57c, 57m, and 57k are connected in series between the primary transfer rollers 54y, 54c, 54m, and 54k and the transfer power supply device 55a.
- the variable resistors 59y, 59m, 59c, 59k are replaced by the primary transfer rollers 54y, 54c, 54m, 54k and the transfer power supply 55a instead of the load resistors 57y, 57c, 57m, 57k. It may be connected between.
- the transfer unit 50 further includes a resistor 58 provided between the transfer power supply 55a and the connection point P1.
- the resistor 58 has a resistance value equal to the smallest system resistance value.
- FIG. 6 is a schematic view showing a part of the image forming unit 30 according to the second embodiment.
- the image forming unit 30 (transfer unit 50) includes the transfer power supply 55b in addition to the transfer power supply 55a.
- a bias voltage is applied to the primary transfer roller 54k from the transfer power supply device 55b.
- the transfer power supply device 55a applies a bias voltage to the primary transfer rollers 54y, 54c, 54m located upstream of the primary transfer roller 54k. That is, the transfer power supply device 55a includes at least two primary transfer rollers (in the present embodiment, the primary transfer roller 54y) including the primary transfer roller 54y positioned most upstream with respect to the circumferential direction D of the intermediate transfer belt 51. , 54c, 54m) are applied with a bias voltage.
- the transfer power supply device 55b is connected in series with the primary transfer roller 54k positioned most downstream with respect to the circumferential direction D of the intermediate transfer belt 51, and applies a bias voltage to the primary transfer roller 54k.
- the image forming apparatus 1 further includes the transfer power supply 55b in addition to the transfer power supply 55a.
- the image forming apparatus 1 applies the bias voltage to the primary transfer roller 54k without applying a bias voltage to each of the primary transfer rollers 54y, 54c, and 54m. Only bias voltage can be applied. As a result, the power consumption of the image forming apparatus 1 can be reduced.
- a load resistor 57k may be connected in series between the transfer power supply 55b and the primary transfer roller 54k.
- the present invention is also applicable to a direct transfer belt type image forming apparatus.
- a recording medium such as the sheet S is a transferee.
- the transfer power supply devices 55a and 55b are constant voltage sources in the embodiment of the present invention, the transfer power supply devices 55a and 55b may be constant current sources.
- the present invention is applied to a multifunction machine, but the present invention is also applicable to a copier, a printer, or the like.
- the present invention is applicable to the field of image forming apparatuses.
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Abstract
Description
図1を参照して、画像形成装置1について説明する。図1は、画像形成装置1を示す模式図である。本実施形態において、画像形成装置1は、タンデム方式の複合機である。
次に、図1及び図6を参照して、本発明の実施形態2に係る画像形成装置1について説明する。図6は、実施形態2に係る画像形成部30の一部を示す模式図である。実施形態2では、画像形成部30(転写部50)が転写電源装置55aに加えて、転写電源装置55bを備える。詳しくは、実施形態2では、1次転写ローラー54kに、転写電源装置55bからバイアス電圧が印加される。以下、実施形態2について実施形態1と異なる事項を説明し、実施形態1と重複する事項の説明は割愛する。
Claims (12)
- 被転写体にトナー像を重ねて転写することによって画像を形成する画像形成装置であって、
前記被転写体の進行方向に沿って配置される複数の感光体ドラムと、
前記被転写体の進行方向に沿って前記複数の感光体ドラムのそれぞれの下流側に配置され、上流側に位置する前記感光体ドラムをそれぞれ除電する複数の除電装置と、
前記複数の感光体ドラムのそれぞれに対向して配置される複数の転写ローラーと、
前記複数の転写ローラーのうち、前記被転写体の進行方向において最も上流側に位置する前記転写ローラーを含む少なくとも2つの前記転写ローラーにそれぞれ電位を付与する第1転写電源装置と、
前記第1転写電源装置から電位が付与される前記転写ローラーのそれぞれと前記第1転写電源装置との間に直列に接続され、且つ、互いに並列に接続される複数の負荷抵抗と
を備え、
前記複数の除電装置のうち、前記被転写体の進行方向において隣接する前記感光体ドラムの間に位置する前記除電装置は、隣接する前記感光体ドラムのうち、前記被転写体の進行方向に対して下流側に位置する前記感光体ドラムを更に除電する、画像形成装置。 - 前記複数の負荷抵抗のそれぞれは、システム抵抗値よりも大きい抵抗値を有し、
前記システム抵抗値は、前記複数の負荷抵抗がそれぞれ接続される1つの前記転写ローラーの抵抗値と、前記転写ローラーにそれぞれ対向する1つの前記感光体ドラムの抵抗値とを含む、請求項1に記載の画像形成装置。 - 前記システム抵抗値はそれぞれ、前記被転写体の抵抗値を更に含む、請求項2に記載の画像形成装置。
- 前記負荷抵抗値のそれぞれは、最も小さい前記システム抵抗値よりも大きい抵抗値を有する、請求項2に記載の画像形成装置。
- 前記第1転写電源装置と前記第1転写電源装置から電位が付与される前記転写ローラーとの間に接続される前記負荷抵抗の抵抗値は、前記被転写体の進行方向において最も上流側に位置する前記負荷抵抗から順に小さくなる、請求項1に記載の画像形成装置。
- 前記第1転写電源装置は、すべての前記転写ローラーにそれぞれ電位を付与する、請求項1に記載の画像形成装置。
- 前記複数の転写ローラーのうち、前記被転写体の進行方向において最も下流側に位置する前記転写ローラーに電位を付与する第2転写電源装置を更に備え、
前記第1転写電源装置は、前記被転写体の進行方向に対して、前記第2転写電源装置から電位が付与される前記転写ローラーよりも上流側に位置するすべての前記転写ローラーへ電位を付与する、請求項1に記載の画像形成装置。 - 前記第2転写電源装置から電位が付与される前記転写ローラーと前記第2転写電源装置との間に直列に接続される負荷抵抗を更に備える、請求項7に記載の画像形成装置。
- 前記転写ローラーは、弾性ローラーを含む、請求項1に記載の画像形成装置。
- 前記弾性ローラーは、導電性粒子を含む、請求項9に記載の画像形成装置。
- 前記導電性粒子は、カーボンを含む、請求項10に記載の画像形成装置。
- 前記転写ローラーの回転軸の位置は、対向する前記感光体ドラムの回転軸の位置から、前記被転写体の進行方向の上流側又は下流側にずれるように配置される、請求項1に記載の画像形成装置。
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