JP2008145827A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent staining of the rear surface of a succeeding transfer material conveyed to a transfer nip portion, when a patch image is formed in the paper gap between transfer materials. <P>SOLUTION: The image forming apparatus has: an image carrier which carries a toner image; a transfer member which transfers the toner image formed on the image carrier to the transfer material; a power supply for transfer which applies a voltage to the transfer member; a separation charge-eliminating member which is arranged at the downstream of the transfer member in the conveying direction of the transfer material; a power supply for separation charge elimination which applies a voltage having properties opposite to those of the voltage applied to the transfer member, to the separation charge-eliminating member; a density detecting means which detects the density of the patch image formed on the image carrier; and a shield member which freely shields or opens at least the part corresponding to the patch image formed on the image carrier, of the paper passing width of the transfer material in the separation charge-eliminating member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a copying machine, a printer, a facsimile, and an image forming apparatus using an electrophotographic system having these functions, and in particular, a toner image carried on the surface of a toner image carrier or the like is used as a transfer material by a transfer member. The present invention relates to an image forming apparatus for transferring, or a color image forming apparatus for superimposing a plurality of color toner images formed on an intermediate transfer body and transferring them to a transfer material by a transfer member.

  An image forming apparatus such as a laser printer includes a photoconductive drum and a transfer roller disposed to face the photoconductive drum. A toner image based on image data is carried on the photosensitive drum, and the toner image carried on the photosensitive drum passes between the photosensitive drum and the transfer roller by applying a transfer bias voltage to the transfer roller. Is transferred to a transfer material. In this type of image forming apparatus, the transfer material may stick to the outer peripheral surface of the transfer roller.

  As an example of an intermediate transfer type color image forming apparatus, a developing device for each color component of yellow, magenta, cyan, and black is provided around an image carrier such as a photosensitive drum, and an intermediate with respect to the image carrier. The transfer body is placed opposite to each other, and the unfixed toner image of each color component formed on the image carrier for each color component image forming cycle of the image carrier is firstly transferred to the intermediate transfer body in sequence, and then superimposed on the intermediate transfer body. In some cases, each color toner image is secondarily transferred to a transfer material such as paper to form a desired color image on the transfer material.

  As a secondary transfer device for transferring each color toner image on the intermediate transfer member to the transfer material, for example, the transfer roller is pressed against the surface side (the surface side on which the toner image is transferred) of the intermediate transfer member supported by the backup roller. The intermediate transfer member and the transfer roller sandwich and convey the transfer material, and a transfer bias voltage is applied to one or both of the backup roller and the transfer roller to transfer the toner image on the intermediate transfer member to the transfer material. In this case, a batch transfer is used. This type of color image forming apparatus is also provided with a separating means for preventing the transfer material from sticking to the transfer roller during the secondary transfer.

  As the separation charge eliminating member, a sawtooth shaped charge removal needle or a corona discharger is used.

  Generally, in an electrophotographic image forming apparatus, the image density is likely to fluctuate due to characteristic fluctuations due to the number of images formed on the photosensitive drum and the developing device. Therefore, density control is performed prior to normal image formation. In particular, since a color image forming apparatus is required to maintain a delicate color balance, more accurate density control is required for each of Y, M, C, and K.

  In recent years, image forming apparatuses such as copiers, printers, facsimiles, and multifunction machines having these functions have become increasingly demanded for high image quality in the transfer process due to the use of polymerized toner and small particle size toner. Yes. The speed of image forming apparatuses is also increasing.

  An image that forms a patch image on an image carrier and detects the density thereof, thereby controlling the image forming conditions such as a charging potential, an exposure potential, and a developing bias potential to output a stable image. Forming devices are conventionally known.

  However, since such control takes time, if the density control time is provided in the middle of the image forming processing job, the productivity decreases.

  As a countermeasure, it is conceivable to control the image density by forming a patch image between images (between sheets) during the image forming process.

  However, when a patch image is formed between papers without a transfer material, the patch image is transferred to a transfer roller, which causes a problem that the back surface of the subsequent transfer material is stained.

  As countermeasures, there is a technique of separating the transfer roller from the image carrier or applying a transfer reverse bias voltage (a bias voltage having a reverse characteristic to the toner charge) at the timing when the patch image arrives.

In the image forming apparatus disclosed in Patent Document 1, if the patch image on the photosensitive drum is transferred to the intermediate transfer belt at the primary transfer unit, the density of the patch image cannot be detected with high accuracy, so the patch image passes through the primary transfer unit. In this case, the intermediate transfer belt is separated from the photosensitive drum so that the patch image is not transferred to the intermediate transfer belt.
JP 2001-5237 A

  The above-described conventional image density control still has the following problems.

  (1) In a high-speed image forming apparatus, it is not possible to secure the time required for pressure bonding after separating the transfer member.

  (2) When there is a separation static elimination member to which a bias voltage having a reverse characteristic to that of the transfer roller is applied adjacent to the transfer member, even if a reverse characteristic bias voltage is applied to the transfer member, the discharge for the separation static elimination Disturbed by (AC + DC voltage), transfer discharge cannot be performed.

  (3) Although the reverse transfer bias voltage can be applied by turning off the separation neutralization output between the transfer material sheets, in a high-speed image forming apparatus, there is no time to turn off / on the separation output between sheets. . That is, the transfer member is a high-resistance elastic body, and it takes time until the output from the high-voltage power source is stabilized. The output of a separate static elimination needle that discharges adjacently is also affected by this. In particular, in the case of AC voltage, it takes several hundreds of milliseconds to stabilize.

  The present invention has been made in order to solve the above technical problem, and the load on the discharge at the time of transfer is reduced by suppressing the separation and neutralization output in the patch image between the sheets of the transfer material. An object of the present invention is to provide an image forming apparatus that prevents the back surface of the subsequent transfer material conveyed by the nip portion from being stained.

  An image forming apparatus of the present invention that achieves the above object includes an image carrier that carries a toner image, a transfer member that transfers the toner image formed on the image carrier to a transfer material, and a transfer member A transfer power source for applying a voltage; a separation charge eliminating member disposed downstream of the transfer member in a transfer material conveyance direction; and a separation applying a voltage opposite to the voltage applied to the transfer member to the separation charge removal member The patch image formed on at least the image carrier out of the power supply for static elimination, the density detection means for detecting the density of the patch image formed on the image carrier, and the sheet passing width of the transfer material of the separation static elimination member A shielding member that shields or opens a portion corresponding to the image forming apparatus.

  The following effects can be obtained by the image forming apparatus of the present invention.

  Between the sheets of transfer material, the discharge by the separation and neutralization member in the patch image portion is suppressed, and the discharge load of the transfer increases locally. Accordingly, the transfer discharge at the patch image position is suppressed, and it becomes difficult to draw the patch image between the sheets to the transfer roller side. Therefore, the separation charge removal output in the patch image is suppressed between the transfer material sheets, and the transfer nip portion is conveyed. Back surface contamination on the subsequent transfer material is prevented.

  The present invention will be described using embodiments, but the present invention is not limited to the embodiments described below.

  FIG. 1 is a cross-sectional view showing a main part of an image forming apparatus A according to an embodiment of the present invention.

  This image forming apparatus A is called a tandem type color image forming apparatus, and a plurality of sets of image forming means 20Y, 20M, 20C, 20K, a second image carrier (intermediate transfer belt) 1, a primary transfer roller 25Y. , 25M, 25C, 25K, an intermediate transfer unit composed of a transfer member (secondary transfer roller) 3, a fixing device 16, and a paper feeding device (not shown).

  The document placed on the document table is scanned and exposed by the optical system of the document image scanning exposure apparatus of the image reading apparatus, and read by the line image sensor. The analog signal photoelectrically converted by the line image sensor is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in the image processing unit, and then input to the exposure means 23Y, 23M, 23C, and 23K. .

  The image forming unit 20Y for forming a yellow (Y) color image includes a charging unit 22Y, an exposing unit 23Y, a developing unit 24Y, and a cleaning unit 26Y disposed around the first image carrier (photoconductor) 21Y. .

  The image forming unit 20M that forms a magenta (M) color image includes a first image carrier (photoconductor) 21M, a charging unit 22M, an exposure unit 23M, a developing unit 24M, and a cleaning unit 26M.

  The image forming unit 20C for forming a cyan (C) color image includes a first image carrier (photoconductor) 21C, a charging unit 22C, an exposure unit 23C, a developing unit 24C, and a cleaning unit 26C.

  The image forming unit 20K that forms a black (K) image includes a first image carrier (photoconductor) 21K, a charging unit 22K, an exposure unit 23K, a developing unit 24K, and a cleaning unit 26K.

  The charging unit 22Y and the exposure unit 23Y, the charging unit 22M and the exposure unit 23M, the charging unit 22C and the exposure unit 23C, and the charging unit 22K and the exposure unit 23K constitute a latent image forming unit.

  As the photoconductors 21Y, 21M, 21C, and 21K, known ones such as an OPC photoconductor and an aSi photoconductor are used, but an OPC photoconductor is preferable, and in particular, a negatively charged OPC photoconductor is preferable. In this case, a negatively chargeable OPC photoreceptor is used.

  As the charging means 22Y, 22M, 22C, and 22K, corona discharge means such as scorotron and corotron are used, and scorotron discharge means is preferably used.

  As the exposure means 23Y, 23M, 23C, and 23K, light emitting elements that emit light according to image data, such as lasers and LED arrays, are used.

  The intermediate transfer belt 1 is semiconductive and is wound and circulated by a transfer facing roller 2, a supporting roller 2B, a driving roller 2C, a driven roller 2D, a tension roller 2E, a cleaning roller 2F, and a roller 2G facing the sensor PS. It is supported movably. In the present embodiment, the intermediate transfer belt 1 is supported in a planar shape between the driving roller 2C and the driven roller 2D.

  The toner images of the respective colors formed by the image forming units 20Y, 20M, 20C, and 20K are sequentially transferred (primary transfer) by the primary transfer rollers 25Y, 25M, 25C, and 25K onto the rotating intermediate transfer belt 1 to be combined. A toner image T of the color image thus formed is formed on the intermediate transfer belt 1. The toner image T is transferred to the transfer material P by the secondary transfer roller 3.

  In the color image forming apparatus shown in FIG. 1, a patch image is performed by measuring reflected light by an image density sensor 27 having a light emitting element and a light receiving element.

  These image density sensors 27 are installed on the most downstream side of the primary transfer portion formed on the intermediate transfer belt 1, and the density of the patch image formed on the intermediate transfer belt 1 is measured. The image density is controlled by changing the image forming conditions such as the charging potential of the photoconductors 21Y, 21M, 21C, and 21K, the laser exposure potential, and the developing bias potential by the control unit based on the measurement result.

  The transfer material P accommodated in the paper feeding cassette of the paper feeding device is fed by a paper feeding means (first paper feeding unit) (not shown), and feeds a paper feeding roller 12 and a registration roller (second paper feeding unit) 13. Then, the secondary transfer roller 3 and the transfer counter roller 2 of the secondary transfer unit are conveyed to the transfer nip N where they abut via the intermediate transfer body 1, and the toner image is transferred onto the transfer material P ( Secondary transfer).

  Alternatively, the transfer material P sent out from the manual paper feed unit is conveyed to the transfer nip N through the paper feed roller 11 and the registration roller 13.

  The transfer material P onto which the color image has been transferred is transported by the transport belt 15, heat and pressure are applied in the fixing device 16, and the intermediate transfer body 1 separated by the curvature separation and separation claw 14 is cleaned. Residual toner is removed by the roller 2F.

  FIG. 2 is a cross-sectional view showing an image forming unit 40 according to another embodiment of the image forming apparatus A.

  Around the image carrier (photosensitive member) 41, a charging unit 42, an exposing unit 43, a developing unit 44, a transfer roller 45, a separation claw 46, and a cleaning unit 47 are arranged in the order of the image forming process.

  The transfer roller 45 is formed of a conductive elastic layer formed on the surface of the rotating shaft. A transfer voltage is applied to the transfer roller 45 by a transfer power supply 45E. The photoconductor 41 facing the transfer roller 45 is grounded.

  A separation static elimination member 48 is disposed on the downstream side in the transfer material conveyance direction of the transfer nip N where the transfer roller 45 and the photoreceptor 41 are in pressure contact. A voltage having a characteristic opposite to that of the transfer voltage applied to the transfer roller 45 by the separation / neutralization power source 48E is applied to the separation / neutralization member 48.

  The density control of the patch image is performed by measuring the reflected light by the density detecting means 49 having a light emitting element and a light receiving element.

  The transfer power supply 45E transfers the residual toner attached to the transfer roller 45 to the photoconductor 41 by applying a reverse bias. The photoreceptor 41 carrying the residual toner is cleaned by a cleaning unit 47.

  FIG. 3 is a perspective view of the secondary transfer unit and the separation charge eliminating member. FIG. 4 is a side view of the vicinity of the secondary transfer portion and the transfer roller.

  A shielding member 5 is slidably disposed on the downstream side in the transfer material conveyance direction of the separation static elimination needle 4. The shielding member 5 shields or opens a portion corresponding to the patch image Pa on the intermediate transfer belt 1 corresponding to the space between the transfer materials conveyed to the transfer nip portion N in the longitudinal direction of the separation static elimination needle 4.

  A transfer voltage is applied to the secondary transfer roller 3 constituting the secondary transfer means by a transfer power source 3E. The transfer facing roller 2 that faces the secondary transfer roller 3 via the intermediate transfer belt 1 is grounded.

The intermediate transfer belt 1 is made of a resin such as polyimide, polycarbonate, polyester, or various rubbers containing a conductive agent, and is adjusted to have a volume resistivity of 10 ^{5 to} 10 ¹² Ω · cm.

  The secondary transfer roller 3 plays a role of transferring the image formed on the intermediate transfer belt 1 as the second image carrier to the transfer material P, and discharges with a reverse characteristic to the toner (for example, a DC constant current of 100 μA). Application), the toner on the intermediate transfer belt 1 is attracted.

  When a transfer bias is applied to the transfer facing roller 2 disposed inside the intermediate transfer belt 1 facing the secondary transfer roller 3, transfer is performed by applying a repulsive force to the toner by applying a bias voltage having the same polarity as the toner. Transfer to material P.

The secondary transfer roller 3 is made by coating the surface of an elastic member such as acrylonitrile / butadiene rubber (NBR) or urethane rubber with a fluororesin, or by coating the surface of an elastic member with a fluorine or nylon tube. Is used. The secondary transfer roller 3 is controlled to have a volume resistance of 10 ³ Ω to 10 ¹² Ω by introducing a conductive agent. The secondary transfer roller 3 is rotated by driving means (not shown).

  A non-contact type separation neutralization member (separation neutralization needle) 4 is disposed on the downstream side in the transfer material conveyance direction of the transfer nip N where the secondary transfer roller 3 and the transfer counter roller 2 are in pressure contact. The separation static elimination needle 4 includes a sawtooth-shaped conductive thin plate, a plurality of conductive needle-like electrodes arranged in parallel, or one having at least one conductive wire stretched, and corona discharge by applying a voltage. Is done.

  A voltage having a reverse characteristic to the transfer voltage applied to the secondary transfer roller 3 is applied to the separation / neutralization needle 4 by the separation / neutralization power source 4E. For example, when transferring toner having a negative charge, a positive transfer voltage is applied to the secondary transfer roller 3, and a negative charge removal voltage is applied to the separation charge removal needle 4.

  An AC + DC bias voltage having characteristics opposite to those of the transfer bias is applied to the separation / neutralization needle 4. For example, a bias voltage of AC effective current 60 μA + DC effective current −30 μA is applied.

  The separation / neutralization needle 4 has a role of preventing generation of toner dust in an unfixed image held on the transfer material P being conveyed by separating and holding an appropriate charge on the transfer material P.

  The secondary transfer output and the output of the separation static elimination needle 4 have a reverse characteristic and are discharged in a close arrangement, and thus influence each other. It is easier to discharge when a discharge with reverse characteristics occurs nearby than when discharging with only one. Further, it is known that these are discharged by a constant current, and when the load with respect to the discharge in the longitudinal direction changes, the current easily flows to a place where the load is smaller.

  In such a background, for example, when a 10 mm × 20 mm rectangular patch image Pa is formed, a synergistic effect of transfer and separation discharge at the position where the patch image Pa is formed (for example, near the center in the longitudinal direction). By invalidating the effect, it is difficult to draw the patch image Pa on the intermediate transfer belt 1 to the secondary transfer roller 3 side.

  As a method for this, in the present invention, the tip of the separation static elimination needle 4 corresponding to the formation position of the patch image Pa is shielded by the shielding member 5. By doing so, the transfer discharge current easily flows except where the shielding member 5 is present, and the discharge at the position where the patch image Pa is formed on the shielding member 5 is weakened. Therefore, the patch image Pa is not transferred to the secondary transfer roller 3. Thereby, the back surface of the subsequent transfer material P is not stained.

  The shielding member 5 holds the separation / neutralization needle 4 in an open state when the paper is passed, so that the discharge of charge removal is uniform in the longitudinal direction, and the exchange of discharge for transfer and separation is also performed uniformly.

  FIG. 5 is a front view of the vicinity of the secondary transfer portion and the transfer roller.

  The shielding member 5 is formed by integrally forming a shielding part 5A, an upper actuator part 5B, a rotating shaft part 5C, and a lower tongue part 5D. The spring 6 hung on the tip of the tongue 5D urges the shielding member 5 to swing around the rotating shaft 5C.

  FIG. 5A shows a state where the shielding member 5 shields the distal end portion of the separation static elimination needle 4. The shielding portion 5A of the shielding member 5 is biased by the spring 6 to shield the distal end portion of the separation static elimination needle 4 except when image transfer and transfer material separation are performed. That is, the shielding member 5 shields a portion corresponding to the patch image Pa of the separation static elimination needle 4, for example, the vicinity of the central portion of the distal end portion of the separation static elimination needle 4.

  FIG. 5B shows a state in which the shielding member 5 opens the distal end portion of the separation static elimination needle 4. The shielding part 5A of the shielding member 5 is in contact with the passage of the transfer material P when the image is transferred and the transfer material is separated. Thus, the rotary shaft portion 5C is tilted about the rotation center to release the shielding of the tip portion of the separation static elimination needle 4, and normal transfer and separation performance can be obtained.

  FIG. 6 is a diagram showing a current distribution in the longitudinal direction of the separation static elimination needle 4.

  Since the central portion of the separation static elimination needle 4 is shielded by the shielding member 5 and the discharge of the separation static elimination needle 4 is suppressed, the load on the transfer increases, and the discharge of the separation static elimination needle 4 at the corresponding position of the patch image Pa is invalidated. To. That is, although the total current of the separation static elimination needle 4 does not change, the current distribution of the separation static elimination needle 4 changes.

  FIG. 7 is a front view of the vicinity of the secondary transfer portion and the transfer roller. FIG. 7A shows a state where the shielding member 5 shields the distal end portion of the separation static elimination needle 4, and FIG. A state in which the shielding member 5 opens the distal end portion of the separation static elimination needle 4 is shown.

  In addition, about the code | symbol used in drawing, the same code | symbol is attached | subjected to the part which has the same function as FIG. Further, differences from FIG. 4 will be described.

  As shown in FIG. 5, the operation of the shielding member 5 can be automatically performed in conjunction with the transfer of the transfer material P. However, in the case of a thin transfer material P having a weak waist, the shielding member 5 is operated. When abutting against the shielding portion 5A, there is a possibility that the leading end portion of the transfer material P is deformed and a transfer material conveyance failure occurs. As a countermeasure, a solenoid is operated when the transfer material P passes through the transfer nip N based on a sensor (for example, a registration sensor) PS for detecting the sheet passing state of the transfer material P or an image formation trigger. Thus, the shielding member 5 may be made swingable, and the separation static elimination needle 4 may be configured to be openable and closable.

  The shielding member 5 is formed by integrally forming a shielding portion 5A, a rotating shaft portion 5C, and a lower tongue portion 5D. The spring 6 hung on the tip of the tongue 5D biases the shielding member 5 and swings about the rotation shaft 5C as the center of rotation, thereby shielding the tip of the separation static elimination needle 4. The solenoid SOL connected to the tip of the tongue 5D swings the shielding member 5 to freely open the tip of the separation charge eliminating needle 4.

  FIG. 8 is a block diagram of a control means for controlling the driving of the separation static elimination needle 4 and the shielding member 5.

  Toner images of the respective colors are formed on the photoreceptors 21Y, 21M, 21C, and 21K by the image forming units 20Y, 20M, 20C, and 20K. The patch image Pa superimposed on the rotating intermediate transfer belt 1 is formed by the control means 9 so as to be formed at a position corresponding to the space between the sheets of the transfer material P conveyed from the registration roller 13 in the secondary transfer portion. Be controlled.

  The shielding member 5 that shields the vicinity of the central portion in the longitudinal direction of the separation static elimination needle 4 disposed on the downstream side in the transfer material conveyance direction of the secondary transfer portion is driven by the solenoid SOL, and the patch image Pa passes through the secondary transfer portion. When the transfer material P passes, the separation charge-eliminating needle 4 is shielded to prevent the transfer to the secondary transfer roller 3, and when the transfer material P passes, the separation charge-elimination needle 4 is opened.

  By the above control, the load for the transfer discharge is made by changing the method of the discharge for separation at a position in the longitudinal direction between the sheets, for example, at a position near the center of the separation static elimination needle 4. In the high-speed image forming apparatus in which the patch image Pa is formed between the papers, it is possible to prevent the back surface of the subsequent transfer material P from being stained.

FIG. 3 is a cross-sectional view showing a main part of the image forming apparatus according to the embodiment of the present invention. Sectional drawing which shows the image forming means of other embodiment of an image forming apparatus. The perspective view of a secondary transfer part and a separation static elimination member. FIG. 4 is a side view of the vicinity of a secondary transfer portion and a transfer roller. The front view of the secondary transfer part and the vicinity of the transfer roller. The figure which shows the electric current distribution of the longitudinal direction of a separation static elimination needle. The front view of the secondary transfer part and the vicinity of the transfer roller. The block diagram of the control means which controls the drive of a separation static elimination needle and a shielding member.

Explanation of symbols

1 Second image carrier (intermediate transfer belt)
2 Transfer opposing roller 3 Transfer member (secondary transfer roller)
3E Power supply for transfer 4 Separation static elimination member (separation static elimination needle)
4E Power supply for separation and neutralization 5 Shielding member 5A Shielding part 5B Actuator part 6 Spring 9 Control means 13 Registration roller (second paper feeding part)
20Y, 20M, 20C, 20K Image forming means 21Y, 21M, 21C, 21K First image carrier (photoconductor)
25Y, 25M, 25C, 25K Primary transfer roller 27 Image density sensor 40 Image forming means 41 Image carrier (photosensitive member)
45 Transfer roller 45E Power supply for transfer 48 Separation neutralization member 48E Power supply for separation neutralization 49 Concentration detection means (density sensor)
A Image forming device N Transfer nip P Transfer material Pa Patch image SOL Solenoid

Claims (8)

An image carrier for carrying a toner image;
A transfer member for transferring the toner image formed on the image carrier to a transfer material;
A transfer power source for applying a voltage to the transfer member;
A separation static elimination member disposed downstream of the transfer member in the transfer material conveyance direction;
A power supply for separation and neutralization that applies a voltage opposite to the voltage applied to the transfer member to the separation and neutralization member;
Density detecting means for detecting the density of the patch image formed on the image carrier;
A shielding member that shields or opens at least a portion corresponding to the patch image formed on the image carrier among the sheet passing width of the transfer material of the separation charge eliminating member;
An image forming apparatus comprising: The shielding member keeps the portion corresponding to the patch image of the separation charge eliminating member open when transferring the toner image and separating the transfer material from the transfer member; otherwise, the shielding member The image forming apparatus according to claim 1, wherein a portion corresponding to the patch image of the separation charge eliminating member is shielded. The shielding member includes a control unit that controls the portion corresponding to the patch image of the separation charge eliminating member to be in an open state in synchronization with the transfer material entering the transfer nip portion of the transfer member. The image forming apparatus according to claim 1, wherein: The shielding member is capable of rotating the shielding portion that opens and closes the separation static elimination member, an actuator portion that can contact the leading end portion of the transfer material conveyed to the transfer nip portion, and the shielding portion and the actuator portion. The image forming apparatus according to claim 1, further comprising a rotating shaft portion that supports the image forming apparatus. The shielding member includes a shielding portion that shields the separation charge eliminating member, and when the transfer material is passed through the transfer nip portion of the transfer member, the shielding portion is rotated by a driving unit to rotate the shielding portion. 5. The image forming apparatus according to claim 1, wherein a portion corresponding to the patch image of the separation static elimination member is held in an open state. 6. The image forming apparatus according to claim 1, wherein the separation and neutralization member is a sawtooth-shaped separation and neutralization needle. The image forming apparatus according to claim 1, wherein the image carrier is a photosensitive member or an intermediate transfer member. The image forming apparatus according to claim 1, wherein the transfer member has a roller shape or a belt shape.

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