JP2006259367A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image forming apparatus which is long-lived and maintains stable performance by preventing faulty cleaning or an image defect caused by an effect that a little toner which passes through a cleaning means in a brush cleaning system is retained and accumulated. <P>SOLUTION: Two brush rolls 50A and 50B are provided in a conveying belt cleaner 48 for removing toner on a conveying belt 42 (secondary transfer part), and bias having a positive polarity is applied to the brush roll 50A arranged on an upstream side in a conveying belt rotating direction, and bias having a negative polarity is applied to the brush roll 50B arranged on a downstream side. Two brush rolls 58A and 58B are provided in an intermediate transfer belt cleaner 56 for removing toner on an intermediate transfer belt 22, and bias having a negative polarity is applied to the brush roll 58A arranged on an upstream side in an intermediate transfer belt rotating direction, and bias having a positive polarity is applied to the brush roll 58B arranged on a downstream side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and more specifically, an intermediate transfer member that primarily transfers a toner image formed on a photosensitive member to an intermediate transfer member, and further secondary-transfers the toner image on the intermediate transfer member to a recording medium. The present invention relates to a type image forming apparatus.

  An intermediate transfer member type image forming apparatus that primarily transfers a toner image formed on a photosensitive member to an intermediate transfer member such as an intermediate transfer belt by electrophotographic technology, and further transfers the toner image on the intermediate transfer member to a sheet. Then, it is necessary to clean transfer residual toner and the like remaining on the intermediate transfer member after transfer onto the paper.

  As a cleaning means for cleaning the residual toner from the intermediate transfer member, a blade cleaning method using a blade or a brush cleaning (electrostatic cleaning) method using a conductive brush roll has been conventionally employed.

  However, in the case of a blade, there are problems such as sudden cleaning failure due to edge chipping, paper dust, foreign matter, or the like, or deterioration in cleaning performance due to blade wear over time and wear of the cleaning object.

  In contrast, brush rolls are less susceptible to sudden failures such as blades, and because they have less wear, they have the advantage of maintaining cleaning performance over time. It is conceivable that the intermediate transfer member using the blade, the secondary transfer portion, and the photosensitive member cleaning means are all brush cleaners.

  However, in the brush cleaning method, the sealing performance is lower than that of the blade, and the toner to be cleaned may slip through the cleaner slightly. For this reason, if the slip-through toner is transferred to another functional member and circulated and accumulated over time, an image defect or the like is generated and reliability is lowered.

In this regard, two brush rolls (conductive fur brushes) that apply biases of different polarities in the cleaning of the intermediate transfer member are used, and the transfer is performed by arranging the positive electrode and the negative electrode in this order from the upstream side in the rotation direction of the intermediate transfer member. Techniques have been proposed for collecting toner mixed with both poles such as residual toner (see, for example, Patent Document 1). In addition, a technique has been proposed in which a negative polarity bias is applied to a charging roll provided on the upstream side of the brush roll to charge the toner to a negative polarity, and then cleaning is performed with a brush roll to which a positive polarity bias is applied ( For example, see Patent Document 2).
JP 2002-229344 A JP 2001-201949 A

  However, in the technique of the above-mentioned Patent Document 1, when the transfer rate decreases under a high humidity environment or the like and the amount of toner entering the intermediate transfer body cleaner increases, a toner that has slightly passed through the cleaner is generated. The polarity tends to be negative and is not collected at the primary transfer portion between the photosensitive member and the intermediate transfer member, and thus appears as an image quality defect.

  On the other hand, in the technique of Patent Document 2, since the polarity becomes positive when the residual toner passes through the intermediate transfer body cleaner, for example, in the primary transfer portion, the residual toner charged to the positive polarity is used as the cleaner of the photoconductor. It can also be collected. However, in this case, since there is a single brush roll, the amount of toner passing through increases and the amount of toner that enters the photoreceptor cleaner increases, resulting in poor cleaning on the photoreceptor.

  In consideration of the above facts, the present invention can prevent cleaning defects and image defects caused by the accumulation and accumulation of toner that has slightly passed through the cleaning means in the brush cleaning method, and can maintain a long life and stable performance. It is an object of the present invention to provide an image forming apparatus that can be used.

  In order to achieve the above object, the invention according to claim 1 is an intermediate transfer in which a toner image having a predetermined polarity formed on a rotating photoreceptor is primarily transferred to the surface and conveyed to a secondary transfer portion. And a secondary transfer member for secondary transfer of the toner image from the intermediate transfer body to the recording medium at the secondary transfer portion while rotating in the same direction as the transport direction, and remaining on the surface of the intermediate transfer body In the image forming apparatus, comprising: an intermediate transfer body cleaning unit that removes residual toner; and a secondary transfer member cleaning unit that removes toner adhering to the surface of the secondary transfer member. A first intermediate transfer body brush roll that is applied with a bias having the same polarity as the toner image and rotationally contacts the surface of the intermediate transfer body; A second intermediate transfer member brush roll that is provided downstream in the direction and that is applied with a bias having a polarity opposite to that of the toner image and is in rotational contact with the surface of the intermediate transfer member, and the secondary transfer member The cleaning means includes a first secondary transfer member brush roll, which is applied with a bias having a polarity opposite to that of the toner image and is in rotational contact with the surface of the secondary transfer member, and the first secondary transfer member brush roll. A second secondary transfer member brush roll which is provided on the downstream side in the rotational movement direction and which is in rotation contact with the surface of the secondary transfer member by applying a bias having the same polarity as the toner image. It is said.

  In the first aspect of the present invention, the first secondary transfer member brush roll is provided with two secondary transfer member brush rolls in the secondary transfer member cleaning means, and is arranged on the upstream side in the rotational movement direction of the secondary transfer member. In addition, by applying a bias having a polarity opposite to that of the toner image (for example, positive electrode) and applying a bias having the same polarity as the toner image (for example, negative electrode) to the second secondary transfer member brush roll disposed on the downstream side, The toner that has slightly passed through the secondary transfer member cleaning means has the same polarity (for example, negative electrode) as that at the time of formation.

  Therefore, when a transfer bias in the direction of transferring the toner image from the intermediate transfer member to the recording medium is applied to the secondary transfer portion, the slipping toner does not electrostatically transfer to the recording medium. By applying a bias having a polarity opposite to that at the time of transfer in the inter-image, the slip-through toner is transferred to the intermediate transfer member side.

  Further, the intermediate transfer member cleaning unit is provided with two intermediate transfer member brush rolls, and the first intermediate transfer member brush roll disposed on the upstream side in the toner image transport direction (moving direction to the intermediate transfer member) By applying a bias having the same polarity (for example, negative electrode) and applying a bias having a polarity opposite to that of the toner image (for example, positive electrode) to the second intermediate transfer member brush roll disposed on the downstream side, it is conveyed from the secondary transfer unit. The slipped toner that has entered the intermediate transfer member cleaning means is recharged to the same polarity (for example, negative electrode) as that formed by the first intermediate transfer member brush roll, while being intermediated by the mechanical scraping force of the brush roll. The adhesion with the transfer member is weakened, and it is reliably recovered by the second intermediate transfer member brush roll to which a bias having a polarity opposite to that at the time of formation is applied.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus further includes a photosensitive member cleaning unit that removes residual toner remaining on the surface of the photosensitive member, and the photosensitive member cleaning unit includes the toner image. A first photosensitive brush roll that is rotated and brought into contact with the surface of the photosensitive member by applying a bias having a polarity opposite to that of the first photosensitive member, and the toner image is provided downstream of the first photosensitive brush roll in the rotational direction. And a second photosensitive brush roll that is rotationally contacted with the surface of the photosensitive member by applying a bias having the same polarity as that of the first photosensitive member.

  In the second aspect of the present invention, when the toner is slightly slipped by the intermediate transfer member cleaning unit, the slipping toner has a polarity (for example, positive electrode) opposite to that at the time of formation. Therefore, when the slipping toner is transported and returned to the primary transfer portion, and the transfer bias of the same polarity (direction in which the toner image is transferred from the photosensitive member to the intermediate transfer member) is applied to the primary transfer portion, To metastasize.

  The photosensitive member cleaning means is provided with two photosensitive brush rolls, and a bias having a polarity (for example, positive polarity) opposite to that of the toner image is applied to the first photosensitive brush roll disposed on the upstream side in the rotation direction of the photosensitive member. By applying a bias having the same polarity as the toner image (for example, negative electrode) to the second photosensitive brush roll disposed on the downstream side, the toner transferred onto the photosensitive member is formed by the first photosensitive brush roll. The second photosensitive member to which a bias having the same polarity as that at the time of formation is applied while the adhesive force to the photosensitive member is weakened by the mechanical scraping force of the brush roll while being recharged to the opposite polarity (for example, positive electrode). It is reliably collected by the brush roll.

  Further, even if the toner is slightly slipped by this photosensitive member cleaning means, the slipping toner has a polarity (for example, positive electrode) opposite to that at the time of formation, so that, for example, in the developing unit provided on the downstream side in the rotation direction of the photosensitive member. Simultaneous development recovery is possible.

  Since the image forming apparatus of the present invention has the above-described configuration, it is possible to prevent cleaning defects and image defects due to retention and accumulation of toner that has slightly passed through the cleaning unit, and it is possible to maintain a long life and stable performance.

  An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, an image forming apparatus 10 according to the present exemplary embodiment is provided with a photoconductor 12 that is driven to rotate in the direction of arrow A (rightward rotation direction) in the drawing at the approximate center. Above the photoconductor 12, a charging device 14 having a charging roll for charging the surface of the photoconductor 12 is disposed, and further, the surface of the photoconductor 12 charged by the charging device 14 is positioned in the upper part of the device. An exposure device 16 is provided for forming an electrostatic latent image by irradiating the laser beam L with the laser beam L.

  On the right side of the photoreceptor 12, a rotary developing device 18 that develops the electrostatic latent image formed on the photoreceptor 12 into a toner image is disposed adjacently. The rotary developing device 18 includes developing units 20Y, 20M, 20C, and 20K that respectively form toner images of four colors of yellow, yellow, magenta, cyan, and black.

  Below the photoreceptor 12, an intermediate transfer belt 22 to which a toner image visualized by the rotary developing device 18 is transferred is provided, and a primary transfer roll 24 is disposed opposite to the intermediate transfer belt 22 therebetween. . The contact portion between the photoreceptor 12 and the intermediate transfer belt 22 is a primary transfer portion T1, and a primary transfer bias having a positive polarity is applied to the primary transfer roll 24.

  On the left side of the photoconductor 12, a photoconductor cleaner 26 is disposed adjacently to remove residual toner remaining on the photoconductor 12 after the primary transfer. The photoconductor cleaner 26 includes two brush rolls 28A and 28B that are pressed against the surface of the photoconductor 12 and are driven to rotate in a direction opposite to the rotation direction of the photoconductor 12 to scrape off transfer residual toner. Two recovery rolls 30A and 30B for recovering toner from each of the brush rolls 28A and 28B, and two scrapers 32A and 32B for scraping off toner from each of the recovery rolls 30A and 30B are provided.

  The intermediate transfer belt 22 is wound around a drive roll 34, a secondary transfer backup roll 36, and a brush backup roll 38, and rotates in the same direction in synchronization with the rotation of the photosensitive member 12. As a result, the intermediate transfer belt 22 is primarily transferred by the primary transfer roll 24 at the primary transfer portion T1 so that the toner images on the photoreceptor 12 are superposed in the order of yellow, magenta, cyan, and black, and the primary transferred toner image is transferred. It is transported toward the following secondary transfer portion T2 (secondary transfer roll 44).

  A conveyance belt 42 is provided below the intermediate transfer belt 22 with a conveyance path 40 interposed therebetween. The conveyance belt 42 is wound around a secondary transfer roll 44 and a drive roll 46 that are arranged to face the secondary transfer backup roll 36, and rotates in the same direction in synchronization with the rotation of the intermediate transfer belt 22. A space between the intermediate transfer belt 22 and the conveyance belt 42 is a secondary transfer portion T2, and a secondary transfer bias having a negative polarity is applied to the secondary transfer roll 44. The secondary transfer roll 44 secondarily transfers the toner image primarily transferred to the intermediate transfer belt 22 onto the paper P with the aid of the secondary transfer backup roll 36 at the secondary transfer portion T2. The secondary transfer roll 44 is separated from the intermediate transfer belt 22 while the intermediate transfer belt 22 rotates three times, that is, while the toner images of three colors of yellow, magenta, and cyan are conveyed. When the image is transferred, it substantially contacts the intermediate transfer belt 22.

  A transport belt cleaner (secondary transfer section cleaner) 48 that removes toner adhering to the transport belt 42 from the intermediate transfer belt 22 is disposed adjacent to the left side of the secondary transfer roll 44 that rotatably supports the transport belt 42. Yes. Similarly to the photosensitive member cleaner 26 described above, the conveyance belt cleaner 48 is in contact with the surface of the conveyance belt 42 and is driven to rotate in a direction opposite to the rotation direction of the conveyance belt 42 to rub off adhering toner. 50B, two recovery rolls 52A and 52B for recovering toner from each of the brush rolls 50A and 50B, and two scrapers 54A and 54B for scraping off toner from each of the recovery rolls 52A and 52B.

  On the right side of the brush backup roll 38 that rotatably supports the intermediate transfer belt 22, an intermediate transfer belt cleaner 56 that removes transfer residual toner remaining on the intermediate transfer belt 22 after the secondary transfer is provided so as to be able to contact and separate. . The intermediate transfer belt cleaner 56 is separated from the intermediate transfer belt 22 while the intermediate transfer belt 22 conveys the toner image, and contacts the intermediate transfer belt 22 during cleaning. Similarly to the photoconductor cleaner 26, the intermediate transfer belt cleaner 56 is also in contact with the surface of the intermediate transfer belt 22 during cleaning, and is driven to rotate in the direction opposite to the rotation direction of the intermediate transfer belt 22 to scrape off residual transfer toner. Brush rolls 58A and 58B, two recovery rolls 60A and 60B for recovering toner from the respective brush rolls 58A and 58B, and two scrapers 62A and 62B for scraping off the toner from the respective recovery rolls 60A and 60B. Yes.

  On the lower left side of the image forming apparatus 10, a paper feed tray 64 for storing paper P is provided. Near the right side of the paper feed tray 64, a feed roll 66 that feeds the paper P from the paper feed tray 64 to the transport path 40 and a retard roll 68 that sprinkles the fed paper P one by one are arranged.

  A fixing device 70 having a heating roll 72 and a pressure roll 74 and a pair of discharge rolls 76 and 78 are provided on the right side of the lower right side in the apparatus. A discharge port 80 is formed in the right side wall portion of the apparatus corresponding to the discharge rolls 76 and 78, and a discharge tray 82 extending rightward (outside) is provided at the lower edge of the discharge port 80. It has been. The conveyance path 40 through which the paper P is conveyed extends from the feed roll 66 to the discharge rolls 76 and 78 via the secondary transfer portion T2, the conveyance belt 42, and the fixing device 70.

  Next, the polarity of the bias applied to each brush roll of each cleaner provided in the image forming apparatus 10 of the present embodiment will be described.

  Two brush rolls (cleaning brushes) provided on each of the photoreceptor cleaner 26, the conveyance belt cleaner 48, and the intermediate transfer belt cleaner 56 of the present embodiment are formed on the outer peripheral surface of a conductive roll shaft, for example, nylon fiber. A large number of conductive brushes made of, for example, are radially implanted.

  Here, as shown in FIG. 2, in the photoconductor cleaner 26, the brush roll 28 </ b> A disposed on the upstream side in the rotation direction of the photoconductor 12 (the toner image transport direction) has a positive polarity opposite to that of the toner image. A polarity bias is applied, and a negative polarity bias having the same polarity as the toner image is applied to the brush roll 28B disposed on the downstream side.

  Further, in the conveyor belt cleaner 48, a positive polarity bias is applied to the brush roll 50A disposed upstream in the rotational movement direction of the conveyor belt 42, and a negative polarity bias is applied to the brush roll 50B disposed downstream. Is done.

  Further, in the intermediate transfer belt cleaner 56, a negative polarity bias is applied to the brush roll 58A arranged on the upstream side in the rotational movement direction (toner image conveying direction) of the intermediate transfer belt 22, and the brush roll arranged on the downstream side. A positive polarity bias is applied to 58B.

  Next, a color image forming operation by the image forming apparatus 10 of the present embodiment configured as described above will be described.

  When an image forming signal is input to the image forming apparatus 10, the photosensitive member 12 is uniformly charged by the charging device 14, and the charged photosensitive member 12 is irradiated with laser light from the exposure device 16 based on the image forming signal. L is irradiated. With the laser light L, the surface of the photoconductor 12 is exposed to form an electrostatic latent image. The electrostatic latent image formed on the photoreceptor 12 is developed with yellow, magenta, cyan, and black toner images by the developing devices 20Y, 20M, 20C, and 20K of the rotary developing device 18, and is subjected to intermediate transfer at the primary transfer portion T1. Primary transfer is performed on the belt 22. Further, transfer residual toner remaining on the photoconductor 12 after the primary transfer is scraped and removed by the brush rolls 28A and 28B of the photoconductor cleaner 26.

  On the other hand, the paper P stored in the paper feed tray 64 is sent out by the feed roll 66, and is fed by the retard roll 18 so that only the uppermost paper P is guided to the transport path 40, and the secondary transfer roll at a predetermined timing. 44 and the secondary transfer backup roll 36, that is, sent to the secondary transfer portion T2. The toner image primarily transferred to the intermediate transfer belt 22 is secondarily transferred to the paper P at the secondary transfer portion T2. The sheet P on which the toner image is transferred is conveyed to the conveying belt 42 and guided to the fixing device 70, and the toner image is fixed by the thermal pressure of the heating roll 72 and the pressure roll 74. The paper P on which the image is formed by fixing the toner image is discharged from the discharge port 80 to the discharge tray 82 by the discharge rollers 76 and 78.

  Further, the transfer residual toner remaining in the image area of the intermediate transfer belt 22 after the secondary transfer is scraped and removed by the brush rolls 58A and 58B of the intermediate transfer belt cleaner 56, and the toner adhering to the conveyance belt 42 is removed. The brushes 50A and 50B of the cleaner 48 are scraped off and removed. Through the above operation, a color image is formed on the sheet by the image forming apparatus 10.

  Next, the operation of the image forming apparatus 10 of this embodiment will be described.

  In the image forming apparatus 10, when the toner TNA transferred (attached) from the intermediate transfer belt 22 to the conveyance belt 42 in the secondary transfer portion T2 enters the conveyance belt cleaner 48 as the conveyance belt 42 rotates, the rotating brush roll 58A rotates. , 58B is removed from the conveyor belt 42 by the mechanical scraping force. Here, when there is toner that is not removed by the conveyor belt cleaner 48 but is passed through, the toner TNB is charged with a negative polarity by applying a negative polarity bias from the brush roll 50B.

  Subsequently, when a positive-polarity bias having a polarity opposite to that at the time of transfer is applied to the secondary transfer portion T2 in the inter-image (non-image area) between the formed images (image areas), the toner TNB is removed from the transport belt 42. Reverse transfer is performed on the intermediate transfer belt 22.

  When the toner TNB transferred to the intermediate transfer belt 22 enters the intermediate transfer belt cleaner 56 as the intermediate transfer belt 22 rotates, it is recharged to a negative polarity by applying a negative polarity bias from the brush roll 58A. The adhesive force with the intermediate transfer belt 22 is weakened by the mechanical scraping force of the rotating brush roll 58A, and is favorably removed by the downstream brush roll 58B to which a positive polarity bias is applied.

  Further, when there is a toner that is not removed and is not removed by the intermediate transfer belt cleaner 56, the toner TNC is charged with a positive polarity by being applied with a positive polarity bias from the brush roll 58B.

  When the toner TNC returns to the primary transfer portion T1 as the intermediate transfer belt 22 rotates, and a positive transfer bias having the same polarity as that at the time of transfer is applied to the primary transfer portion T1, the toner TNC is removed from the intermediate transfer belt 22 above. It is reversely transferred to the photoreceptor 12.

  When the toner TNC transferred to the photoconductor 12 enters the photoconductor cleaner 26 as the photoconductor 12 rotates, a brush that rotates while being recharged to a negative polarity by applying a negative polarity bias from the brush roll 28A. The adhesive force with the photoconductor 12 is weakened by the mechanical scraping force of the roll 28A, and it is satisfactorily removed by the downstream brush roll 28B to which a positive polarity bias is applied.

  Even if the toner is slightly slipped by the photoconductor cleaner 26, the slipping toner TND is charged to a positive polarity by applying a positive polarity bias from the brush roll 28B. Development can be simultaneously collected by a rotary developing device 18 provided on the downstream side.

  As described above, in the image forming apparatus 10 of the present embodiment, even if the toner (toner TNA) adhering to the transport belt 42 slightly slips through the transport belt cleaner 48, the slip-through toner (toner TNB) is intermediated. It can be transferred to the transfer belt 22 and can be removed and collected well by the intermediate transfer belt cleaner 56. Even if the intermediate transfer belt cleaner 56 is slightly slipped, the slipping toner (toner TNC) can be transferred to the photoconductor 12 and can be satisfactorily removed and collected by the photoconductor cleaner 26. Further, even if the photosensitive member cleaner 26 is slightly slipped, the slipping toner (toner TND) can be simultaneously collected by the rotary developing device 18.

  Therefore, as described above, in the image forming apparatus 10 in which the cleaners of the photoconductor 12, the intermediate transfer belt 22, and the conveyor belt 42 (secondary transfer unit) are all brush-cleaned, toner that has slightly passed through the cleaner is retained. Therefore, defective cleaning and image defects due to accumulation can be prevented, and stable performance can be maintained with a long lifetime.

  As mentioned above, although this invention was demonstrated in detail by specific embodiment mentioned above, this invention is not limited to that embodiment, Various other forms can be implemented within the scope of the present invention.

1 is a configuration diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged configuration diagram illustrating a photoreceptor cleaner, a conveyance belt cleaner, and an intermediate transfer belt cleaner according to an embodiment of the present invention.

Explanation of symbols

10 Image forming apparatus 22 Intermediate transfer belt (intermediate transfer member)
26 Photoconductor cleaner (photoconductor cleaning means)
28A Brush roll (first photoreceptor brush roll)
28B Brush roll (second photoreceptor brush roll)
42 Conveyor belt (secondary transfer member)
44 Secondary transfer roll 48 Conveyor belt cleaner (secondary transfer member cleaning means)
50A brush roll (first secondary transfer member brush roll)
50B brush roll (first secondary transfer member brush roll)
56 Intermediate transfer belt cleaner (intermediate transfer member cleaning means)
58A Brush roll (first intermediate transfer body brush roll)
58B Brush roll (second intermediate transfer body brush roll)
P paper (recording medium)
TNA toner TNB toner TNC toner TND toner

Claims (2)

A toner image having a predetermined polarity formed on the rotating photosensitive member is primarily transferred to the surface, and the toner image is transported to the secondary transfer portion; and the second transfer member while rotating in the same direction as the transport direction. A secondary transfer member that secondary-transfers a toner image from the intermediate transfer member to a recording medium at a secondary transfer unit; an intermediate transfer member cleaning unit that removes residual toner remaining on the surface of the intermediate transfer member; and the secondary transfer member. An image forming apparatus comprising: a secondary transfer member cleaning unit that removes toner adhering to the surface of the member;
The intermediate transfer member cleaning means includes
A first intermediate transfer member brush roll that is applied with a bias having the same polarity as that of the toner image and rotationally contacts the surface of the intermediate transfer member;
A second intermediate transfer member, which is provided downstream of the first intermediate transfer member brush roll in the transport direction and is in rotational contact with the surface rotation of the intermediate transfer member by applying a bias having a polarity opposite to that of the toner image. Brush rolls,
Have
The secondary transfer member cleaning means includes
A first secondary transfer member brush roll that is applied with a bias having a polarity opposite to that of the toner image and rotationally contacts the surface of the secondary transfer member;
A second second member which is provided downstream of the first secondary transfer member brush roll in the rotational movement direction and is in rotational contact with the surface of the secondary transfer member by applying a bias having the same polarity as the toner image. A next transfer member brush roll;
An image forming apparatus comprising: A photosensitive member cleaning means for removing residual toner remaining on the surface of the photosensitive member;
The photoconductor cleaning means includes
A first photosensitive brush roll that is applied with a bias having a polarity opposite to that of the toner image and is in rotational contact with the surface of the photosensitive member;
A second photosensitive brush roll that is provided downstream of the first photosensitive brush roll in the rotational direction and is in rotational contact with the surface of the photosensitive member by applying a bias having the same polarity as the toner image;
The image forming apparatus according to claim 1, further comprising:

Images