JP2013242376A - Cleaning device, image carrier unit including the same, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent, in a cleaning device that is arranged above an image carrier and cleans the image carrier, occurrence of leakage of a toner accumulated on a seal member that contacts the image carrier to seal a gap between the cleaning device and the image carrier.SOLUTION: A polishing roller 353 rotatably contacts a rotating surface 31B of a photoreceptor drum 31 from the above. A seal roller 359 contacts the rotating surface 31B of the photoreceptor drum 31 on the upstream in a direction of rotation of the photoreceptor drum 31. The seal roller 359 prevents leakage of a toner recovered by the polishing roller 353. The seal roller 359 is rotated to be driven in the same direction as that of the cylindrical surface 31B of the photoreceptor drum 31 at a contact part with the cylindrical surface 31B. The seal roller 359 is applied with a bias having a polarity reverse to a polarity of a toner recovered from the photoreceptor drum 31.

Description

  The present invention relates to a cleaning device that cleans an image carrier that carries a toner image, an image carrier unit including the same, and an image forming apparatus.

  2. Description of the Related Art Conventionally, as an image forming apparatus that forms an image on a sheet, a technique is known in which a sheet passes from below to above through a transfer nip formed between a photosensitive drum and a transfer roller (patent) Reference 1). A toner image is formed on the photosensitive drum, and the toner image is transferred to a sheet at the transfer nip portion. The image forming apparatus further includes a fixing unit, and the sheet on which the toner image has been transferred is subjected to a fixing process in the fixing unit and then discharged.

  In the technique described in Patent Document 1, a cleaning device is disposed in the transfer nip portion so as to face the photosensitive drum in order to clean the residual toner on the photosensitive drum after the toner image is transferred. The As described above, when the sheet passes through the transfer nip portion from below to above, the cleaning device disposed downstream of the transfer nip portion in the rotation direction of the photosensitive drum is disposed above the photosensitive drum. Often.

  When the cleaning device is disposed above the photosensitive drum, residual toner removed from the photosensitive drum may fall from the periphery of the cleaning device. Therefore, a toner seal member is brought into contact with the photosensitive drum around the cleaning device in order to prevent the residual toner from falling. Patent Document 2 discloses a toner seal member having a roller shape that comes into contact with a rotating surface of a photosensitive drum.

JP 2009-8962 A Japanese Patent Laid-Open No. 9-237021

  When the cleaning device is disposed above the photosensitive drum as in the technique described in Patent Document 1, a large amount of toner accumulates above the toner seal member, and the toner causes the toner seal member to pass through the photosensitive drum. Press toward. For this reason, the contact pressure of the toner seal member with respect to the photosensitive drum increases. Then, the paper dust on the sheet adheres to the cylindrical surface of the image carrier at the transfer nip portion, and the paper dust moved to the tip of the toner seal member as the photosensitive drum rotates is moved to the tip of the toner seal member. Grown into a lump between the cylindrical surface of the image carrier. As a result, the tip of the toner seal member may be lifted by the lump of paper powder, causing problems such as toner leakage.

  Further, as in the technique described in Patent Document 2, when the roller member that is rotationally driven is brought into contact with the photosensitive drum as a toner seal member, the toner collected by the cleaning device is scattered around. Sometimes.

  The present invention has been made in view of the above-described problems. In a cleaning device that is disposed above an image carrier and cleans the image carrier, and an image carrier unit including the cleaning device, or an image forming apparatus, a cleaning device is provided. An object of the present invention is to prevent toner leakage caused by toner deposited on a seal member that seals between the apparatus and the image carrier.

  A cleaning device according to one aspect of the present invention is disposed above an image carrier including a rotation shaft and a cylindrical surface that rotates in one direction around the rotation shaft and supports a toner image, and the cylindrical surface A housing and a rotating surface that contacts the cylindrical surface above the rotating shaft in a cross-sectional view orthogonal to the rotating shaft, and the image carrier at the contact position A rotating member that is driven to rotate in the same direction as the toner and collects toner adhering to the image carrier, and is disposed in the casing, and is above the rotating shaft in the cross-sectional view, and the rotating member A seal roller that is in contact with the cylindrical surface on the upstream side in the rotational direction of the image carrier, and a bias is applied to the seal roller that is driven to rotate in the same direction as the cylindrical surface at the contact portion. Via applied And applying means, characterized in that it comprises a.

  According to this configuration, the cleaning device includes the rotating member and the seal roller. The rotating member contacts the cylindrical surface above the rotation axis of the image carrier. The rotating member is driven to rotate and collects toner adhering to the image carrier. Even when the collected toner collected from the image carrier is scattered from the rotating surface of the rotating member, the seal roller contacts the cylindrical surface on the upstream side of the rotating member in the rotating direction of the image bearing member. . The seal roller is driven to rotate in the same direction as the cylindrical surface of the image carrier. For this reason, the toner and paper dust adhering to the cylindrical surface of the image carrier are smoothly guided to the inside of the cleaning device via the seal roller. Further, rotation of the seal roller prevents the collected toner from being deposited on the seal roller. As a result, the toner deposited on the seal roller is prevented from pressing the seal roller toward the image carrier. Accordingly, the contact pressure of the seal roller with respect to the image carrier is unlikely to be high, and toner leakage from the peripheral surface of the seal roller is suppressed. Further, a bias is applied to the seal roller. For this reason, it is possible to electrically attract the toner collected from the image carrier to the cleaning device to the seal roller side. As a result, the leakage of toner from the periphery of the seal roller to the upstream side in the rotational direction of the cylindrical surface of the image carrier is suppressed.

  In the above configuration, the image forming apparatus further includes bias control means for controlling the bias applied to the seal roller, and the bias control means applies a bias having a polarity opposite to a normal charging polarity of the toner to the seal roller. It is desirable to apply to.

  According to this configuration, the bias control unit applies a bias having a polarity opposite to the normal charging polarity of the toner to the seal roller. For this reason, it is possible to attract the toner charged to the normal polarity and adhered to the cylindrical surface of the image carrier to the seal roller side.

  Said structure WHEREIN: The scraping member contact | abutted to the surrounding surface of the said sealing roller is provided in the rotation direction downstream of the said sealing roller rather than the said contact part along the direction where the said rotating shaft is extended. Is desirable.

  According to this configuration, excessive toner is prevented from being accumulated on the peripheral surface of the seal roller. Therefore, it is possible to suppress the toner from dropping from the peripheral surface of the seal roller to the cylindrical surface of the image carrier on the upstream side in the rotation direction from the seal roller.

Said structure WHEREIN: The said housing has a standing wall arrange | positioned facing the said rotation member,
The seal roller is preferably disposed at a lower end portion of the standing wall.

  According to this configuration, the toner scattered from the rotating surface of the rotating member falls on the seal roller after colliding with the standing wall. Since the seal roller is rotationally driven, a toner flow is formed around the seal roller. For this reason, the dropped toner is easily moved to the image carrier side.

  In the above-described configuration, it is preferable that the image forming apparatus further includes a cleaning blade that contacts the cylindrical surface on the downstream side in the rotation direction of the image carrier with respect to the rotating member and removes toner adhering to the image carrier.

  According to this configuration, the cleaning blade is disposed on the downstream side in the rotation direction of the image carrier with respect to the rotation member. For this reason, the toner adhering to the image carrier is accurately removed.

  In the above configuration, the rotating member is a polishing roller that polishes deposits attached to the cylindrical surface of the image carrier, and is a toner that contacts the rotating surface of the polishing roller and adheres to the rotating surface. It is preferable to further include a regulating member that regulates the amount.

  According to this configuration, the deposit adhered to the cylindrical surface of the image carrier is effectively polished by the polishing roller. Further, the regulating member regulates the amount of toner that adheres to the rotating surface of the polishing roller. For this reason, when the toner is uniformly interposed between the polishing roller and the cylindrical surface of the image carrier, the promoted polishing effect is suppressed from being varied depending on the position on the rotating surface of the polishing roller.

  An image carrier unit according to another aspect of the present invention includes the cleaning device according to any one of the above, and the image carrier disposed to face the seal roller.

  According to this configuration, even when the collected toner collected from the image carrier is scattered from the circumferential surface of the rotating member, the cylindrical surface on the upstream side in the rotation direction of the image carrier from the rotating member is disposed on the cylindrical surface. The seal roller comes into contact. The seal roller is driven to rotate in the same direction as the cylindrical surface of the image carrier. For this reason, the toner and paper dust adhering to the cylindrical surface of the image carrier are smoothly guided to the inside of the cleaning device via the seal roller. Further, rotation of the seal roller prevents the collected toner from being deposited on the seal roller. As a result, the toner deposited on the seal roller is prevented from pressing the seal roller toward the image carrier. Accordingly, the contact pressure of the seal roller with respect to the image carrier is unlikely to be high, and toner leakage from the peripheral surface of the seal roller is suppressed.

  An image forming apparatus according to another aspect of the present invention includes the above-described cleaning device, the image carrier disposed to face the seal roller, and development for supplying toner to the cylindrical surface of the image carrier. A transfer member that is rotationally driven opposite to the image carrier and transfers the toner image from the image carrier to a sheet; and a transfer bias applying unit that applies a transfer bias to the transfer member; Transfer bias control means for controlling the transfer bias applied to the transfer member, wherein the transfer bias control means applies a bias to the transfer member having a polarity opposite to the normal charging polarity of the toner. A reverse charging toner recovery mode to be applied, wherein the bias control means has the same regular charging polarity as the reverse charging toner recovery mode of the transfer bias control means. Sexual bias, and applying to the sealing roller.

  According to this configuration, the transfer bias control unit includes a reversely charged toner recovery mode in which a bias having a polarity opposite to the normal charging polarity of the toner is applied to the transfer member. Even when the reversely charged toner on the transfer member is recovered on the image carrier in the reversely charged toner recovery mode, the bias control unit performs the above operation according to the reversely charged toner recovery mode of the transfer bias control unit. A bias having the same polarity as the normal charging polarity is applied to the seal roller. Therefore, the reversely charged toner collected by the cleaning device can be attracted from the image carrier side to the seal roller side. As a result, it is possible to prevent the reversely charged toner from leaking from the periphery of the seal roller to the upstream side in the rotation direction of the cylindrical surface of the image carrier.

  An image forming apparatus according to another aspect of the present invention, the cleaning device according to any one of the above, the image carrier disposed to face the seal roller, and the cylindrical surface of the image carrier, And a developing device for supplying toner.

  According to this configuration, the seal roller contacts the cylindrical surface on the upstream side in the rotation direction of the image carrier with respect to the rotation member. The seal roller is driven to rotate in the same direction as the cylindrical surface of the image carrier. For this reason, the toner and paper dust adhering to the cylindrical surface of the image carrier are smoothly guided to the inside of the cleaning device via the seal roller. Further, rotation of the seal roller prevents the collected toner from being deposited on the seal roller. As a result, the toner deposited on the seal roller is prevented from pressing the seal roller toward the image carrier. Accordingly, the contact pressure of the seal roller with respect to the image carrier is unlikely to be high, and toner leakage from the peripheral surface of the seal roller is suppressed.

  In the above-described configuration, a sheet conveying path that conveys a sheet from below to above facing the image carrier, and abutting against the cylindrical surface of the image carrier, the toner image from the image carrier And a transfer member that forms a transfer nip portion for transferring the image to the sheet, and the image carrier is rotationally driven from below to above in the transfer nip portion. To the cylindrical surface of the image carrier between the position and the position directly above the rotation shaft.

  According to this configuration, the rotating member comes into contact with the cylindrical surface of the image carrier from the transfer nip portion to a position immediately above the rotation axis of the image carrier. The seal roller is in contact with the cylindrical surface on the upstream side in the rotation direction of the image carrier, below the position where the rotating member contacts the cylindrical surface. For this reason, the toner scattered from the rotating member tends to fall on the seal roller. Even in such a case, since the sealing roller is driven to rotate, the collected toner is prevented from being deposited on the sealing roller. As a result, the toner deposited on the seal roller is prevented from pressing the seal roller toward the image carrier. The seal roller is rotationally driven in the same direction as the rotation direction of the cylindrical surface of the image carrier, and a bias is applied. Therefore, the toner adhering to the cylindrical surface of the image carrier is smoothly guided into the cleaning device and attracted to the seal roller side. Therefore, the collected toner is prevented from leaking from between the seal roller and the image carrier. As a result, the conveyed sheet is prevented from being soiled by the leaked toner in the transfer nip portion.

  According to the present invention, in a cleaning device that is disposed above an image carrier and cleans the image carrier, and an image carrier unit or an image forming apparatus including the same, a gap between the cleaning device and the image carrier is sealed. The toner accumulated on the sealing member to be stopped is prevented from causing toner leakage.

1 is a perspective view illustrating an appearance of an image forming apparatus 1 according to an embodiment of the present disclosure. 1 is a cross-sectional view illustrating an internal structure of an image forming apparatus 1 according to an embodiment of the present invention. It is a sectional side view which shows the internal structure of the image carrier unit which concerns on one Embodiment of this invention. It is a sectional side view which shows the internal structure of the image carrier unit compared with this invention. FIG. 4 is a schematic diagram for explaining a state where toner is accumulated on a toner seal. FIG. 6 is a schematic diagram for explaining a state in which a front end portion of the toner seal is lifted by a lump of paper powder. It is an expanded sectional view of image carrier unit 31H concerning one embodiment of the present invention. It is a figure which shows the polarity of the bias applied to a seal roller. It is a figure which shows the polarity of the bias applied to the seal roller at the time of a belt cleaning operation | movement.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 schematically shows an internal structure of image forming apparatus 1 shown in FIG. FIG. 3 is an enlarged cross-sectional view of the periphery of the drum unit 31 </ b> H inside the image forming apparatus 1. In FIG. 2, the upper housing 22 of FIG. 1 does not appear. The image forming apparatus 1 shown in FIGS. 1 and 2 is a so-called monochrome printer, but in other embodiments, the image forming apparatus is a color printer, a facsimile machine, a multifunction machine having these functions, or a toner image. Other devices for forming the sheet may be used. Note that the terms used in the following description, such as “up”, “down”, “front”, “rear”, “left” and “right”, are merely for the purpose of clarifying the description. There is no limitation on the principle of the image forming apparatus. Further, in the following description, the term “sheet” means copy paper, coated paper, OHP sheet, cardboard, postcard, tracing paper, other sheet material subjected to image forming processing, or any processing other than image forming processing. Means the sheet material to receive.

  The image forming apparatus 1 includes a main housing 2 having a substantially rectangular parallelepiped shape. The main housing 2 connects a substantially rectangular parallelepiped lower housing 21, a substantially rectangular parallelepiped upper housing 22 disposed above the lower housing 21, and the lower housing 21 and the upper housing 22. And a connecting housing 23. The connection housing 23 extends along the right edge and the back edge of the main housing 2. The sheet subjected to the printing process is discharged into a discharge space 24 surrounded by the lower casing 21, the upper casing 22, and the connecting casing 23.

  The operation unit 221 protruding in the front direction of the upper housing 22 includes, for example, an LCD touch panel 222. The operation unit 221 is formed so as to be able to input information related to the image forming process. For example, the user can input the number of sheets to be printed, the print density, and the like through the LCD touch panel 222. Housed in the upper housing 22 are mainly an apparatus for reading an image of a document and an electronic circuit that controls the entire image forming apparatus 1.

  A pressing cover 223 disposed on the upper housing 22 is used for pressing the document. The presser cover 223 is attached to the upper housing 22 so as to be rotatable up and down. The user rotates the holding cover 223 upward to place the document on the upper housing 22. Thereafter, the user can operate the operation unit 221 to read an image of the document on a device provided in the upper housing 22.

  A manual feed tray 240 is disposed on the right side surface of the lower housing 21. The manual feed tray 240 can be rotated up and down on the upper end 240B side with the lower end 240A (FIG. 2) as a fulcrum. The user can place a sheet on the manual feed tray 240 when the manual feed tray 240 is rotated downward and the manual feed tray 240 is in a position protruding to the right of the lower housing 21. The sheet on the manual feed tray 240 is drawn into the lower housing 21 based on an instruction input by the user through the operation unit 221, is subjected to image forming processing, and is discharged into the discharge space 24.

  With reference to FIG. 2, the image forming apparatus 1 includes a cassette 110, a paper feeding unit 11, a second paper feeding roller 114, an intermediate roller 115, a registration roller pair 116, and an image forming unit 120. The paper feed unit 11 includes a pickup roller 112 and a first paper feed roller 113. The sheet feeding unit 11 sends the sheet P to the sheet conveyance path PP. The sheet conveyance path PP is disposed so as to pass from the sheet feeding unit 11 through the intermediate roller pair 115 and the registration roller pair 116 to the transfer position TP (FIG. 3) disposed in the image forming unit 120. It is a transport path.

  The cassette 110 accommodates the sheet P inside. The cassette 110 can be pulled out from the lower housing 21 in the front direction (the front side in FIG. 2). The sheet P accommodated in the cassette 110 is sent upward in the lower housing 21. Thereafter, the sheet P is subjected to an image forming process in the lower housing 21 based on an instruction input by the user through the operation unit 221, and is discharged to the discharge space 24. The cassette 110 includes a lift plate 111 that supports the sheet P. The lift plate 111 is inclined so as to push up the leading edge of the sheet P upward.

  The pickup roller 112 is disposed on the leading edge of the sheet P pushed upward by the lift plate 111. When the pickup roller 112 rotates, the sheet P is pulled out from the cassette 110.

  The first paper feed roller 113 is disposed downstream of the pickup roller 112 in the sheet conveyance direction. The first paper feed roller 113 sends the sheet P further downstream. The second paper feed roller 114 is disposed inside the manual feed tray 240. The second paper feed roller 114 pulls the sheet P on the manual feed tray 240 into the lower housing 21. The user can selectively use the sheet P stored in the cassette 110 or the sheet P placed on the manual feed tray 240.

  The intermediate roller pair 115 is disposed downstream of the first paper feed roller 113 and the second paper feed roller 114 in the sheet conveyance direction. The intermediate roller pair 115 conveys the sheet P sent out by the first paper feed roller 113 and the second paper feed roller 114 further downstream.

  The registration roller pair 116 defines the position of the sheet in a direction orthogonal to the sheet conveyance direction. Thereby, the position of the image formed on the sheet P is adjusted. The registration roller pair 116 forms a nip portion between the rollers. The registration roller pair 116 conveys the sheet P to the image forming unit 120 in accordance with the timing at which the toner image is transferred to the sheet P in the image forming unit 120. The registration roller pair 116 has a function of correcting skew (skew) of the sheet P.

  Referring to FIG. 2, the image forming unit 120 includes a photosensitive drum 31, a charging device 32, an exposure device 123, a developing device 124, a toner container 125, a transfer roller 126, a conveyance belt 180, and a cleaning. Device 35. The photosensitive drum 31, the charging device 32, and the cleaning device 35 are integrally disposed as a drum unit 31H described later.

  The photosensitive drum 31 has a substantially cylindrical shape. The photosensitive drum 31 forms an electrostatic latent image on the peripheral surface (cylindrical surface) and carries a toner image corresponding to the electrostatic latent image. The photosensitive drum 31 includes a rotation shaft 31A and a cylindrical surface 31B (FIG. 3).

  The charging device 32 is applied with a predetermined voltage and charges the peripheral surface of the photosensitive drum 31 substantially uniformly. The exposure device 123 irradiates the peripheral surface of the photosensitive drum 31 charged by the charging device 32 with laser light. The laser light is emitted in accordance with image data output from an external device (not shown) such as a personal computer that is communicably connected to the image forming apparatus 1. As a result, an electrostatic latent image corresponding to the image data is formed on the peripheral surface of the photosensitive drum 31.

  The developing device 124 supplies toner to the peripheral surface of the photosensitive drum 31 on which the electrostatic latent image is formed. The toner container 125 supplies toner to the developing device 124. The toner container 125 supplies toner to the developing device 124 sequentially or as necessary. When the developing device 124 supplies toner to the photosensitive drum 31, the electrostatic latent image formed on the peripheral surface of the photosensitive drum 31 is developed (visualized). As a result, a toner image is formed on the peripheral surface of the photosensitive drum 31. The developing device includes a developing roller that carries toner on a peripheral surface. The developing roller is driven to rotate and supplies toner to the photosensitive drum 31.

  The transfer roller 126 is disposed to face the peripheral surface of the photosensitive drum 31 at the transfer position TP (FIG. 3). The transfer roller 126 is disposed so as to contact the inner peripheral surface of the conveyance belt 180 and to face the photosensitive drum 31.

  The conveyor belt 180 is an endless belt. The conveyance belt 180 is driven to rotate, carries the sheet P on its surface, and conveys the sheet P to the transfer position TP. The conveyor belt 180 transmits a rotational driving force to the transfer roller 126 via the inner peripheral surface. The conveyance belt 180 is stretched by a stretching roller 182 and a driving roller 181 on the upstream side and the downstream side in the sheet conveyance direction from the transfer roller 126. The driving roller 181 receives a rotational driving force from a driving unit (not shown) and rotates the conveyor belt 180. The transfer roller 126 and the stretching roller 182 rotate along with the conveyance belt 180 and rotate at the same speed as the conveyance belt 180. When the sheet P passes the transfer position TP, the toner image formed on the peripheral surface of the photosensitive drum 31 is transferred to the sheet P. At this time, a transfer bias described later is applied to the transfer roller 126.

  The cleaning device 35 removes the toner remaining on the peripheral surface of the photosensitive drum 31 after the toner image is transferred to the sheet P. The peripheral surface of the photosensitive drum 31 cleaned by the cleaning device 35 passes below the charging device 32 again and is uniformly charged. Thereafter, the above-described toner image is newly formed. The structure of the cleaning device 35 will be described in detail later.

  The image forming apparatus 1 further includes a fixing device 130 (FIG. 2) that fixes the toner image on the sheet P on the downstream side in the transport direction from the image forming unit 120. The fixing device 130 includes a heating roller 131 that melts the toner on the sheet P, and a pressure roller 132 that causes the sheet P to adhere to the heating roller 131. When the sheet P passes between the heating roller 131 and the pressure roller 132, the toner image is fixed on the sheet P.

  The image forming apparatus 1 further includes a transport roller pair 133 disposed downstream of the fixing device 130 and a discharge roller pair 134 disposed downstream of the transport roller pair 133. The sheet P is discharged from the lower housing 21 by the conveyance roller pair 133 and the discharge roller pair 134. The sheets P discharged from the lower housing 21 are stacked on the upper wall 210.

  Further, the configuration of the drum unit 31H according to the present embodiment will be described in detail with reference to FIGS. FIG. 4 is an enlarged sectional view of the drum unit 31HW for comparison and reference with respect to the drum unit 31H.

  With reference to FIG. 3, the drum unit 31 </ b> H includes the above-described photosensitive drum 31, a charging device 32, and a cleaning device 35. The drum unit 31H includes a pair of side plates (not shown) at both ends in the left-right direction (a direction orthogonal to the paper surface of FIG. 3). The photosensitive drum 31 is rotatably supported by the pair of side plates. Further, the charging device 32 and the cleaning device 35 are supported by the pair of side plates so as to face the photosensitive drum 31. In FIG. 3, the photosensitive drum 31 is rotationally driven in the direction of arrow DP by a driving unit (not shown). The drum unit 31H includes a fixing part (not shown) disposed on the side plate. When the drum unit 31H is mounted on the lower casing 21 of the image forming apparatus 1, the fixing portion is fixed to the lower casing 21 of the image forming apparatus 1. As a result, in the image forming apparatus 1, the position of the drum unit 31H is fixed. The fixing part is configured by a fastening hole to which a screw is fastened.

  The charging device 32 is disposed in front of the photosensitive drum 31. The charging device 32 includes a charging roller 321, a cleaning roller 322, and a charging housing 32H. The charging housing 32 </ b> H has a substantially U-shaped shape in a cross-sectional view orthogonal to the rotation axis of the photosensitive drum 31. A charging roller 321 and a cleaning roller 322 are rotatably supported in the charging housing 32H.

  The charging roller 321 is a roll member whose surface is made of a rubber material. A charging voltage is applied to the charging roller 321 from a charging bias applying unit (not shown). The charging roller 321 is rotated while being driven by the photosensitive drum 31 by contacting the circumferential surface of the photosensitive drum 31. The peripheral surface of the photosensitive drum 31 is uniformly charged by the charging roller 321 to which the charging voltage is applied.

  The charging cleaning roller 322 contacts the charging roller 321 and rotates with the charging roller 321 with a linear velocity difference. The charging cleaning roller 322 is a brush roller formed of conductive nylon fibers. When the charging roller 321 comes into contact with the surface of the photosensitive drum 31, toner, foreign matter, or the like adheres to the surface of the charging roller 321. By rotating the charging cleaning roller 322 with a difference in linear velocity while contacting the charging roller 321, toner, foreign matters, and the like attached to the surface of the charging roller 321 are preferably removed.

  The cleaning device 35 is disposed above the photosensitive drum 31. The cleaning device 35 includes a cleaner housing 35H (housing), a cleaning blade 351, a conveying screw 352, and a polishing roller 353 (rotating member). The cleaning device 35 includes a scraper 354, a scraper holder 355, and an upper seal 356. Further, the cleaning device 35 includes a seal roller 359.

  The cleaner housing 35 </ b> H is a housing that supports each member in the cleaning device 35. The cleaning device 35 is disposed so as to cover the photosensitive drum 31 and the charging device 32 upward. In particular, the front portion of the cleaner housing 35H is disposed above the charging roller 321. Further, in the cross-sectional view orthogonal to the rotation axis of the photosensitive drum 31, the central portion in the front-rear direction of the cleaner housing 35H has a shape protruding upward in an arc shape. Further, the rear portion of the cleaner housing 35H is defined by the housing rear wall 35H1 (standing wall). The housing rear wall 35H1 is a wall portion extending in the vertical direction. The housing rear wall 35H1 is disposed to face a polishing roller 353 described later. A seal roller 359 is disposed at the lower end of the housing rear wall 35H1.

  The cleaning blade 351 is disposed in the horizontal direction along the bottom of the cleaner housing 35H. The cleaning blade 351 is a plate-like member made of a rubber material. The cleaning blade 351 is supported by the blade holder 351H. The blade holder 351H is a sheet metal member having an L-shape in the cross-sectional view. A central portion of the blade holder 351H is fixed to the cleaner housing 35H by the first fixing screw 351B. The cleaning blade 351 and the blade holder 351H are fixed with an adhesive. As a result, a fixed end of the cleaning blade 351 is formed. On the other hand, the front end of the cleaning blade 351 is a free end and is in contact with the cylindrical surface 31 </ b> B of the photosensitive drum 31. The tip of the cleaning blade 351 is in contact with the cylindrical surface 31B on the downstream side in the rotation direction (arrow DP direction) of the photosensitive drum 31 with respect to a later-described polishing roller 353. As a result, the toner remaining (attached) on the cylindrical surface 31B of the photosensitive drum 31 is removed by the tip of the cleaning blade 351.

  The conveying screw 352 is rotatably supported by the cleaner housing 35H above the cleaning blade 351. The conveying screw 352 includes a shaft portion and a spiral blade member disposed around the shaft portion. The conveying screw 352 is scraped off by the cleaning blade 351 and conveys the collected toner PT accumulated on the cleaning blade 351 in the axial direction of the rotating shaft 31 </ b> A of the photosensitive drum 31.

  The polishing roller 353 is disposed behind the conveying screw 352. The polishing roller 353 includes a rotating surface that comes into contact with the cylindrical surface 31B above the rotating shaft 31A of the photosensitive drum 31. Further, the polishing roller 353 contacts the cylindrical surface 31B of the photosensitive drum 31 from the transfer nip portion TP to a position directly above the rotation shaft 31A of the photosensitive drum 31. More specifically, the polishing roller 353 contacts the cylindrical surface 31B directly above the rotation shaft 31A of the photosensitive drum 31 or slightly upstream of the photosensitive drum 31 in the rotation direction. The position where the polishing roller 353 contacts on the cylindrical surface 31B is defined as a contact position CP. The polishing roller 353 is a rubber roller having a roughened peripheral surface. In this embodiment, a shaft having a diameter of 12 mm and an EPDM rubber (ethylene propylene rubber) having a thickness of 1.75 mm are used. Is done. The polishing roller 353 is rotated following the photosensitive drum 31 while being in contact with the cylindrical surface 31B of the photosensitive drum 31 (arrow DC). The polishing roller 353 collects the toner attached to the cylindrical surface 31B of the photosensitive drum 31. Further, the polishing roller 353 polishes deposits such as a discharge product attached to the surface of the photosensitive drum 31. At this time, a predetermined amount of toner adheres to the rotating surface of the polishing roller 353, thereby improving the discharge product removal performance (polishing performance).

  The scraper 354 (regulating member) is a plate-like member extending in the vertical direction (vertical direction). In the present embodiment, the scraper 354 is composed of a 0.05 mm SUS plate. The lower end of the scraper 354 is in contact with the rotating surface of the polishing roller 353. The lower end of the scraper 354 is in contact with the rotation surface of the polishing roller 353 so as to face the rotation direction (arrow DC direction) of the polishing roller 353. When the scraper 354 comes into contact with the rotating surface of the polishing roller 353 with a predetermined elastic force, the amount of toner attached to the rotating surface of the polishing roller 353 is regulated. As a result, since the amount of toner adhering to the rotating surface of the polishing roller 353 becomes uniform, variation in the discharge product removal performance by the polishing roller 353 is suppressed.

  The scraper holder 355 is disposed so as to cover the upper part of the polishing roller 353. The scraper holder 355 is composed of a bent sheet metal member. The central portion of the scraper holder 355 extends in the horizontal direction. A front portion of the scraper holder 355 is bent downward to support the scraper 354. Further, the rear portion of the scraper holder 355 is bent rearward and downward.

  The upper seal 356 is fixed on the scraper holder 355. One end of the upper seal 356 is supported at the center of the scraper holder 355, and the other end of the upper seal 356 is disposed so as to protrude forward from the scraper holder 355. The upper seal 356 has a function of blocking the toner that has jumped upward when the toner attached to the rotating surface of the polishing roller 353 is scraped off by the scraper 354.

The seal roller 359 is disposed at the lower end of the housing rear wall 35H1. The seal roller 359 includes a metal shaft (not shown) and a cylindrical conductive urethane rubber arranged around the shaft. The shaft is inserted into a bearing portion disposed on the side wall in the left-right direction of the cleaner housing 35H, and the seal roller 359 is rotatably supported. A part of the peripheral surface of the seal roller 359 comes into contact with the cylindrical surface 31 </ b> B of the photosensitive drum 31. In the present embodiment, the seal roller 359 is rotationally driven by a driving unit (not shown) at the same speed as the cylindrical surface 31B of the photosensitive drum 31 or at a slightly higher speed than the photosensitive drum 31B. The seal roller 359 is rotated in the same direction as the cylindrical surface 31B at the contact portion with the cylindrical surface 31B of the photosensitive drum 31. The seal roller 359 prevents toner from leaking out of the cleaning device 35. Further, the seal roller 359 receives the toner and paper dust attached to the cylindrical surface 31 </ b> B of the photosensitive drum 35 into the cleaning device 35. The seal roller 359 may be composed of an elastic member other than urethane rubber. In other embodiments, the seal roller 359 may be composed of a cylindrical urethane sponge. At this time, the slidability between the seal roller 359 and the cylindrical surface 31B of the photosensitive drum 31 is improved by disposing a tube member made of PET film or the like on the surface of the urethane sponge.

  The photosensitive drum 31 whose peripheral surface is uniformly charged by the charging roller 321 of the charging device 32 forms an electrostatic latent image by an exposure device (not shown) on the downstream side of the charging device 32 in the rotation direction. Then, the electrostatic latent image is visualized as a toner image by the developing device 124 (FIG. 2) disposed below the photosensitive drum 31. The photosensitive drum 31 is rotated from below to above in the transfer nip portion TP. The toner image formed on the photoconductive drum 31 is transferred to a sheet conveyed from the lower side to the upper side of the transfer nip portion TP.

  In the transfer nip portion TP, a part of the toner image transferred to the sheet remains on the photosensitive drum 31 as residual toner. Residual toner on the photoconductive drum 31 is conveyed from the lower side to the upper side with the rotation of the photoconductive drum 31 to a region where the cleaning device 35 faces the photoconductive drum 31.

  Part of the residual toner transported to the area facing the cleaning device 35 adheres to the rotating surface of the polishing roller 353. Residual toner that has not adhered to the rotating surface of the polishing roller 353 is scraped off by the cleaning blade 351.

  Next, the problem of the toner seal member disposed in the cleaning device 35 will be described. Part of the toner adhering to the rotating surface of the polishing roller 353 is scraped off by the scraper 354. The toner that passes through the tip of the scraper 354 and remains on the rotating surface of the polishing roller 353 is circulated on the polishing roller 353 while passing through a region facing the scraper holder 355 and the housing rear wall 35H1. At this time, the toner attached to the rotating surface of the polishing roller 353 is separated from the polishing roller 353 by the centrifugal force of the polishing roller 353. The toner released from the polishing roller 353 is scattered in a region surrounded by the scraper holder 355, the housing rear wall 35H1, and the cylindrical surface 31B of the photosensitive drum 31.

  FIG. 4 is a view for comparison with the cleaning device 35 according to the embodiment of the present invention, and is a cross-sectional view of a drum unit 31HW provided with the cleaning device 35W. The cleaning device 35W differs from the cleaning device 35 according to the present embodiment in the structure around the housing rear wall 35H1. For this reason, the difference will be mainly described, and description of other parts will be omitted. The cleaning device 35W includes a cleaner housing 35HW, a housing rear wall 35H1W, a polishing roller 353W, a plate 358W, and a toner seal 380.

  The housing rear wall 35H1W of the cleaner housing 35HW is disposed on the rear side of the housing rear wall 35H1. The plate 358W is fixed to the rear side surface of the housing rear wall 35H1W. A plate lower portion 358WS, which is a lower end portion of the plate 358W, is bent forward and is disposed below the housing rear wall 35H1W.

  The toner seal 380 is made of a urethane sheet. The toner seal 380 is fixed to the plate lower portion 358WS in the horizontal direction. One end of the toner seal 380 is bonded to the lower plate portion 358WS to form a fixed end of the toner seal 380. On the other hand, the other end of the toner seal 380 forms a free end of the toner seal 380 and abuts on the cylindrical surface 31WB of the photosensitive drum 31W. A space exists above the portion of the toner seal 380 that extends forward from the lower plate portion 358WS.

  Since the space exists above the toner seal 380, the toner scattered from the rotating surface of the polishing roller 353W accumulates on the toner seal 380 and forms a toner reservoir TN. FIG. 5 and FIG. 6 are views showing a state around the toner seal 380 at this time. Referring to FIG. 5, the toner reservoir TN accumulated on the toner seal 380 is piled up so as to form a mountain shape. Generally, the angle of repose of toner collected by the cleaning device 35 is 30 degrees to 40 degrees. However, the collected toner is likely to adhere to a member made of a resin material or a rubber material located around it with static electricity. For this reason, in the region where the polishing roller 353W and the housing rear wall 35H1W are close to each other, the repose angle of the collected toner may be 60 degrees to 70 degrees. Therefore, the toner reservoir TN is unlikely to collapse and a large amount of toner accumulates on the toner seal 380.

  On the other hand, when the toner image is transferred to the sheet P in the transfer nip portion TP, the paper dust attached to the surface of the sheet P may be moved to the cylindrical surface 31WB of the photosensitive drum 31W. The paper dust adhering to the cylindrical surface 31WB of the photosensitive drum 31W is conveyed toward the tip of the toner seal 380 as the photosensitive drum 31W rotates. When the toner reservoir TN is not formed on the toner seal 380, the tip of the toner seal 380 is in contact with the cylindrical surface 31WB of the photosensitive drum 31W with a low contact pressure. In this case, the paper dust conveyed on the photosensitive drum 31W passes between the tip of the toner seal 380 and the cylindrical surface 31WB of the photosensitive drum 31W and is collected by the cleaning blade 351W.

  However, when the tip of the toner seal 380 is strongly in contact with the cylindrical surface 31WB of the photosensitive drum 31W due to the toner reservoir TN accumulated on the toner seal 380, the paper dust is exposed to the tip of the toner seal 380 and the photosensitive drum 31W. It cannot pass between the cylindrical surface 31WB of the body drum 31W. As a result, as shown in FIG. 5, a lump PD of paper dust is formed between the tip of the toner seal 380 and the cylindrical surface 31WB of the photosensitive drum 31.

  When the paper powder lump PD is grown, the toner seal 380 is lifted from the cylindrical surface 31WB of the photoconductive drum 31W in the axial direction of the rotation shaft 31WA of the photoconductive drum 31W corresponding to the portion where the lump PD is present. (FIG. 6). As a result, the toner TN1 starts to leak from the toner reservoir TN. The toner TN1 falls along the cylindrical surface 31WB of the photosensitive drum 31W according to gravity (arrow DT). Then, the toner TN1 reaching the transfer nip portion TP adheres to the sheet P conveyed to the transfer nip portion TP. As a result, toner contamination occurs on the sheet P.

  Further, when the free end of the toner seal 380 comes into contact with the cylindrical surface 31WB of the photosensitive drum 31W, the free end is likely to have a partial wave in the axial direction. For this reason, toner leakage tends to occur corresponding to the portion where the wave is generated.

  As described above, the toner scattered from the polishing roller 353W is deposited above the toner seal 380 of the cleaning device 35W. A paper powder lump PD is generated between the toner seal 380 and the photosensitive drum 31W. As a result, the toner stain on the sheet P is brought about. The cleaning device 35 according to the present embodiment is characterized by the shape and control of the seal roller 359 in order to solve the above problems.

  FIG. 7 is an enlarged cross-sectional view of the periphery of the cleaning device 35 and the conveyance belt 180 of FIG. The cleaning device 35 further includes a scraping member 360, a bias control unit 501, and a bias application unit 502.

  The scraping member 360 is a plate-like member that comes into contact with the surface of the seal roller 359. The scraping member 360 is along the direction in which the rotation shaft 31A of the photosensitive drum 31 extends from the contact portion between the cylindrical surface 31B of the photosensitive drum 31 and the sealing roller 359 on the downstream side in the rotation direction of the sealing roller. In contact with the peripheral surface of the seal roller. At this time, the scraping member 360 is brought into contact with the seal roller 359 so as to face the rotation direction of the seal roller 359. The scraping member 360 scrapes off the toner and paper dust adhering to the surface of the seal roller 359 and drops it onto the cylindrical surface 31B of the photosensitive drum 31.

  The bias control unit 501 controls the bias application unit 502 to apply a bias to the seal roller 359. The bias application unit 502 is a power source for applying the bias to the seal roller 359. In the present embodiment, the bias application unit 502 can apply a DC voltage from −200 V to +200 V to the seal roller 359.

  The image forming apparatus 1 further includes a transfer control unit 503 and a transfer bias application unit 504. The transfer control unit 503 controls the transfer bias application unit 504 to apply a transfer bias to the transfer roller 126. The toner image is transferred onto the sheet from the cylindrical surface 31B of the photosensitive drum 31 by the transfer bias. The transfer control unit 503 controls the transfer bias applying unit 504 to apply a transfer reverse bias to the transfer roller 126 during the cleaning operation of the transport belt 180. Due to the reverse transfer bias, the toner attached on the conveyance belt 180 is attached again to the cylindrical surface 31 </ b> B of the photosensitive drum 31. The transfer bias application unit 504 is a power source for applying the bias to the transfer roller 126.

  In order for the cleaning device 35 to properly collect the toner and paper dust adhering to the cylindrical surface 31B of the photosensitive drum 31, the bias controller 501 applies a bias having a polarity opposite to the polarity of the toner to the seal roller 359. Apply. In the present embodiment, the toner is positively charged as the normal charging polarity. FIG. 8 is a diagram illustrating the polarity of the bias applied to the seal roller 359 during the operation of the image forming apparatus 1. In FIG. 8, when the bias applied to the seal roller 359 is negative, the bias controller 501 applies a −200 V DC voltage to the seal roller 359. When the bias applied to the seal roller 359 is positive, the bias control unit 501 applies a +200 V DC voltage to the seal roller 359.

  In FIG. 8A, “during printing” means that image formation is performed in the image forming apparatus 1, and in particular, a toner image is transferred from the cylindrical surface 31B of the photosensitive drum 31 to the sheet in the transfer nip portion TP. Means. In this case, in the area A of the photosensitive drum 31 before transfer (hereinafter referred to as “A on the drum before transfer”), the toner has a positive polarity which is a normal polarity. Then, a negative transfer bias is applied to the transfer roller 126 by the bias applying unit 502. As a result, the positive toner is transferred onto the sheet conveyed to the transfer roller 126 side, that is, the transfer nip portion TP. The toner remaining on the cylindrical surface 31B of the photosensitive drum 31 without being transferred to the sheet in the transfer nip portion TP is also in the region B of the photosensitive drum 31 after transfer (hereinafter referred to as B on the post-transfer drum). Has a positive polarity. The bias controller 501 applies a minus (−200 V) bias to the seal roller 359. As a result, the toner that enters the cleaning device 35 is attracted to the seal roller 359 as the photosensitive drum 31 rotates. Therefore, the toner is prevented from leaking from the cleaning device 35 to the transfer nip portion TP side.

  8B indicates that the sheet is not present in the transfer nip portion TP when the image is formed in the image forming apparatus 1 (between sheets). Also in this case, the bias control unit 501 applies a negative bias to the seal roller 359 in order to attract the toner adhering to the cylindrical surface 31B of the photosensitive drum 31 (on the post-transfer drum B).

  On the other hand, (C) toner band in FIG. 8 refers to the photosensitive drum 31 from the developing device 124 using a period during which no image is formed on the sheet in order to suppress the deterioration of the toner in the developing device 124. This means a mode in which toner is forcibly consumed toward. An electrostatic latent image for toner consumption is formed on the cylindrical surface 31 </ b> B of the photosensitive drum 31, and toner is consumed from the developing device 124. Then, new toner is replenished to the developing device 124 from the toner container 125 (FIG. 2), so that deterioration of the toner in the developing device 124 is suppressed. When this toner band is formed on the cylindrical surface 31B of the photosensitive drum 31, no sheet is conveyed to the transfer nip portion TP. Therefore, a transfer reverse bias having a reverse polarity to the normal transfer bias is applied to the transfer roller 126 by the transfer control unit 503. That is, a positive bias is applied to the transfer roller 126. As a result, most of the positive polarity toner that reaches the transfer nip portion TP is transported on the cylindrical surface 31B of the photosensitive drum 31 without being moved to the transport belt 180 side, and reaches the cleaning device 35. Then, a negative bias is applied to the seal roller 359 by the bias controller 501, whereby the toner is attracted from the cylindrical surface 31 </ b> B of the photosensitive drum 31 to the seal roller 359 side. Alternatively, the toner that continues to adhere to the cylindrical surface 31B of the photosensitive drum 31 is scraped off from the cylindrical surface 31B by the polishing roller 353 or the cleaning blade 351.

  As described above, when the toner band is formed (C), the toner carried on the cylindrical surface 31B of the photosensitive drum 31 is conveyed to the transfer nip portion TP without a sheet interposed in the transfer nip portion TP. Is done. At this time, a reverse transfer bias is applied to the transfer roller 126, but a part of the toner may adhere to the surface of the conveyance belt 180.

  Thus, the toner adhering to the conveyance belt 180 circulates on the conveyance belt 180 and then reaches the transfer nip portion TP again. At this time, if the sheet is conveyed to the transfer nip portion TP along with image formation, the toner adheres to the back surface of the sheet. As a result, the back surface of the sheet becomes dirty. It should be noted that the toner adhering to the conveying belt 180 is mixed with toner that is reversely charged to a polarity opposite to the normal charging polarity when passing through the transfer nip portion TP. For this reason, in this embodiment, the belt cleaning operation ((D) in FIG. 8) is performed using the time during which the image forming operation is not performed. FIG. 9 is a schematic diagram illustrating a state of bias applied to the seal roller 359 during the belt cleaning operation.

  Referring to FIG. 8, in the belt cleaning operation, the reversely charged toner (minus) is collected from the conveying belt 180 (D1) (reversely charged toner collecting mode), and the positively charged toner (plus) is collected from the conveying belt 180. Mode (D2). As shown in FIG. 9, in this embodiment, the mode for collecting the reversely charged toner and the positively charged toner is alternated according to one rotation of the conveyor belt 180 while the conveyor belt 180 is rotated a plurality of times. Is set. When the reversely charged toner is collected from the conveyance belt 180 (D1), a negative bias is applied to the transfer roller 126 by the transfer control unit 503. As a result, the reversely charged toner on the conveyance belt 180 is moved to the cylindrical surface 31B side of the photosensitive drum 31 having a higher potential than the transfer roller 126. At this time, a positive bias is applied to the seal roller 359 by the bias controller 501. Therefore, the reversely charged toner that has entered the cleaning device 35 is attracted to the seal roller 359, so that the reversely charged toner is prevented from leaking from the cleaning device 35. On the other hand, when the positively charged toner is collected from the conveyance belt 180 (D2), a positive bias is applied to the transfer roller 126 by the transfer control unit 503. As a result, the positively charged toner on the conveyance belt 180 is moved to the cylindrical surface 31B side of the photosensitive drum 31 having a lower potential than the transfer roller 126. At this time, a negative bias is applied to the seal roller 359 by the bias controller 501. Accordingly, since the positively charged toner that has entered the cleaning device 35 is attracted to the seal roller 359, the positively charged toner is prevented from leaking from the cleaning device 35.

  As described above, according to the present embodiment, the seal roller 359 is disposed on the upstream side in the rotation direction of the cylindrical surface 31 </ b> B of the photosensitive drum 31 with respect to the polishing roller 353 of the cleaning device 35. The seal roller 359 is disposed on the upstream side in the rotation direction of the cleaner housing 35 </ b> H, and is in contact with the cylindrical surface 31 </ b> B of the photosensitive drum 31. The seal roller 359 seals between the cleaner housing 35H and the photosensitive drum 31, and prevents toner from leaking from the cleaner housing 35H. The seal roller 359 is rotationally driven at a constant speed with the cylindrical surface 31B of the photosensitive drum 31 or a slightly higher speed than the cylindrical surface 31B. For this reason, the toner and paper powder conveyed on the cylindrical surface 31 </ b> B of the photosensitive drum 31 from the transfer nip portion TP toward the cleaning device 35 are smoothly carried into the cleaning device 35.

  Further, in the above embodiment, a bias having a polarity opposite to the polarity of the toner collected by the cleaning device 35 is applied to the seal roller 359. For this reason, the toner collected in the cleaning device 35 can be attracted to the seal roller 359 side. As a result, the toner is effectively prevented from leaking downward from the cleaning device 35 (to the transfer nip portion TP). Therefore, the sheet is suppressed from being soiled by the toner in the transfer nip portion TP.

  Further, in the above embodiment, the scraping member 360 is brought into contact with the seal roller 359. For this reason, excessive toner is prevented from being accumulated on the peripheral surface of the seal roller 359. Therefore, the toner is suppressed from dropping from the peripheral surface of the rotationally driven seal roller 359 to the cylindrical surface 31B of the photosensitive drum 31 upstream of the seal roller 359 in the rotation direction. Further, by cleaning the surface of the seal roller 359, the adhesion between the seal roller 359 and the cylindrical surface 31B is improved, and the sealing function (seal function) of the seal roller 359 is stably maintained.

  The cleaning device 35, the drum unit 31H including the cleaning device 35, and the image forming apparatus 1 according to the embodiment of the present invention have been described above. However, the present invention is not limited to this, and for example, the following modified embodiment is provided. Can be taken.

  (1) In the above embodiment, the polishing roller 353 and the cleaning blade 351 are disposed on the downstream side in the rotation direction of the photosensitive drum 31 with respect to the seal roller 359. However, the present invention is not limited thereto. It is not limited. The polishing roller 353 may be a cleaning roller that cleans the surface of the photosensitive drum 31. In this case, the cleaning blade 351 may be disposed downstream of the cleaning roller in the rotation direction of the photosensitive drum 31, or the cleaning blade 351 may not be disposed.

  (2) In the above embodiment, the seal roller 359 is rotationally driven by a driving unit (not shown) at the same speed as the cylindrical surface 31B of the photosensitive drum 31 or slightly faster than the cylindrical surface 31B. It explained in the aspect. The present invention is not limited to this. The seal roller 359 may be rotated in accordance with the cylindrical surface 31B of the photosensitive drum 31. In this case, the seal roller 359 may be rotated by the contact pressure between the cylindrical surface 31B of the photosensitive drum 31 and the peripheral surface of the seal roller 359. Further, a mode in which a drive transmission gear (not shown) is disposed between the photosensitive drum 31 and the seal roller 359 may be employed. Note that when the seal roller 359 slips with respect to the cylindrical surface 31 </ b> B of the photosensitive drum 31, toner or paper powder is sandwiched between the seal roller 359 and the photosensitive drum 31. For this reason, it is more preferable that the above-described drive transmission gear is provided and the driving force is reliably transmitted.

  (3) In the above embodiment, the cleaning device 35 including the seal roller 359 has been described as being disposed in the drum unit 31H, but the present invention is not limited to this. The cleaning device 35 including the seal roller 359 may be individually attached to the image forming apparatus 1.

30 Image forming unit 31 Photosensitive drum (image carrier)
31H drum unit (image carrier unit)
32 Charging device 321 Charging roller 322 Charging cleaning roller 32H Charging housing 33 Developing device 34 Transfer roller (transfer member)
35 Cleaning device 35H Cleaner housing (housing)
35H1 Housing rear wall (standing wall)
351 Cleaning blade 351H Blade holder 351B First fixed screw 352 Conveying screw 353 Polishing roller (rotating member)
354 Scraper 355 Scraper holder 356 Upper seal 359 Seal roller 360 Scraping member 501 Bias control unit (bias control means)
502 Bias application unit (bias application means)
503 Transfer control unit (transfer bias control means)
504 Transfer bias applying unit (transfer bias applying means)

Claims (10)

A cleaning device that is disposed above an image carrier having a rotation shaft and a cylindrical surface that rotates in one direction around the rotation shaft and carries a toner image, and that cleans the cylindrical surface,
A housing,
In a cross-sectional view orthogonal to the rotation axis, the rotation surface is in contact with the cylindrical surface above the rotation axis, and is driven to rotate in the same direction as the image carrier at the contact position. A rotating member for collecting the toner adhering to
A circumferential surface disposed in the housing and in contact with the cylindrical surface on the upstream side in the rotational direction of the image carrier above the rotating member in the cross-sectional view, A seal roller that is rotationally driven in the same direction as the cylindrical surface at the contact portion;
Bias applying means for applying a bias to the seal roller;
A cleaning device comprising: Further comprising bias control means for controlling the bias applied to the seal roller;
The cleaning device according to claim 1, wherein the bias control unit applies a bias having a polarity opposite to a normal charging polarity of the toner to the seal roller.   A scraping member that comes into contact with a peripheral surface of the seal roller along a direction in which the rotation shaft extends is provided downstream of the contact portion in the rotation direction of the seal roller. Item 3. The cleaning device according to Item 1 or 2. The housing has a standing wall arranged to face the rotating member,
The cleaning apparatus according to claim 1, wherein the seal roller is disposed at a lower end portion of the standing wall.   5. A cleaning blade that contacts the cylindrical surface on the downstream side in the rotation direction of the image carrier relative to the rotating member and further removes toner adhering to the image carrier. The cleaning device according to any one of the above. The rotating member is a polishing roller that polishes deposits attached to the cylindrical surface of the image carrier,
The cleaning apparatus according to claim 1, further comprising a regulating member that abuts on the rotating surface of the polishing roller and regulates an amount of toner adhering to the rotating surface. A cleaning device according to any one of claims 1 to 6,
An image carrier unit comprising: the image carrier disposed to face the seal roller. A cleaning device according to claim 1;
The image carrier disposed to face the seal roller;
A developing device for supplying toner to the cylindrical surface of the image carrier;
A transfer member that is rotationally driven to face the image carrier and transfers the toner image from the image carrier to a sheet;
A transfer bias applying means for applying a transfer bias to the transfer member;
Transfer bias control means for controlling the transfer bias applied to the transfer member,
The transfer bias control unit includes a reverse charge toner recovery mode in which a bias having a polarity opposite to a normal charging polarity of the toner is applied to the transfer member;
The image forming apparatus, wherein the bias control unit applies a bias having the same polarity as the normal charging polarity to the seal roller in accordance with the reversely charged toner recovery mode of the transfer bias control unit. A cleaning device according to any one of claims 1 to 6,
The image carrier disposed to face the seal roller;
A developing device for supplying toner to the cylindrical surface of the image carrier;
An image forming apparatus comprising: A sheet conveying path that conveys a sheet from the lower side to the upper side, facing the image carrier,
A transfer member that is in contact with the cylindrical surface of the image carrier and forms a transfer nip portion for transferring the toner image from the image carrier to the sheet;
The image carrier is rotationally driven from below to above in the transfer nip portion,
The image forming apparatus according to claim 9, wherein the cleaning member is in contact with the cylindrical surface of the image carrier between the transfer nip portion and a position immediately above the rotation shaft.

Images