JP2011013349A - Cleaning device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device capable of performing effective cleaning operation while preventing or suppressing an increase in toner consumption, and an image forming apparatus.SOLUTION: The cleaning device is provided with a plate roll 12 for forming a reservoir space of toner scraped by a cleaning blade 11. In an image formation period, a roller controller rotates a cleaning roller in an opposite direction to a rotating direction of a photoreceptor drum, thereby allowing the cleaning roller to carry the toner reservoired in the reservoir space, and perform the cleaning operation on a circumferential surface of the photoreceptor drum 2 by using toner. In a non-image-formation period, if an ejection amount of toner detected by a toner ejection amount detection part is equal to or above a predetermined threshold, the cleaning roller is rotated in a reverse direction to the rotating direction of the cleaning roller in the image formation period, thereby discharging the toner reservoired in the reservoir space to the outside.

Description

  The present invention belongs to a technical field of an image forming apparatus such as a printer, a copier, or a multifunction machine, and particularly relates to a cleaning technique for removing deposits such as toner remaining on an image carrier.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, a photosensitive drum is widely used as an image carrier. In the image forming apparatus using the photosensitive drum, the peripheral surface of the photosensitive drum is uniformly charged to a predetermined potential by a charging device, and an LED of an exposure device is applied to the peripheral surface of the photosensitive drum based on image data. By irradiating light or the like, the potential is partially attenuated to form an electrostatic latent image corresponding to the original image, and this electrostatic latent image is developed by a developing device, so that the peripheral surface of the photosensitive drum is developed. A toner image is formed, and the toner image is transferred to the sheet when the sheet passes through a transfer region formed by bringing the photosensitive drum and the transfer member into contact with or in close proximity to each other. .

  In this type of image forming apparatus, after a toner image is transferred to a sheet, some toner may remain on the peripheral surface of the photosensitive drum without being transferred to the sheet. The residual toner adhering to the peripheral surface of the photosensitive drum becomes an obstacle to the next new image formation, and therefore the photosensitive drum needs to be cleaned. The cleaning method used here includes, for example, a method in which a rotating member such as a cleaning roller or a rotating brush is pressed against the peripheral surface of the photosensitive drum to move and collect residual toner on the rotating member, or a photosensitive member. A method of scraping residual toner by bringing a cleaning blade into contact with the peripheral surface of the drum, or a cleaning method combining these methods is widely known.

  On the other hand, when an amorphous silicon photoconductor is used as the photoconductor, discharge products generated by the discharge of the charging device are likely to adhere to the peripheral surface. If this discharge product absorbs moisture, the electrical resistance of the peripheral surface of the photoreceptor may be reduced, causing a problem of image flow that disturbs the electrostatic latent image. For this reason, a method is known in which a small amount of abrasive is added to the toner, the toner is carried on the peripheral surface of the cleaning roller, and the discharge product adhering to the peripheral surface of the photosensitive member is polished by this toner to be cleaned. It has been.

  The following Patent Documents 1 and 2 relate to the photosensitive drum cleaning technology, and use a means for switching the rotation direction of the polishing roller and a cleaning blade to remove discharge products adhering to the surface of the photosensitive drum. Proposed.

  In Patent Document 1 below, a polishing mode is provided in which the polishing roller is disposed upstream and above the rotation direction of the image carrier relative to the cleaning blade, and the rotation direction of the polishing roller is used to polish the surface of the image carrier. In this case, the rotation direction of the image carrier is set to be the same as the rotation direction of the image carrier, so that the nip outlet between the polishing roller and the photosensitive drum is positioned above the nip portion to form a toner reservoir there. It has been proposed that the surface of the photosensitive drum is polished using a toner that is present and that the rotation direction of the image carrier is different from that in a mode other than the polishing mode.

  In Patent Document 2 below, even if there is a variation in the image area ratio in each part of the peripheral surface of the photosensitive drum, the rotation of the photosensitive drum is performed for the purpose of effectively removing foreign matters adhering to the peripheral surface. Until the time reaches a predetermined time, the number of dots to be written is counted for each block obtained by dividing the photosensitive drum into 6 parts in the main scanning direction, and the image area ratio for each block is obtained. Regarding the block, a technique is disclosed in which an electrostatic latent image having a predetermined toner consumption pattern is formed on a photosensitive member, the toner is adhered by a developing unit, and the toner is forcibly input to a cleaning unit.

JP 2008-146034 A JP 2006-126753 A

  In the image forming apparatus according to Patent Document 1, the rotation direction of the polishing roller in a mode other than the polishing mode is different from the rotation direction of the image carrier. However, if the rotation direction of the polishing roller in a mode other than the polishing mode is simply different from the rotation direction of the image carrier, the toner in the toner pool is discharged to the outside from the nip outlet, and the toner in the toner pool is removed. In some cases, the amount of toner required for cleaning may be lost. In order to compensate for the shortage of toner, it is conceivable to supply toner from the developing unit, but this causes an increase in toner consumption.

  In the image forming apparatus according to Patent Document 2 described below, toner for supplying a non-printed portion of toner for preventing poor polishing and preventing hair fall and clogging due to reverse rotation of the cleaning brush is problematic. It becomes. Further, in order to suppress toner consumption while performing the reverse rotation operation, when the toner is not supplied, sufficient polishing is not performed and an image defect occurs.

  The present invention has been made in view of such circumstances, and provides a cleaning device and an image forming apparatus capable of performing an effective cleaning operation while preventing or suppressing an increase in toner consumption. Objective.

  According to a first aspect of the present invention, there is provided a cleaning blade that removes toner adhering to the peripheral surface from the peripheral surface by contacting the peripheral surface of the image bearing drum, and a peripheral surface of the image bearing drum by the cleaning blade. A toner receiving member that forms a toner storing portion that receives and stores the toner removed from the toner cartridge at a predetermined position, and a peripheral surface that is in sliding contact with the peripheral surface of the image bearing drum, and is in sliding contact with the peripheral surface of the image supporting drum. The circumferential surface of the cleaning roller that contacts the toner in the toner storage portion and carries the toner, and the rotational direction of the cleaning roller. The circumferential surface of the cleaning roller is in contact with the image bearing drum. A roller control unit that switches between a forward rotation direction that moves in the same direction as the circumferential surface of the roller and a reverse rotation direction that is the reverse direction to the forward rotation direction. The rotating roller rotates the cleaning roller in the forward rotation direction during an image forming period in which a toner image is formed on the image bearing drum, thereby causing the cleaning roller to perform an operation of slidingly contacting the peripheral surface of the image bearing drum. In the non-image forming period other than the image forming period, by rotating the cleaning roller in the reverse direction, the cleaning roller performs a discharging operation for discharging the toner in the toner storage unit to the outside of the toner storage unit. It is a cleaning device.

  According to the present invention, the toner receiving member is provided, the toner removed from the peripheral surface of the image bearing drum by the cleaning blade is received and stored at a predetermined position by the toner receiving member, and the stored toner is stored for cleaning. Since the toner is carried on the peripheral surface of the cleaning roller, the image carrying drum can be cleaned (the removal operation) during the image forming period without requiring new toner each time cleaning is performed. it can.

  On the other hand, during the non-image forming period, the cleaning roller is rotated in the reverse direction so that the toner in the toner reservoir is carried on the cleaning roller, and the toner is discharged out of the toner reservoir. As a result, the toner in the toner reservoir becomes excessive and a large amount of toner accumulates above the contact portion between the image carrier drum and the cleaning roller. It is possible to prevent or suppress the occurrence of discharge breakdown between the two.

  The toner receiving member is installed from a peripheral surface of the cleaning roller to a radially outer side in a cross section of the roller via a predetermined gap as in the invention according to claim 2, and the image is formed by the cleaning blade. It is assumed that the toner removed from the carrying drum is stored.

  According to a third aspect of the present invention, there is provided image data for the image bearing drum, a charging unit that uniformly charges the circumferential surface of the image bearing drum, and the circumferential surface of the image bearing drum after the charging operation by the charging unit. An exposure unit that forms an electrostatic latent image by performing an exposure operation based on the image, a developing unit that visualizes the electrostatic latent image formed on the peripheral surface of the image carrying drum with toner, and a peripheral portion of the image carrying drum. The transfer part which transfers the toner image formed on the surface to a predetermined recording medium, and the deposits attached to the peripheral surface of the image carrying drum after the transfer by the transfer part are removed. An image forming apparatus including the cleaning device.

  According to this invention, in the image forming apparatus, the effect of the invention according to claim 1 or 2 can be obtained.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the image forming apparatus further includes an input operation unit for inputting an instruction to form an image based on the image data on the predetermined recording medium. The image forming unit supplies a toner for forming an image on the predetermined recording medium to the image bearing drum during an image forming period, and the image bearing unit uses the toner held by the developing unit as an unnecessary toner. When the instruction is input from the input operation unit, the roller controller discharges to the image carrier drum by the discharge operation during the image forming period corresponding to the instruction. When the discharge amount of the unnecessary toner is compared with a predetermined threshold for the discharge amount, and the discharge amount is larger than the threshold, the non-image form immediately after the end of the image forming period based on the instruction In the period, is the discharge operation of the toner of the cleaning roller is rotated in the reverse direction the toner storage shall be carried out on the cleaning roller.

  According to this invention, when the supply amount of the unnecessary toner supplied to the image bearing drum in the ejection operation during the image forming period based on the image forming instruction by the input operation unit is larger than the threshold, the image based on the instruction In the non-image forming period immediately after the end of the forming period, the cleaning roller is rotated in the reverse direction to cause the cleaning roller to perform the discharging operation of the toner in the toner storing unit. An excessive amount of toner can be prevented or suppressed.

  With respect to the predetermined threshold value, for example, if the rotation time of the cleaning roller that rotates in the discharge operation scheduled to be performed in the non-image forming period is long, the toner discharged from the toner storage unit by the discharge operation The toner amount in the toner storage portion is depleted unless the toner storage allowable amount in the toner storage portion is set large as the rotation time of the cleaning roller increases as the amount of the cleaning roller increases. As in the first aspect of the invention, it may be set according to the rotation time of the cleaning roller related to the discharge operation scheduled to be performed in the non-image forming period.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the third to fifth aspects, the image bearing drum does not rotate while the cleaning roller performs the discharging operation. It is.

  If the image bearing drum is continuously rotated while the cleaning roller is performing the discharging operation, the torque acting on the surface of the image bearing drum becomes excessive, and a discharge occurs between the toner and the image bearing drum. The peripheral surface of the image bearing drum may be damaged, but the image bearing drum should not be rotated while the cleaning roller is performing the discharging operation as in the present invention. Thus, it is possible to prevent or suppress the occurrence of such a problem.

  According to the present invention, it is possible to prevent the occurrence of discharge breakdown between the toner and the image bearing drum due to the accumulation of a large amount of toner on the contact portion between the image bearing drum and the cleaning roller. While being suppressed, the image bearing drum can be cleaned during the image forming period without supplying new toner.

1 is a diagram schematically showing an internal configuration of an embodiment of an image forming apparatus according to the present invention. It is a figure which shows the structure of a cleaning unit. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus according to an exemplary embodiment. It is a flowchart which shows the process of a control part.

  Hereinafter, an embodiment of an image forming apparatus including a cleaning device according to the present invention will be described with reference to the drawings. FIG. 1 is a front view showing an example of an image forming apparatus according to the present invention.

  As shown in FIG. 1, the image forming apparatus 1 has a cylindrical photosensitive drum 2 whose peripheral surface is made of amorphous silicon as an image bearing drum. 3), a developing device (corresponding to the developing unit) 4, a transfer roller (corresponding to the transferring unit) 5 as an example of a transfer body, a cleaning unit 6, and a static eliminator 7 are arranged along the rotation direction of the photosensitive drum 2. Has been. The developing device 4 holds toner. The toner has a configuration in which an abrasive such as silica, alumina, zirconia, titania or the like is attached to the peripheral surface of the binder resin as mother particles. In addition to the binder resin, the toner contains, for example, about 30% pigment, wax, charge control agent, and the like.

  The image forming operation by the image forming apparatus 1 is performed as follows. After the peripheral surface of the photosensitive drum 2 is uniformly charged to a predetermined potential by the charger 3, exposure is performed by irradiating the peripheral surface of the photosensitive drum 2 with laser light 9 according to image data by an unillustrated exposure unit. As a result, an electrostatic latent image is formed on the photosensitive drum 2. Thereafter, the electrostatic latent image on the photosensitive drum 2 is developed by the developing device 4 into a toner image, and the toner image on the photosensitive drum 2 is transferred to a transfer material, for example, a recording paper 12 by the transfer roller 5. . At the time of this transfer, a transfer bias electric field is applied between the photosensitive drum 2 and the transfer roller 5 so that the charged toner is smoothly moved to the recording paper 12 as a recording medium. The recording medium includes a member that temporarily holds a toner image, such as an intermediate transfer member.

  The toner remaining on the photosensitive drum 2 after the transfer is removed by the cleaning unit 6. Thereafter, the residual potential on the photosensitive drum 2 is erased by the static eliminator 7. Then, it is charged again by the charger 3, and the above image forming process is repeated.

  On the other hand, the recording paper 12 is unwound from the paper cassette 13 and conveyed along the conveying line 14 and is sent between the photosensitive drum 2 and the transfer roller 5. The toner image is transferred, and then discharged to the discharge tray 16 through the fixing unit 15. A registration roller pair 17 is provided on the upstream side of the transfer roller 5 in the transport line 14. The registration paper pair 17 abuts against the registration roller pair 17 and is temporarily stopped to form an image on the photosensitive drum 2. In synchronization with the timing, the registration roller pair 17 is driven to feed the recording paper P toward the transfer nip between the photosensitive drum 2 and the transfer roller 5.

  In the image forming apparatus 1 configured as described above, the transfer roller 5 is disposed above the photosensitive drum 2, and the conveyance line 14 is provided so as to pass between the photosensitive drum 2 and the transfer roller 5. ing. A cleaning unit 6 is provided below the transport line 14 and downstream of the transfer roller 5 in the rotation direction of the photosensitive drum 2.

  FIG. 2 is an enlarged view showing the configuration of the cleaning unit 6.

  The cleaning unit 6 includes a cleaning roller 10, a cleaning blade 11 disposed below the cleaning roller 10, that is, a downstream side in the rotation direction of the photosensitive drum 2 when viewed from the cleaning roller 10, and the vicinity of the cleaning roller 10. A plate roll 12 (corresponding to a toner receiving member).

  The cleaning roller 10 has a cylindrical shape, and its peripheral surface slides (contacts) with the peripheral surface of the photosensitive drum 2 with a rotational axis Q parallel to the rotational axis O of the photosensitive drum 2 as a rotation center. It will rotate. The cleaning roller 10 is driven by a drive motor 20 (see FIG. 1). The drive motor 20 is configured to be rotatable in both forward and reverse directions, and the cleaning roller 10 rotates in a direction corresponding to the rotation direction of the drive motor 20. The rotation direction of the drive motor 20 is switched by, for example, a roller control unit 21 (see FIG. 3) described later that switches the voltage application direction.

  The cleaning roller 10 is made of foamed rubber, for example, and has fine irregularities on the peripheral surface. The toner adheres to the peripheral surface of the cleaning roller 10 due to the unevenness.

  The cleaning blade 11 contacts the circumferential surface of the photosensitive drum 2 at a predetermined position below the cleaning roller 10 (a position downstream in the rotation direction of the photosensitive drum 2), and toner (from the circumferential surface of the photosensitive drum 2) Residual toner) is scraped off.

  The plate roll 12 is a member for forming a toner storage space (an example of the storage unit) scraped by the cleaning blade 11. That is, the plate roll 12 has a curved surface that curves along the circumferential surface of the cleaning roller 10 through a gap of a predetermined length from the circumferential surface of the cleaning roller 10 on the radially outer side in the cross section of the cleaning roller 10. A space surrounded by the peripheral surface of the plate roll 12, the cleaning roller 10 and the photosensitive drum 2 and the cleaning blade 11 is formed as the storage space.

  When the radius of the photosensitive drum 2 is set in the range of 20 mm to 50 mm, for example, and the radius of the cleaning roller 10 is set in the range of 10 mm to 30 mm, for example, the separation between the plate roll 12 and the cleaning roller 10 is performed. The distance is set in the range of 1 mm to 5 mm, for example.

  In the cleaning unit 6, the electrostatic latent image supplied from the developing device 4 and formed on the peripheral surface of the photosensitive drum 2 is converted into a toner image by the developing device 4, and this toner image is transferred to the recording paper P. The toner remaining on the peripheral surface of the photosensitive drum 2 without being transferred to the recording paper P is scraped off by the cleaning blade 11. The scraped toner is stored in the storage space. When the toner stored in the storage space reaches the position of the peripheral surface of the cleaning roller 10, the cleaning roller 10 carries the toner on the peripheral surface.

  Here, as indicated by an arrow B in FIG. 2, when the cleaning roller 10 rotates in the direction opposite to the rotation direction of the photosensitive drum 2 (the circumferential surface of the cleaning roller 10 is in a contact area with the photosensitive drum 2). When rotating in a direction that moves in the same direction as the circumferential surface of the photosensitive drum 2), the cleaning roller 10 supplies the carried toner to the contact portion with the photosensitive drum 2. At this time, an operation of removing the adhering matter adhering to the peripheral surface of the photosensitive drum 2 using the toner as an abrasive is performed. The rotation direction of the cleaning roller 10 at this time corresponds to the normal rotation direction.

  On the other hand, as indicated by an arrow C in FIG. 2, when the cleaning roller 10 rotates in the same direction as the rotation direction of the photosensitive drum 2 (the peripheral surface of the cleaning roller 10 is in contact with the photosensitive drum 2). When rotating in a direction moving in the direction opposite to the circumferential surface of the photosensitive drum 2), the cleaning roller 10 discharges the carried toner to the outside of the storage space as indicated by an arrow D through the contact portion. To do. The rotation direction of the cleaning roller 10 at this time corresponds to the reverse direction.

  The plate roll 12 has an upper end at a contact portion (hereinafter referred to as a nip portion) between the cleaning roller 10 and the photosensitive drum 2 in order to make the toner stored in the storage space easily adhere to the peripheral surface of the cleaning roller 10. It is preferable that it is configured to extend to a height position equivalent to or higher than that. Here, the height refers to a height in a direction perpendicular to the ground.

  FIG. 3 is a block diagram showing an example of the electrical configuration of the image forming apparatus 11 shown in FIG. As shown in FIG. 3, the image forming apparatus 1 includes an input operation unit 18 and a control in addition to the photosensitive drum 2, the charger 3, the developing device 4, the transfer roller 5, the cleaning unit 6, and the static eliminator 7. The unit 21 is provided.

  Although not described in detail, the input operation unit 18 is a numeric key for inputting the number of prints, a start button for starting a print operation, a stop for the print operation, and a stop for canceling the input operation. / Clear button, a reset button for setting various settings to an initial state or a standard operation state, and the like.

  The control unit 21 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) that stores a predetermined control program, and a RAM (Random Access Memory) that temporarily stores data. The above-described photosensitive drum 2, charger 3, developing device 4, transfer roller 5, cleaning unit 6 and static eliminator 7 are connected to the control unit 21.

  The control unit 21 in this embodiment functions as a drum control unit 22, a roller control unit 23, and a toner discharge amount detection unit 24.

  The drum control unit 22 controls the rotation operation of the photosensitive drum 2. In this embodiment, when the image forming operation is performed by the image forming apparatus 1, the photosensitive drum 2 is rotated in advance. When the image forming apparatus 1 does not perform the image forming operation, the rotating operation of the photosensitive drum 2 is stopped.

  The toner discharge amount detection unit 24 detects the discharge amount of unnecessary toner discharged from the developing device 4 to the photosensitive drum 2 during the image formation period.

  The developing device 4 includes a developing roller and a toner container (not shown), and the toner in the toner container is supplied to the peripheral surface of the developing roller when an image forming operation is performed. Here, a part of the toner supplied to the peripheral surface of the developing roller is supplied to the photosensitive drum 2 from the developing roller and used for image formation, and the rest is not used for image formation (development). The toner remains on the developing roller (not shown) of the developing device 4 (not supplied from the roller to the photosensitive drum 2). For example, when an image forming operation with a low printing rate is performed, the amount of toner remaining on the developing roller is particularly large. If the toner remaining in this manner is left attached to the developing roller, it does not have the required charge amount, and the amount of toner supplied from the developing roller to the photosensitive drum 2 is set from the set value at the next and subsequent image formation. As a result, the density of the image may be adversely affected.

  Therefore, in the present embodiment, the toner discharge amount detection unit 24 forms a predetermined timing in the image formation period, for example, the first image every time an image formation instruction is input by the input operation unit (start button). Development is performed at a timing before the image forming operation is performed, or when an image is formed on a plurality of recording sheets, from when the image forming operation for one sheet is completed to when the image forming operation is started for the next sheet. The toner adhering to the peripheral surface of the roller is discharged from the developing device 4 to the photosensitive drum 2, and the discharged toner is collected in the storage space by using the cleaning blade 11 so as to be used as cleaning toner. Yes. In the following description, this toner is referred to as unnecessary toner to distinguish it from the toner remaining on the photosensitive drum 2 at the time of the transfer operation. The toner discharge amount per discharge operation is predetermined, and the number of discharges is set according to the printing rate of the image to be formed. The toner discharge amount detection unit 24 detects the discharge amount of unnecessary toner discharged from the developing device 4 to the photosensitive drum 2 during each image forming period.

  The roller control unit 23 controls the rotation operation of the cleaning roller 10. When the image forming process is performed, the roller control unit 23 rotates the cleaning roller 10 in a direction opposite to the rotation direction of the photosensitive drum 2 (the circumferential surface of the cleaning roller 10 and the circumferential surface of the photosensitive drum 2). The cleaning roller 10 is rotated in such a direction as to move in the same direction as the peripheral surface of the photosensitive drum 2 at the contact portion of the photosensitive drum 2.

  During the image formation, the peripheral speed of the photosensitive drum 2 is set, for example, in a range of 75 mm / second to 400 mm / second, while the peripheral speed of the cleaning roller 10 is set to the peripheral speed of the photosensitive drum 2. On the other hand, the peripheral speed is set to about 0.6 to 1.5 times.

  As a result, when the toner stored in the storage space is carried, the cleaning roller 10 performs a removing operation for removing the deposits on the peripheral surface of the photosensitive drum 2 using the toner.

  On the other hand, when the image forming process is not performed (non-image forming period), the roller control unit 23 controls the cleaning roller 10 according to the toner discharge amount detected by the toner discharge amount detection unit 24. Is different.

  In other words, the roller control unit 23 does not rotate the cleaning roller 10 when the toner discharge amount detected by the toner discharge amount detection unit 24 is smaller than a predetermined threshold value.

  On the other hand, when the toner discharge amount detected by the toner discharge amount detection unit 24 is equal to or greater than a predetermined threshold during the non-image formation period, the roller control unit 23 causes the cleaning roller 10 to move during the image formation. The cleaning roller 10 is rotated in the direction opposite to the rotation direction (direction indicated by arrow C in FIG. 2). This is due to the following reason.

  The toner stored in the storage space includes the above-described unnecessary toner as well as the residual toner that remains on the peripheral surface of the photosensitive drum 2 without being transferred. If the amount of the unnecessary toner is excessive, the amount of toner in the storage space becomes excessive, and as a result, the toner pool is generated at the upper part (upper nip) of the contact portion between the photosensitive drum 2 and the cleaning roller 10. If the amount of accumulated toner in this portion increases, there is a risk that discharge breakdown will occur between this toner and the photosensitive drum 2. Accordingly, the cleaning roller 10 is rotated in the direction opposite to the rotation direction of the cleaning roller 10 at the time of image formation (the direction indicated by the arrow C in FIG. 2), and the toner accumulated in the storage space is discharged to the outside. The amount of toner at the upper part of the region is controlled.

  FIG. 4 is a flowchart showing processing by the control unit 21.

  As shown in FIG. 4, when an image forming operation instruction is input by the input operation unit 18 (YES in step # 1), the drum control unit 22 moves the photosensitive drum 2 in a predetermined direction (arrow A in FIG. 2). Further, the roller control unit 23 rotates the cleaning roller 10 forward at a predetermined speed (rotates in the direction opposite to the rotation direction of the photosensitive drum 2) (step # 2). Thereby, the adhering matter adhering to the peripheral surface of the photosensitive drum 2 by the image forming operation can be removed from the peripheral surface of the photosensitive drum 2.

  The roller controller 23 performs the process of step # 2 until the image forming operation is completed (NO in step # 3). When the image forming operation is completed (YES in step # 3), the roller control unit 23 performs the process until the operation is completed. It is determined whether or not the amount of discharged unnecessary toner is equal to or greater than a predetermined threshold (step # 4). If the amount of unnecessary toner discharged is equal to or greater than the threshold (YES in step # 4). ) The cleaning roller is reversely rotated at a predetermined speed for a predetermined time (step # 5). As a result, due to the excessive amount of toner in the storage space, a discharge breakdown occurs between the toner accumulated in the upper part (upper nip) of the contact portion between the photosensitive drum 2 and the cleaning roller 10 and the photosensitive drum 2. Can be prevented or suppressed.

  As described above, in this embodiment, the plate roll 12 is provided, and the toner remaining on the peripheral surface of the photosensitive drum 2 without being transferred or the toner remaining in the developing device 4 without being used for the image forming operation is used as unnecessary toner. Since the toner discharged to the photosensitive drum 2 is scraped off by the cleaning blade 11, and the scraped toner is received and collected by the plate roll 12, the amount of toner supplied to the toner storage space is small and low. Even when an image forming process with a printing rate (for example, a printing rate of about 2% or less) is performed, toner is reliably supplied to the peripheral surface of the cleaning roller 10 to prevent the occurrence of cleaning failure due to toner shortage or Can be suppressed.

  In addition, since the cleaning roller 10 is reversely rotated during the non-image forming period to discharge the toner accumulated in the storage space to the outside, the toner accumulated in the upper part of the nip and the photosensitive drum 2 are used. It is possible to prevent or suppress the occurrence of discharge breakdown.

  In this case, the following modifications may be employed instead of or in addition to the embodiment.

  (1) In the first embodiment, when the amount of unnecessary toner discharged from the developing device 4 to the photosensitive drum 2 is equal to or more than a predetermined threshold in the non-image forming period, the cleaning roller 10 is reversed. The toner in the storage space rotates to be discharged to the outside, but the storage space is generated by reversely rotating the cleaning roller 10 during the non-image forming period regardless of the discharge amount (without making a determination regarding the discharge amount). The toner may be discharged to the outside.

  (2) In the first embodiment, the threshold for the discharge amount of unnecessary toner is set to a fixed value regardless of the execution time of the reverse rotation operation (operation for discharging the toner to the outside) by the cleaning roller 10. If the rotation time of the cleaning roller 10 related to the discharging operation is long, the amount of toner discharged from the storage space by the discharging operation increases. Therefore, unless the toner storage allowable amount in the storage space is set to be large, the cleaning toner in the storage space is exhausted. Therefore, the threshold value may be set according to the rotation time of the cleaning roller 10 related to the discharge operation scheduled to be performed in the non-image forming period.

  For example, the threshold value may be increased in proportion to the rotation time of the cleaning roller 10, or a plurality of stages may be set for the rotation time of the cleaning roller 10, and the rotation time of each cleaning roller 10 may be set. The longer the stage, the larger the threshold value may be set.

  (3) In the first embodiment, the rotation operation of the photosensitive drum 2 at the time of non-image formation is stopped, but it may be continuously rotated. However, if the rotation is continued at the time of image formation, an excessive torque acts on the photosensitive drum 2 when the cleaning roller 10 performs a rotation operation related to the discharging operation, and the peripheral surface of the photosensitive drum 2 and the cleaning roller 10. Therefore, it is preferable to stop the rotating operation of the photosensitive drum 2 as in the first embodiment.

  (4) In the first embodiment, the presence / absence of the toner discharge operation by the cleaning roller 10 is determined according to the discharge amount of the unnecessary toner discharged onto the photosensitive drum 2, but the present invention is not limited to this. First, a storage amount detection unit that detects a storage amount of toner in the storage space is provided, and whether or not the toner is discharged by the cleaning roller 10 is determined according to the storage amount of toner detected by the storage amount detection unit. It may be.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photosensitive drum 3 Charger 4 Developing apparatus 5 Transfer roller 6 Cleaning unit 7 Static eliminator 10 Cleaning roller 11 Cleaning blade 12 Plate roll 18 Input operation part 21 Control part 22 Drum control part 23 Roller control part 24 Toner discharge Quantity detector

Claims (6)

A cleaning blade for removing toner adhering to the peripheral surface from the peripheral surface by contacting the peripheral surface of the image bearing drum;
A toner receiving member that forms a toner storage portion that receives and stores toner removed from the peripheral surface of the image bearing drum at a predetermined position by the cleaning blade;
A cleaning roller having a peripheral surface slidably contacting the peripheral surface of the image bearing drum, and a peripheral surface slidably contacting the peripheral surface of the image bearing drum contacting the toner of the toner storage unit and supporting the toner;
The rotation direction of the cleaning roller is a forward rotation direction in which the circumferential surface of the cleaning roller moves in the same direction as the circumferential surface of the image bearing drum at a contact portion with the image bearing drum, and a direction opposite to the forward rotation direction. A roller control unit that switches between a reverse direction,
The roller control unit
During the image forming period in which a toner image is formed on the image bearing drum, the cleaning roller is rotated in the forward rotation direction to cause the cleaning roller to perform an operation of slidingly contacting the peripheral surface of the image bearing drum;
Cleaning that causes the cleaning roller to discharge the toner in the toner reservoir outside the toner reservoir by rotating the cleaning roller in the reverse direction during a non-image formation period other than the image formation period. apparatus.   The toner receiving member is disposed from a peripheral surface of the cleaning roller to a radially outer side in a cross section of the roller via a predetermined gap, and stores toner removed from the image bearing drum by the cleaning blade. The cleaning device according to claim 1, wherein The image bearing drum;
A charging unit for uniformly charging the peripheral surface of the image bearing drum;
An exposure unit that forms an electrostatic latent image by performing an exposure operation based on image data on the peripheral surface of the image bearing drum after the charging operation by the charging unit;
A developing unit that visualizes the electrostatic latent image formed on the peripheral surface of the image bearing drum with toner;
A transfer unit for transferring a toner image formed on the peripheral surface of the image bearing drum to a predetermined recording medium;
An image forming apparatus comprising: the cleaning device according to claim 1 or 2 for removing deposits attached to a peripheral surface of the image bearing drum after being transferred by the transfer unit. An input operation unit for inputting an instruction to form an image based on the image data on the predetermined recording medium;
The developing unit supplies a toner for forming an image on the predetermined recording medium to the image bearing drum during an image forming period, and uses the toner held by the developing unit as an unnecessary toner. The discharge operation to discharge to the image bearing drum is performed,
When the instruction is input from the input operation unit, the roller control unit discharges unnecessary toner discharged onto the image bearing drum by the discharge operation during the image forming period corresponding to the instruction and the discharge amount. When the discharge amount is larger than the threshold, the cleaning roller is rotated in the reverse direction during the non-image forming period immediately after the end of the image forming period based on the instruction. The image forming apparatus according to claim 3, wherein the cleaning roller performs the discharging operation of the toner in the toner storage unit.   The image forming apparatus according to claim 4, wherein the predetermined threshold is set according to a rotation time of the cleaning roller related to the discharge operation scheduled to be performed in the non-image forming period.   The image forming apparatus according to claim 3, wherein the image bearing drum does not rotate while the cleaning roller performs the discharging operation.

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