JP5659688B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  As the prior art described in the publication, after the image carrier is rotated, the toner image formed on the surface thereof is transferred onto a transfer material, and then the transfer residual toner on the image carrier is removed using a cleaning blade. In an image forming apparatus that terminates the formation operation and stops the rotation of the image carrier, reverse rotation control is started after the transfer of the transfer date is stopped and before the rotation of the image carrier is stopped, and the image carrier is rotated in reverse. There is an image carrier rotation control device provided with a control means (see Patent Document 1).

  Further, as conventional techniques described in other publications, a photosensitive drum on which an electrostatic latent image is formed, a photosensitive drum rotation driving unit that rotates the photosensitive drum in the forward direction and the reverse direction, and a photosensitive drum A charging device that charges the surface, an exposure device that forms an electrostatic latent image on the surface of the charged photosensitive drum, and a developer roller that supplies toner from the developing roller to the surface of the photosensitive drum. A developing device for developing, a developing bias supplying means for supplying a developing bias potential to the developing roller, an intermediate transfer medium on which toner on the surface of the photosensitive drum is transferred, and a transfer bias supplying for supplying a transfer bias potential to the intermediate transfer medium And a cleaning device having a cleaning blade that contacts the rotating photosensitive drum and cleans the surface of the photosensitive drum. When the photosensitive drum rotates in the reverse direction, the developing device cleans the cleaning blade by rotating the photosensitive drum in reverse, and the developing device applies toner to the contact portion between the cleaning blade and the photosensitive drum when the photosensitive drum rotates in the reverse direction. There is an image forming apparatus that has a function of supplying (see Patent Document 2).

JP 2002-258713 A JP 2010-134359 A

  An object of the present invention is to suppress the turning-up of the contact member provided in the developing unit due to the reverse rotation of the image carrier.

According to a first aspect of the present invention, an image holding body that rotates in a first rotation direction, a charging unit that charges the image holding body, and the charged image holding body are connected to the first charging unit more than the charging unit. An exposure unit that exposes on the downstream side in the rotation direction to form an electrostatic latent image; a developer container that has an opening formed in a portion facing the image carrier and contains a developer containing toner; and A developer supply member that is rotatably provided at a location facing the opening and supplies the developer in the developer container to a portion facing the image carrier, and the first rotation than the developer supply member A contact member that is attached to the developer container at one end on the upstream side in the direction and that contacts the image carrier in the direction along the first rotation direction at the other end and suppresses leakage of the developer in the developer container And formed on the image carrier. The electrostatic latent image is obtained by developing the electrostatic latent image formed on the image holding member with a developing unit that develops the electrostatic latent image with the toner downstream of the exposure unit in the first rotation direction. A transfer unit that transfers a toner image to a transfer material downstream of the developing unit in the first rotation direction; and a downstream side of the transfer unit in the first rotation direction and the exposure unit. A plate-like cleaning member that contacts the image carrier on the upstream side in the first rotation direction and cleans deposits attached to the image carrier, and the rotation of the image carrier is stopped. After transferring toner from the developer supply member to the image carrier, the image carrier is rotated in a second rotation direction opposite to the first rotation direction, thereby transferring to the image carrier. The toner that has reached the opposite portion between the image carrier and the contact member So, the charging unit includes a contact charging member in contact with the image carrier, the rotation amount in the second rotational direction of the image carrier, the toner that has metastasized to the image carrier and a corresponding image carrier An image forming apparatus having a size that reaches a portion facing the contact member and does not reach a portion facing the image holding member and the contact charging member .

According to a second aspect of the present invention, when toner is transferred from the developer supply member to the image carrier in a state where the rotation of the image carrier is stopped, the developer supply member and the image carrier are The image forming apparatus according to claim 1, wherein a potential difference at which toner is transferred from the developer supply member to the image carrier is formed therebetween.
Third aspect of the present invention, the potential difference, an image according to claim 2, wherein the image forming operation is smaller than the other potential difference is formed between the image carrier and the developer supplying member Forming equipment.
According to a fourth aspect of the present invention, when the toner is transferred from the developer supply member to the image carrier in a state where the rotation of the image carrier is stopped, the rotation of the developer supply member is stopped. it is an image forming apparatus according to claim 2 or 3, wherein the.

According to a fifth aspect of the present invention, an image carrier that rotates in the first rotation direction, a charging unit that charges the image carrier, and the charged image carrier are connected to the first unit more than the first charging unit. An exposure unit that exposes on the downstream side in the rotation direction to form an electrostatic latent image; a developer container that has an opening formed in a portion facing the image carrier and contains a developer containing toner; and A developer supply member that is rotatably provided at a location facing the opening and supplies the developer in the developer container to a portion facing the image carrier, and the first rotation than the developer supply member A contact member that is attached to the developer container at one end on the upstream side in the direction and that contacts the image carrier in the direction along the first rotation direction at the other end and suppresses leakage of the developer in the developer container And formed on the image carrier. The electrostatic latent image is obtained by developing the electrostatic latent image formed on the image holding member with a developing unit that develops the electrostatic latent image with the toner downstream of the exposure unit in the first rotation direction. A transfer unit that transfers a toner image to a transfer material downstream of the developing unit in the first rotation direction; and a downstream side of the transfer unit in the first rotation direction and the exposure unit. A plate-shaped cleaning member that contacts the image carrier and cleans deposits attached to the image carrier on the upstream side in the first rotational direction, and rotates the image carrier in the first rotational direction. Image forming operation in which the toner image formed on the image carrier by the charging unit, the exposure unit, the developing unit, and the transfer unit is transferred to the transfer material, and the image carrier is cleaned by the cleaning member. Stop the rotation of the image carrier and stop the rotation. The toner is transferred from the developing unit to the image holding member, and then the end of the cleaning member is rotated by rotating the image holding member in a second rotation direction opposite to the first rotation direction. An image forming apparatus that performs a supply operation of removing the foreign matter adhering to the portion and supplying the toner transferred to the image holding member to a facing portion between the image holding member and the contact member.

According to a sixth aspect of the present invention, the charging unit includes a contact charging member that comes into contact with an outer peripheral surface of the image carrier, and in the supply operation, the rotation amount of the image carrier in the second rotation direction is: The size of the toner transferred to the image holding member reaches a facing portion between the image holding member and the contact member and does not reach a facing portion between the image holding member and the contact charging member. The image forming apparatus according to claim 5 .
According to a seventh aspect of the present invention, when the image carrier is rotated in the first rotation direction, the developer supply member is rotated in one rotation direction, and the image carrier is moved in the second rotation direction. When rotating, the developer supply member is rotated in the other rotation direction opposite to the one, and the rotation of the developer supply member is stopped when the rotation of the image carrier is stopped. the image forming apparatus according to claim 5 or 6, wherein further comprising a drive unit.

According to the first aspect of the present invention , the contact charging member provided in the developing unit can be prevented from being turned up due to the reverse rotation of the image holding member and the contact charging member as compared with the case where the present configuration is not provided. Toner adhesion to the toner can be suppressed .
According to the second aspect of the invention, as compared with the case not having this constitution, it is possible to transfer the toner more easily.
According to the third aspect of the present invention, the amount of toner transferred to the image carrier can be reduced compared to the case where the toner is transferred with the same potential difference as other potential differences.
According to the fourth aspect of the present invention, the amount of toner transferred to the image carrier can be reduced as compared with the case where the toner is transferred while rotating the developer supply member.
According to the fifth aspect of the present invention, it is possible to suppress the turning-up of the contact member provided in the developing unit due to the reverse rotation of the image carrier.
According to the sixth aspect of the present invention, the adhesion of toner to the contact charging member can be suppressed as compared with the case where this configuration is not provided.
According to the seventh aspect of the present invention, the drive structure of the image carrier and the developer supply member can be further simplified as compared with the case where the present structure is not provided.

1 is a diagram showing a schematic configuration of a copying machine according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating an example of a configuration of an image forming unit including a process cartridge. It is the figure which expanded the principal part of the image formation part. 3 is a diagram illustrating an example of a configuration of a control system of an image forming unit according to Embodiment 1. FIG. 6 is a timing chart for explaining an example of the operation of the image forming unit before and after the end of the image forming operation in the first embodiment. (A) is a figure which shows an example of the relationship between the main scanning direction position on a photoconductor drum in an image formation period, and a photoconductor potential, (b) is on a photoconductor drum in a stop period in a standby preparation period. FIG. 6 is a diagram illustrating an example of a relationship between a main scanning direction position and a photoreceptor potential in FIG. 6 is a diagram illustrating an example of a configuration of a control system of an image forming unit in Embodiment 2. FIG. 10 is a timing chart for explaining an example of the operation of the image forming unit before and after the end of the image forming operation in the second embodiment.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
<Embodiment 1>
FIG. 1 is a diagram showing a schematic configuration of a copying machine 1 to which the present embodiment is applied. The copying machine 1 includes an image forming apparatus 2 that forms an image on a sheet P as an example of a transfer material, and an image reading apparatus 3 that is disposed above the image forming apparatus 2 and reads an image formed on a document (not shown). And. Further, the image forming apparatus 2 includes an image forming unit 10 that forms an image and transfers the image onto the paper P, a fixing unit 20 that fixes the image transferred onto the paper P, and a paper P with respect to the image forming unit 10. And a paper supply unit 30 for supplying the paper.

  The image forming unit 10 includes a photosensitive drum 11 that is rotatably provided, a charging device 12 that charges the photosensitive drum 11, an exposure device 13 that exposes the photosensitive drum 11 charged by the charging device 12, and a charging device. A developing device 14 for developing the electrostatic latent image formed on the photosensitive drum 11 by the device 12 and the exposure device 13 with toner, and an image (toner image) developed on the photosensitive drum 11 by the developing device 14 on the paper P A transfer device 15 for transferring and a cleaning device 16 for cleaning foreign matter adhering to the photosensitive drum 11 after the transfer by the transfer device 15 are provided. In the present embodiment, among the elements constituting the image forming unit 10, the photosensitive drum 11, the charging device 12, the developing device 14, and the cleaning device 16 are integrated, and can be attached to and detached from the image forming device 2. Process cartridge 100. Further, the process cartridge 100 is configured by an EEPROM (Electrically Erasable and Programmable ROM) or the like, and stores information on the use status of the process cartridge 100 such as information indicating the type of the process cartridge 100 and the rotational speed of the photosensitive drum 11. A memory 18 is further provided. On the other hand, the read / write device 70 is attached to the image forming apparatus 2, and when the process cartridge 100 is attached to the image forming apparatus 2, the read / write device 70 sends information to the memory 18. Writing and reading of information from the memory 18 are performed.

  The fixing unit 20 includes a pair of rotating members arranged in contact with each other, and heats and presses the paper P on which the image is transferred through the pair of rotating members, thereby fixing the image on the paper P. To do.

  The paper supply unit 30 includes, for example, three paper supply units, that is, a first paper supply unit 31 in order to supply a plurality of types of paper P having different sizes, different orientations, or different paper qualities to the image forming unit 10. The second paper feed unit 32 and the third paper feed unit 33 are provided. The first paper feed unit 31 to the third paper feed unit 33 are arranged so as to overlap in the vertical direction of the image forming apparatus 2, with the first paper feed unit 31 on the upper side and the third paper feed unit 33 on the lower side. The second paper feed unit 32 is located in the middle stage.

  The first paper feed unit 31 to the third paper feed unit 33 have a common configuration. That is, each of the first paper feed unit 31 to the third paper feed unit 33 includes a paper storage unit 41 that has an opening in the top and stores the paper P therein, and a plurality of papers stored in the paper storage unit 41. A feeding roll 42 that feeds the paper P positioned at the top of the P, and a mechanism 43 that rolls the paper P fed by the feeding roll 42 one by one are provided.

  Further, the paper supply unit 30 is provided with a conveyance path R for conveying the paper P supplied from the first paper supply unit 31 to the third paper supply unit 33 from below to above the image forming apparatus 2. It has been. The conveyance path R is configured to pass through the image forming unit 10 and the fixing unit 20. Then, on the transport path R, a transport roll 44 that transports the paper P supplied from the third paper feed unit 33, a transport that transports the paper P supplied from the second paper feed unit 32 and the third paper feed unit 33. Roll 45, transports paper P supplied from first paper feed unit 31 to third paper feed unit 33, and passes through registration roll 46 and fixing unit 20 for adjusting the supply timing of paper P to image forming unit 10 A discharge roll 47 is provided for conveying the discharged paper P to the outside of the apparatus. A paper stacking unit 2 a for stacking fixed paper P discharged via the discharge roll 47 is provided on the upper portion of the image forming apparatus 2.

  In addition, the image forming apparatus 2 includes a receiving unit 400 that receives image data from the image reading device 3, a personal computer (PC) (not shown), a control unit 500 that controls the operation of the image forming apparatus 2, and the received image data. And an image processing unit 600 that performs image processing and outputs the processed image to the exposure apparatus 13. Further, the image forming apparatus 2 includes a user interface (UI) 700 that includes a display panel, various buttons, and the like and receives an instruction from the user. The control unit 500 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk Drive) (all not shown). The CPU executes various processing programs. The ROM stores various programs, various tables, parameters, and the like. The RAM is used as a work area when the CPU executes various programs.

  FIG. 2 is a cross-sectional view illustrating an example of the configuration of the image forming unit 10 including the process cartridge 100 described above. In FIG. 2, the components of the process cartridge 100 are indicated by solid lines, and the exposure device 13 and the transfer device 15 are indicated by two-dot chain lines. FIG. 3 is an enlarged view of a main part of the image forming unit 10 shown in FIG.

  The photosensitive drum 11 as an example of the image carrier is formed by forming a photosensitive layer on the outer peripheral surface of a thin metal cylindrical drum made of metal, and the photosensitive layer is made of a material having a negative charging polarity. Note that the cylindrical drum constituting the photosensitive drum 11 is grounded. Further, the photosensitive drum 11 of the present embodiment is configured to rotate in the direction of arrow A (clockwise in the figure) in the image forming operation for forming an image on the paper P. Further, the photosensitive drum 11 of the present embodiment can be rotated in the direction of arrow B (counterclockwise direction in the figure) which is opposite to the direction indicated by arrow A. The photosensitive drum 11 is rotationally driven by a common drive motor 61 (see FIG. 4) described later. In the present embodiment, the arrow A direction corresponds to the first rotation direction, and the arrow B direction corresponds to the second rotation direction.

  Further, in the image forming unit 10 of the present embodiment, a charging device 12, an exposure device 13, a developing device 14, a transfer device 15, and a cleaning device 16 are disposed around the photosensitive drum 11 along the direction of arrow A. ing.

  The charging device 12 as an example of a charging unit is configured by, for example, a cylindrical charging roll, and the surface of the charging drum 12 extends along the main scanning direction that intersects the rotation direction of the photosensitive drum 11. It arrange | positions so that an outer peripheral surface may be contacted. In the following description, a contact portion between the photosensitive drum 11 and the charging roll is referred to as a charging position Pch. The charging roll is configured to receive a driving force from the outer peripheral surface of the photosensitive drum 11 and rotate. A charging roll as an example of a contact charging member is made of, for example, a rubber material, and a negative charging bias is applied by a charging power source 62 (see FIG. 4) described later.

  An exposure apparatus 13 as an example of an exposure unit emits a beam Bm corresponding to image data from a light source (not shown) driven by a light source driving unit 63 (see FIG. 4) described later, for example, to the outer periphery of the photosensitive drum 11. Emits to the surface. Then, the exposure device 13 of the present embodiment forms an electrostatic latent image by irradiating light on the position where the toner image is to be formed on the outer peripheral surface of the photosensitive drum 11 charged by the charging device 12. ing. In the following description, an irradiation site of the beam Bm on the photosensitive drum 11 by the exposure device 13 is referred to as an exposure position Pex.

  The developing device 14 as an example of the developing unit is an example of a developing container in which an opening facing the outer peripheral surface of the photosensitive drum 11 is formed and a developer (not shown) containing toner and a carrier is accommodated therein. Development housing 141, and a development roll 142 that is rotatably disposed at a location facing the opening of the development housing 141. Here, the developing roll 142 is disposed in non-contact with the photosensitive drum 11. In the following description, a facing portion between the photosensitive drum 11 and the developing roll 142 is referred to as a developing position Pde. Further, in the developing housing 141, the first stirring / conveying member 143 and the second stirring / conveying member disposed along the axial direction of the photosensitive drum 11 on the lower back side of the developing roller 142 as viewed from the photosensitive drum 11. A member 144 is provided. In addition, a partition wall that partitions the first stirring and conveying member 143 and the second stirring and conveying member 144 is provided between the first stirring and conveying member 143 and the second stirring and conveying member 144. This partition wall is formed integrally with the developing housing 141. Note that no partition walls are provided on both axial ends of the first stirring and conveying member 143 and the second stirring and conveying member 144, and the inside of the developing housing 141 is formed by the first stirring and conveying member 143 and the second stirring and conveying member 144. The developer is circulated and conveyed. Further, a layer thickness regulating member 145 that is attached to the developing housing 141 and regulates the layer thickness of the developer that adheres to the developing roll 142 is provided at an upper right side of the developing roll 142 in the drawing.

  In the developing device 14 of the present embodiment, a so-called two-component developer including a black colored toner and a magnetic carrier is used as the developer. In this developer, the carrier has a positive charging polarity, and the toner has a negative charging polarity.

  A developing roll 142 as an example of a developer supply member is disposed rotatably inside a hollow developing sleeve 142a that is rotatably disposed, and a plurality of magnetic poles (inside the developing sleeve 142a). (Not shown) and a magnet roll 142b. The developing sleeve 142a rotates in the direction of arrow C (counterclockwise direction in the figure) in the image forming operation for forming an image on the paper P. Further, the developing sleeve 142a of the present embodiment can be rotated in the direction of arrow D which is opposite to the direction of arrow C. The developing sleeve 142a is rotationally driven by a common drive motor 61 (see FIG. 4) described later. Further, the developing sleeve 142a is made of, for example, a metal such as SUS, and a developing bias is applied by a developing power source 64 (see FIG. 4) described later. In the present embodiment, the arrow C direction corresponds to one rotational direction, and the arrow D direction corresponds to the other rotational direction.

  In addition, the developing device 14 includes a first seal 146 attached to the developing housing 141 on the upstream side in the direction of the arrow A from the developing position Pde, and a developing position Pde, in a portion facing the opening provided in the developing housing 141. And a second seal 147 attached to the developing housing 141 on the downstream side in the direction of arrow A. The first seal 146 and the second seal 147 are made of, for example, PET (polyethylene terephthalate) formed into a film shape, and each has a rectangular shape extending along the main scanning direction. .

  A first seal 146 as an example of a contact member has one end side in the longitudinal direction fixed to the developing housing 141. The first seal 146 is attached to the developing housing 141 such that the direction from one end side to the other end side in the longitudinal direction is along the arrow A direction. At least a part of the first seal 146 comes into contact with the outer peripheral surface of the photosensitive drum 11. In the following description, a contact portion between the photosensitive drum 11 and the first seal 146 is referred to as a seal position Pse. On the other hand, the second seal 147 is also fixed to the developing housing 141 at one end in the longitudinal direction. The second seal 147 is attached to the developing housing 141 such that the direction from one end side to the other end side in the longitudinal direction is opposite to the arrow C direction. At least a part of the second seal 147 comes into contact with the outer peripheral surface of the developing roll 142 (more specifically, the developing sleeve 142a).

  The transfer device 15 as an example of the transfer unit is configured by, for example, a cylindrical transfer roll, and the surface thereof is arranged so as to be in contact with the outer peripheral surface of the photosensitive drum 11 along the main scanning direction. Yes. In the following description, a facing portion between the photosensitive drum 11 and the transfer roll is referred to as a transfer position Ptr. The transport path R is provided so as to pass the transfer position Ptr. This transfer roll is also configured to rotate by receiving a driving force directly from the outer peripheral surface of the photosensitive drum 11 or via the paper P. The transfer roll is made of, for example, a rubber material, and a positive transfer bias is applied by a transfer power supply 65 (see FIG. 4) described later.

  The cleaning device 16 includes a cleaner housing 161 in which an opening facing the outer peripheral surface of the photosensitive drum 11 is formed and a space is formed therein, and a cleaning blade 162 disposed at a location facing the opening of the cleaner housing 161. And. The cleaning blade 162 as an example of the cleaning member is configured by, for example, polyurethane rubber or the like molded into a rectangular shape and a plate shape. One end of the cleaning blade 162 in the longitudinal direction is fixed to the cleaner housing 161. The cleaning blade 162 is attached to the cleaner housing 161 such that the direction from one end side to the other end side in the longitudinal direction is opposite to the arrow A direction. The other end in the longitudinal direction of the cleaning blade 162 is in contact with the outer peripheral surface of the photosensitive drum 11. In the following description, a contact portion between the photosensitive drum 11 and the cleaning blade 162 is referred to as a cleaning position Pcl.

  The cleaning device 16 further includes a transport member 163 that is provided inside the cleaner housing 161 and transports foreign matter scraped off from the outer peripheral surface of the photosensitive drum 11 by the cleaning blade 162 toward a collection container (not shown). ing. The foreign matter scraped off by the cleaning blade 162 includes toner (residual toner) remaining on the outer peripheral surface of the photosensitive drum 11 without being transferred to the paper P in the transfer by the transfer device 15, and from the paper P to the photosensitive drum. 11 and the like which have been transferred to the outer peripheral surface.

  The cleaning device 16 further includes a cleaner seal 164 attached to the cleaner housing 161 on the upstream side in the arrow A direction from the cleaning position Pcl in the portion facing the opening provided in the cleaner housing 161. The cleaner seal 164 is made of, for example, PET (polyethylene terephthalate) or the like formed into a film shape, and has a rectangular shape extending along the main scanning direction. One end of the cleaner seal 164 in the longitudinal direction is fixed to the cleaner housing 161. The cleaner seal 164 is attached to the cleaner housing 161 such that the direction from one end side to the other end side in the longitudinal direction is along the arrow A direction. At least a part of the cleaner seal 164 is in contact with the outer peripheral surface of the photosensitive drum 11.

  In the present embodiment, the distance between the charging device 12 and the developing device 14 in the process cartridge 100 is narrowed in order to reduce the size of the process cartridge 100 and thus the image forming apparatus 2. For this reason, the beam Bm emitted from the exposure device 13 passes through a narrow space between the charging device 12 and the developing device 14 and is irradiated onto the photosensitive drum 11.

FIG. 4 is a diagram showing an example of the configuration of the control system of the image forming unit 10 in the present embodiment.
The control unit 500 charges a charging roller provided in the common drive motor 61 and the charging device 12 as an example of a common rotation driving unit that rotationally drives the developing sleeve 142 a provided in the photosensitive drum 11 and the developing device 14 together. A charging power source 62 that supplies a bias, a light source driving unit 63 that drives a light source provided in the exposure device 13, a developing power source 64 that supplies a developing bias to a developing sleeve 142 a provided in the developing device 14, and a transfer device 15. A control signal is output to each transfer power supply 65 that supplies a transfer bias to the transfer rolls. Although not shown because the control system of the image forming unit 10 is shown here, the control unit 500 sends a control signal to each unit constituting the fixing unit 20 and the paper supply unit 30 in addition to this. Output.

  In the present embodiment, as described above, the photosensitive drum 11 and the developing sleeve 142a are rotationally driven by the common drive motor 61 in a lump. Thus, when the photosensitive drum 11 rotates in the direction of arrow A (see FIG. 2) as the common drive motor 61 rotates forward, the developing sleeve 142a rotates in the direction of arrow C (see FIG. 2). Further, when the photosensitive drum 11 rotates in the arrow B direction (see FIG. 2) with the reverse rotation of the common drive motor 61, the developing sleeve 142a rotates in the arrow D direction (see FIG. 2). Furthermore, when the common drive motor 61 stops rotating, both the photosensitive drum 11 and the developing sleeve 142a stop rotating. Accordingly, when the photosensitive drum 11 rotates in the arrow A direction and the developing sleeve 142a rotates in the arrow C direction, and the photosensitive drum 11 rotates in the arrow B direction and the developing sleeve 142a rotates in the arrow D direction. In each case, the photosensitive drum 11 and the developing sleeve 142a rotate in the same direction at the developing positions where they face each other. Further, when the photosensitive drum 11 rotates in the arrow A direction and the developing sleeve 142a rotates in the arrow C direction, and the photosensitive drum 11 rotates in the arrow B direction and the developing sleeve 142a rotates in the arrow D direction. In each case, the peripheral speed of the developing sleeve 142a is set to be higher (for example, twice) than the peripheral speed of the photosensitive drum 11.

  In the following description, rotation of the photosensitive drum 11 in the arrow A direction is referred to as normal rotation, and rotation in the arrow B direction is referred to as reverse rotation. The rotation of the developing sleeve 142a in the direction of arrow C is referred to as normal rotation, and the rotation in the direction of arrow D is referred to as reverse rotation.

Now, an outline of an image forming operation executed by the image forming apparatus 2 shown in FIG. 1 will be described.
When the receiving unit 400 receives image data output from a personal computer (not shown) or the image reading device 3, the control unit 500 controls the image forming unit 10, the fixing unit 20, and the paper supply unit 30 that form the image forming apparatus 2. An image forming operation is executed by outputting a control signal. Note that the image data received by the receiving unit 400 is output to the image processing unit 600, subjected to image processing in the image processing unit 600, and then output to the exposure apparatus 13.

  When executing the image forming operation, the image forming unit 10 charges the photosensitive drum 11 rotating (forward rotation) in the direction of arrow A using the charging device 12 and the exposure and developing device 14 using the exposure device 13. The development used is sequentially performed. As a result, a toner image, that is, an image is formed on the photosensitive drum 11.

  In addition, the paper supply unit 30 performs an operation of supplying the paper P from any one of the first paper supply unit 31 to the third paper supply unit 33 that stores the paper P that is an object of image formation. The supplied paper P is transported to a position where the leading end in the transport direction reaches the registration roll 46 and then temporarily stops. Thereafter, the registration roll 46 starts to rotate, and the paper P reaches the transfer position in accordance with the time when the image on the photoconductive drum 11 that normally rotates reaches the transfer position.

Subsequently, in the image forming unit 10, the transfer device 15 transfers the image on the photosensitive drum 11 to the conveyed paper P.
The paper P onto which the image has been transferred undergoes a fixing process in the fixing unit 20 and is discharged to the paper stacking unit 2a.

Next, the operation of the image forming unit 10 in the above-described image forming operation will be described with reference to FIGS.
In the image forming unit 10, when the common drive motor 61 starts normal rotation, the photosensitive drum 11 starts to rotate in the direction of arrow A (forward rotation) and is provided on the developing roll 142 of the developing device 14. The developing sleeve 142a starts to rotate in the direction of arrow C (forward rotation). In the developing device 14, the first stirring / conveying member 143 and the second stirring / conveying member 144 also start rotating together with the developing sleeve 142a. Further, as the photosensitive drum 11 starts normal rotation, the charging roll provided in the charging device 12 and the transfer roll provided in the transfer device 15 also start rotating. Further, supply of the charging bias from the charging power source 62 to the charging device 12 (charging roll) is started. Furthermore, the light source driving unit 63 instructs the exposure apparatus 13 to output the beam Bm according to the image data. Further, the supply of the developing bias from the developing power source 64 to the developing sleeve 142a of the developing device 14 is started. Further, supply of a transfer bias from the transfer power supply 65 to the transfer device 15 (transfer roll) is started.

The image forming unit 10 forms an image according to the following procedure.
First, the photosensitive layer of the photosensitive drum 11 that has passed through the charging position Pch in contact with the charging roll of the charging device 12 is charged to the charging potential VH over the entire surface. Note that the charging potential VH in this example is about −700 V, for example.
Next, in the photosensitive layer of the photosensitive drum 11 that has passed through the exposure position Pex irradiated with the beam Bm from the exposure device 13, a region (background region) that is not an irradiation target is maintained at the charging potential VH. A region (image region) that is an irradiation target becomes an exposure potential VL. In this manner, an electrostatic latent image including the background area of the charging potential VH and the image area of the exposure potential VL is formed on the photosensitive layer of the photosensitive drum 11 that has passed the exposure position Pex. Note that the exposure potential VL in this example is, for example, about −100V.

  Subsequently, the photosensitive layer of the photosensitive drum 11 on which the electrostatic latent image is formed passes through the seal position Pse facing the first seal 146 provided in the developing device 14 and then the developing provided in the developing device 14. It reaches the developing position Pde facing the roll 142 (more specifically, the developing sleeve 142a).

  In the developing device 14, the first agitating / conveying member 143 and the second agitating / conveying member 144 rotate with the start of the image forming operation, and the developer is agitated and conveyed in the developing housing 141. By this agitation and conveyance, the toner and the carrier constituting the developer are rubbed with each other, and the toner is charged with negative polarity and the carrier is charged with positive polarity. As a result, in the developer that is stirred and conveyed, the toner is electrostatically attracted to the carrier. When the developer to be agitated and conveyed is conveyed to a portion facing the developing roll 142, a part of the carrier is caused by the magnetic force acting between the magnetic pole provided on the magnet roll 142b and the carrier contained in the developer. Transition to the developing roll 142 side. At this time, since the toner is electrostatically adsorbed on the carrier transferred to the developing roll 142 side, the developer is transferred to the developing roll 142 side as a result, and the development with the developer is performed on the outer peripheral surface of the developing sleeve 142a. An agent layer is formed. The developer layer formed on the developing sleeve 142a is regulated to a predetermined thickness when passing through a portion facing the layer thickness regulating member 145 as the developing sleeve 142a rotates forward. It is carried to the opening of the developing housing 141 facing the body drum 11. The developer regulated by the layer thickness regulating member 145 is returned to the first stirring and conveying member 143 side by gravity.

  In the developing device 14, the first developing bias VB1 is applied as the developing bias VB from the developing power source 64 to the developing sleeve 142a with the start of the image forming operation. The first developing bias VB1 is set to a magnitude (for example, −400 V) between the charging potential VH and the exposure potential VL. By performing such setting, at the development position Pde, the toner is electrostatically transferred from the developer layer on the developing sleeve 142a to the image area on the photosensitive drum 11 (area where the exposure potential is VL). Then, the electrostatic latent image is developed to make a visible image. That is, in this example, the toner image is developed by the reversal development method. The behavior of the toner at this time will be described later. In this example, since the peripheral speed of the developing sleeve 142a is set higher than the peripheral speed of the photosensitive drum 11, it is easy to secure a toner amount necessary for development at the developing position Pde. Thereafter, the developer layer on the developing sleeve 142a that has passed the developing position Pde passes through the portion facing the second seal 147 as the developing sleeve 142a rotates forward, and is returned to the developing housing 141. The developer layer on the developing sleeve 142a returned to the developing housing 141 is separated from the developing roll 142 by the repulsive magnetic field formed by the magnetic poles provided on the magnet roll 142b and falls into the developing housing 141. Then, the first agitating / conveying member 143 and the second agitating / conveying member 144 are again agitated and conveyed to wait for the next development.

Next, the photosensitive layer of the photosensitive drum 11 on which the image is formed by passing through the development position Pde reaches the transfer position Ptr facing the transfer roll provided in the transfer device 15.
In the transfer device 15, a positive transfer bias is applied to the transfer roll from the transfer power supply 65 with the start of the image forming operation. By performing such setting, the toner (negatively charged) constituting the image formed on the photosensitive drum 11 is transferred and attached to the paper P passing through the transfer position Ptr at the transfer position Ptr.

  Thereafter, the photosensitive layer of the photosensitive drum 11 that has completed the transfer of the toner by passing through the transfer position Ptr passes through a portion facing the cleaner seal 164 provided in the cleaning device 16 and then provided in the cleaning device 16. The cleaning position Pcl facing the cleaning blade 162 is reached.

  To the photosensitive layer of the photosensitive drum 11 that has passed the transfer position Ptr, toner that has not been transferred to the paper P (residual toner), paper powder that has been transferred from the paper P at the transfer position Ptr, and the like adhere to the photosensitive layer. . The cleaning blade 162 scrapes off such foreign matter at the cleaning position Pcl and collects it in the cleaner housing 161. And the foreign material collect | recovered in the cleaner housing 161 is conveyed toward the collection | recovery container (not shown) provided outside by the conveyance member 163. FIG.

  Then, the photosensitive layer of the photosensitive drum 11 that has been cleaned of foreign matters by passing through the cleaning position Pcl reaches the charging position Pch again, and thereafter, the image is formed by repeating the above-described procedure. Will go.

  In the image forming operation, in the developing device 14, the toner may float away from the developer layer on the developing sleeve 142a that has passed through the portion facing the layer thickness regulating member 145. In the present embodiment, by providing the developing device 14 with the first seal 146, the toner floating in the upstream direction in the arrow A direction from the developing position Pde in the developing device 14 is suppressed from leaking to the charging device 12 side. ing.

Next, processing performed by the image forming unit 10 after the end of the image forming operation will be described.
FIG. 5 is a timing chart for explaining an example of the operation of the image forming unit 10 before and after the end of the image forming operation in the present embodiment. In the initial state in FIG. 5, the above-described image forming operation is executed. Therefore, in the initial state in FIG. 5, the photosensitive drum 11 and the developing roll 142 (developing sleeve 142 a) are normally rotated by the driving force received from the common driving motor 61. In the initial state in FIG. 5, the charging bias is supplied to the charging device 12 (charging roll), the exposure signal is supplied to the exposure device 13, the developing bias VB is supplied to the developing roll 142 (developing sleeve 142a) of the developing device 14, The transfer bias is supplied to the transfer device 15 (transfer roll). Note that the magnitude of the developing bias VB at this time is set to the first developing bias VB1.

  When the exposure corresponding to the last image in the image forming operation is completed at time t0, the supply of the exposure signal is stopped. At time t1 after the last image transfer is completed, the supply of the charging bias, the supply of the development bias VB (first development bias VB1), and the supply of the transfer bias are stopped. Even after the time t1 has elapsed, since the common drive motor 61 continues to rotate normally, the photosensitive drum 11 and the developing sleeve 142a continue to rotate normally. Accordingly, even after time t1, the developer layer formed on the developing sleeve 142a passes through the developing position Pde. At this time, the photosensitive drum 11 passing through the developing position Pde is charged and exposed. In addition, since the supply of the developing bias VB to the developing sleeve 142a is also stopped, toner transfer from the developing sleeve 142a to the photosensitive drum 11 hardly occurs.

  Next, as the common drive motor 61 stops normal rotation at time t2, the photosensitive drum 11 and the developing roll 142 stop normal rotation. At this time, the developer layer is still formed on the surface of the developing sleeve 142a at the developing position Pde.

  Subsequently, at time t3, the development bias VB is set to the second development bias VB2. The second developing bias VB2 is set to a magnitude (for example, -200 V) between the residual potential VR (for example, -50 V) of the photosensitive layer of the photosensitive drum 11 and the first developing bias VB1 (for example, -400 V). ing. Here, the residual potential VR is generated by the charge remaining in the photosensitive layer due to fatigue of the photosensitive layer after the charging of the photosensitive drum 11 is completed. By performing such setting, toner is electrostatically transferred and attached from the developer layer on the developing sleeve 142a to the photosensitive drum 11 at the developing position Pde, and the photosensitive drum 11 at the developing position Pde is applied to the photosensitive drum 11. A belt-like toner adhesion region is formed. The behavior of the toner at this time will be described later. Thereafter, at time t4, the supply of the developing bias VB (second developing bias VB2) is stopped.

  Then, as the common drive motor 61 starts reverse rotation at time t5, the photosensitive drum 11 and the developing roll 142 respectively start reverse rotation. Thereafter, at time t6, as the common drive motor 61 stops the reverse rotation, the photosensitive drum 11 and the developing roll 142 stop the reverse rotation, respectively.

  Hereinafter, the time until time t1 is referred to as an image forming period Ta, the time from time t1 to time t6 is referred to as a standby preparation period Tb, and the time after time t6 is referred to as a standby period Tc. In the standby preparation period Tb, the period from time t1 to time t2 is called a normal rotation period Tx, the period from time t2 to time t5 is called a stop period Ty, and the period from time t5 to time t6 is called a reverse rotation period Tz. Further, in the stop period Ty, the period from time t3 to time t4 is referred to as a toner supply period Tw.

  In accordance with the reverse rotation of the photosensitive drum 11 during the reversal period Tz, in the cleaning device 16, the foreign matter adhering to the tip side of the cleaning blade 162 or the foreign matter sandwiched between the cleaning blade 162 and the photosensitive drum 11 is cleaned. It becomes easier to move away from the blade 162.

  Further, the moving distance of the outer peripheral surface of the photosensitive drum 11 during the reverse rotation period Tz is a belt-like shape that is transferred and attached to the photosensitive drum 11 located at the development position Pde during the stop period Ty (more specifically, the toner supply period Tw). The toner adhesion area is set to a size that reaches the seal position Pse and does not reach the charging position Pch. As a result, the toner adhering to the photoconductive drum 11 is sandwiched between the photoconductive drum 11 and the first seal 146 at the seal position Pse, so that it functions as a lubricant, and both of them become slippery. Therefore, the first seal 146 is not easily turned over due to the reverse rotation of the photosensitive drum 11. In particular, in the present embodiment, since the attachment position of the first seal 146 and the exposure position Pex are close to each other, the first seal 146 is turned over when the photosensitive drum 11 is reversed. There is a concern that the exposure position Pex is blocked by the seal 146 (a state indicated by a two-dot chain line in FIG. 3). Further, by preventing the belt-like toner adhesion region formed on the photosensitive drum 11 from reaching the charging position Pch, the charging roll is hardly contaminated with toner.

Next, the behavior of the toner at the development position Pde in the image forming period Ta and the standby preparation period Tb (more specifically, the toner supply period Tw) will be described. In the present embodiment, an image forming operation is performed during the image forming period Ta, and a supplying operation is performed during the standby preparation period Tb.
FIG. 6A shows an example of the relationship between the position of the photosensitive drum 11 in the main scanning direction at the development position Pde and the potential of the photosensitive drum 11 (referred to as the photosensitive member potential) in the image forming period Ta. Yes. Here, as described above, it is assumed that the charging potential VH of the photosensitive drum 11 is −700 V, the exposure potential VL is −100 V, for example, and the first developing bias VB1 supplied to the developing sleeve 142a is −400 V, for example. In this case, the exposure potential VL is relatively positive with respect to the first developing bias VB1, and the charging potential VH is relatively negative with respect to the first developing bias VB1. Therefore, the negative polarity toner held on the developing sleeve 142a is easily transferred to the image area of the exposure potential VL that is relatively positive, while the area of the charging potential VH that is relatively negative is in the background area. It becomes difficult to transfer. In this example, the potential difference (referred to as first development potential difference VD1) between the exposure potential VL and the development bias VB (first development bias VB1) is 300V.

  FIG. 6B shows an example of the relationship between the position of the photosensitive drum 11 in the main scanning direction at the developing position Pde and the photosensitive member potential in the toner supply period Tw in the stop period Ty of the standby preparation period Tb. ing. Here, as described above, it is assumed that the residual potential VR in the photosensitive drum 11 is −50 V, for example, and the second developing bias VB2 supplied to the developing sleeve 142a is −200 V, for example. In this case, the residual potential VR is relatively positive with respect to the second developing bias VB2. Accordingly, the negative toner held on the developing sleeve 142a is likely to be transferred to the photosensitive drum 11 side located in the relatively positive residual potential VR region, that is, the developing position Pde. At this time, since the photosensitive member potential at the development position Pde is the residual potential VR along the main scanning direction, the outer peripheral surface of the photosensitive drum 11 located at the development position Pde is along the main scanning direction. The toner adheres in a band shape. However, the potential difference (referred to as the second development potential difference VD2) between the residual potential VR and the development bias VB (second development bias VB2) in this example is 150 V, which is smaller than the first development potential difference VD1 described above. The transfer amount is smaller than that during the image forming operation. In addition, since the developing sleeve 142a is rotating during the image forming period Ta, while the developing sleeve 142a is stopped during the toner supply period Tw, the amount of toner supplied to the developing position Pde is limited. Also in this respect, the toner transfer amount is smaller than that in the image forming operation.

<Embodiment 2>
The present embodiment is substantially the same as the first embodiment, but the method of supplying toner to the photosensitive drum 11 in the toner supply period Tw is different from that of the first embodiment. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

FIG. 7 is a diagram illustrating an example of a configuration of a control system of the image forming unit 10 in the present embodiment.
In the first embodiment, the photosensitive drum 11 and the developing sleeve 142a are collectively driven using the common drive motor 61. On the other hand, in the present embodiment, a first drive motor 61a that rotates the photosensitive drum 11 and a second drive motor 61b that rotates the developing sleeve 142a are provided separately, and the control unit 500 provides these. A control signal is output respectively.

  In the image forming operation, the photosensitive drum 11 and the developing sleeve 142a are driven separately, but the photosensitive drum 11 rotates normally in the direction of arrow A and the developing sleeve 142a rotates in the direction of arrow C. become.

Now, a process executed by the image forming unit 10 after the end of the image forming operation will be described.
FIG. 8 is a timing chart for explaining an example of the operation of the image forming unit 10 before and after the end of the image forming operation in the present embodiment. In the initial state in FIG. 8, the above-described image forming operation is executed. Therefore, in the initial state in FIG. 8, the photosensitive drum 11 rotates normally by the driving force received from the first drive motor 61a, and the developing roll 142 (developing sleeve 142a) rotates normally by the driving force received from the second drive motor 61b. ing. Further, in the initial state shown in FIG. 8, the charging bias is supplied to the charging device 12 (charging roll), the exposure signal is supplied to the exposure device 13, the developing bias VB is supplied to the developing roll 142 (developing sleeve 142a) of the developing device 14, The transfer bias is supplied to the transfer device 15 (transfer roll). Note that the magnitude of the developing bias VB at this time is set to the first developing bias VB1.

  When the exposure corresponding to the last image in the image forming operation is completed at time t0, the supply of the exposure signal is stopped. At time t1 after the last image transfer is completed, the supply of the charging bias, the supply of the development bias VB (first development bias VB1), and the supply of the transfer bias are stopped. Even after the time t1 has elapsed, the first drive motor 61a and the second drive motor 61b continue to rotate normally, so that the photosensitive drum 11 and the developing sleeve 142a continue to rotate normally. Accordingly, even after time t1, the developer layer formed on the developing sleeve 142a passes through the developing position Pde. At this time, the photosensitive drum 11 passing through the developing position Pde is charged and exposed. In addition, since the supply of the developing bias VB to the developing sleeve 142a is also stopped, toner transfer from the developing sleeve 142a to the photosensitive drum 11 hardly occurs.

  Subsequently, at time t3, the developing roller 142 starts normal rotation as the second drive motor 61b starts normal rotation. At this time, since the first drive motor 61a remains stopped, the photosensitive drum 11 stops rotating, and the supply of the developing bias VB also remains stopped. By performing such setting, the developer layer formed on the developing sleeve 142a moves while rubbing the outer peripheral surface of the photosensitive drum 11 at the developing position Pde, and the developer layer on the developing sleeve 142a is moved. Accordingly, a part of the toner is physically transferred and adhered to the photosensitive drum 11, and a belt-like toner adhesion region is formed on the photosensitive drum 11 at the development position Pde. Thereafter, at time t4, as the normal rotation of the second drive motor 61b stops, the developing roll 142 stops normal rotation.

  Then, as the first drive motor 61a starts reverse rotation at time t5, the photosensitive drum 11 starts reverse rotation. At this time, since the second drive motor 61b remains stopped, the developing roll 142 stops rotating. Thereafter, as the first drive motor 61a stops reverse rotation at time t6, the developing roller 142 stops reverse rotation.

  Also in the present embodiment, as the photosensitive drum 11 rotates in the reverse rotation period Tz, the cleaning device 16 has a foreign matter adhering to the front end side of the cleaning blade 162 or between the cleaning blade 162 and the photosensitive drum 11. It becomes easy for the foreign matter sandwiched to move away from the cleaning blade 162.

  Also in the present embodiment, the movement distance of the outer peripheral surface of the photosensitive drum 11 during the reverse rotation period Tz is equal to the photosensitive drum 11 positioned at the development position Pde during the stop period Ty (more specifically, the toner supply period Tw). The belt-like toner adhering region transferred and adhering to is set to a size that reaches the seal position Pse and does not reach the charging position Pch.

In the first and second embodiments, the reverse operation of the photosensitive drum 11 is executed at the end of the image forming operation. However, the present invention is not limited to this, and it is performed before the start of the image forming operation. It doesn't matter.
In this embodiment, the reverse operation of the photosensitive drum 11 is always executed at the end of the image forming operation. However, the present invention is not limited to this. For example, the rotational speed of the photosensitive drum 11 is used. Alternatively, the photosensitive drum 11 may be reversely rotated periodically.

DESCRIPTION OF SYMBOLS 2 ... Image forming apparatus, 10 ... Image forming part, 11 ... Photoconductor drum, 12 ... Charging device, 13 ... Exposure device, 14 ... Developing device, 141 ... Developing housing, 142 ... Developing roll, 142a ... Developing sleeve, 142b ... Magnet roll, 143... First stirring and conveying member, 144... Second agitating and conveying member, 145... Layer thickness regulating member, 146... First seal, 147 ... Second seal, 15 ... Transfer device, 16 ... Cleaning device, 161. Cleaner housing 162 162 Cleaning blade 163 Conveying member 164 Cleaner seal 61 Common drive motor 61a First drive motor 62 Charging power source 63 Light source drive unit 64 Development power source 65 Transfer Power supply, P ... paper, Pch ... charge position, Pex ... exposure position, Pse ... seal position, Pde ... develop position, Ptr ... transfer position, Pc ... cleaning position

Claims (7)

An image carrier that rotates in a first rotational direction;
A charging unit for charging the image carrier;
An exposure unit that exposes the charged image carrier on the downstream side of the charging unit in the first rotation direction to form an electrostatic latent image; and
A developer container in which an opening is formed at a portion facing the image carrier and a developer containing toner is accommodated therein, and the developer provided rotatably in a portion facing the opening and in the developer container A developer supply member for supplying the developer to a portion facing the image carrier, and one end side is attached to the developer container on the upstream side in the first rotation direction from the developer supply member, and the other end side is the first A contact member that is in contact with the image carrier in a direction along the rotation direction and suppresses leakage of the developer in the developer container, and the electrostatic latent image formed on the image carrier is A developing unit for developing with the toner on the downstream side in the first rotation direction from the exposure unit;
A transfer unit that transfers a toner image obtained by developing the electrostatic latent image formed on the image carrier to a transfer material downstream of the developing unit in the first rotation direction;
A plate that contacts the image carrier and cleans deposits attached to the image carrier downstream of the transfer unit in the first rotational direction and upstream of the exposure unit in the first rotational direction. In the form of a cleaning member,
After the toner is transferred from the developer supply member to the image holding member in a state where the rotation of the image holding member is stopped, the second rotation of the image holding member opposite to the first rotation direction is performed. By rotating in the direction, the toner transferred to the image carrier is made to reach the facing portion between the image carrier and the contact member ,
The charging unit includes a contact charging member that contacts the image carrier,
The amount of rotation of the image carrier in the second rotation direction is such that the toner transferred to the image carrier reaches the facing portion between the image carrier and the contact member, and the image carrier and the contact charge. An image forming apparatus having a size that does not reach a portion facing a member .   When transferring toner from the developer supply member to the image carrier in a state where the rotation of the image carrier is stopped, the developer supply member between the developer supply member and the image carrier. The image forming apparatus according to claim 1, wherein a potential difference at which toner is transferred to the image holding member is formed. 3. The image forming apparatus according to claim 2 , wherein the potential difference is smaller than other potential differences formed between the developer supply member and the image carrier in an image forming operation. 3. The rotation of the developer supply member is stopped when toner is transferred from the developer supply member to the image support in a state where the rotation of the image support is stopped. Or the image forming apparatus according to 3 . An image carrier that rotates in a first rotational direction;
A charging unit for charging the image carrier;
An exposure unit that exposes the charged image carrier on the downstream side of the charging unit in the first rotation direction to form an electrostatic latent image; and
A developer container in which an opening is formed at a portion facing the image carrier and a developer containing toner is accommodated therein, and the developer provided rotatably in a portion facing the opening and in the developer container A developer supply member for supplying the developer to a portion facing the image carrier, and one end side is attached to the developer container on the upstream side in the first rotation direction from the developer supply member, and the other end side is the first A contact member that is in contact with the image carrier in a direction along the rotation direction and suppresses leakage of the developer in the developer container, and the electrostatic latent image formed on the image carrier is A developing unit for developing with the toner on the downstream side in the first rotation direction from the exposure unit;
A transfer unit that transfers a toner image obtained by developing the electrostatic latent image formed on the image carrier to a transfer material downstream of the developing unit in the first rotation direction;
A plate that contacts the image carrier and cleans deposits attached to the image carrier downstream of the transfer unit in the first rotational direction and upstream of the exposure unit in the first rotational direction. In the form of a cleaning member,
The image carrier is rotated in the first rotation direction, the toner image formed on the image carrier by the charging unit, the exposure unit, the developing unit, and the transfer unit is transferred to the transfer material, An image forming operation for cleaning the image holding member with the cleaning member, and rotation of the image holding member is stopped, and toner is transferred from the developing unit to the image holding member whose rotation is stopped, and then the image holding member. Is rotated in a second rotational direction opposite to the first rotational direction to remove foreign matter adhering to the end of the cleaning member and to transfer the toner transferred to the image carrier to the image carrier. An image forming apparatus that performs a supply operation to supply a portion facing the contact member. The charging unit includes a contact charging member that contacts an outer peripheral surface of the image carrier,
In the supply operation, the rotation amount of the image holding member in the second rotation direction is such that the toner transferred to the image holding member reaches the facing portion between the image holding member and the contact member and the image holding member is held. The image forming apparatus according to claim 5 , wherein the image forming apparatus has a size that does not reach a facing portion between a body and the contact charging member. When the image carrier is rotated in the first rotation direction, the developer supply member is rotated in one rotation direction, and when the image carrier is rotated in the second rotation direction, the developer supply is performed. A common rotation drive unit is further provided to stop the rotation of the developer supply member when the member is rotated in the other rotation direction opposite to the one and the rotation of the image carrier is stopped. The image forming apparatus according to claim 5 or 6 .

Images