JP2018132585A - Developing device, image forming apparatus, method for controlling developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that can reduce attachment of developer to a surface of a regulation member.SOLUTION: Developer forms a magnetic brush on an outer peripheral surface of a developing sleeve. A control part controlling the operation of a developing device executes, during a non-image forming period of an image forming apparatus, cleaning processing of rotating a developing sleeve while increasing magnetization of a magnetic brush formed at a position facing a regulation member 12 compared with that during an image forming period of the image forming apparatus.SELECTED DRAWING: Figure 12

Description

  The present disclosure relates to a developing device, an image forming apparatus, and a control method for the developing device.

  An electrophotographic image forming apparatus is widely used. In an electrophotographic image forming apparatus, an electrostatic latent image formed on a photoconductor is developed by supplying a developer to the photoconductor from a developing device. The developing device includes a developing roller that carries and transports the developer, and a regulating member for adjusting the transport amount of the developer.

  When the developer adheres to the regulating member, the gap between the regulating member and the developing roller decreases, and the amount of developer transported by the developing roller decreases. Japanese Patent Application Laid-Open No. 2015-036699 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2011-013248 (Patent Document 2) disclose a technique for recovering a developer attached to a regulating member.

JP2015-036699A JP 2011-013248 A

  In the techniques disclosed in Patent Documents 1 and 2 described above, the developer adhering to the surface of the regulating member is collected by forming a developer pool on the surface of the regulating member. However, these techniques cannot always sufficiently remove the developer from the surface of the regulating member, and further improvements are required.

  In the present disclosure, a developing device, an image forming apparatus, and a developing device control method that can suppress the adhesion of the developer to the surface of the regulating member are provided.

  According to one aspect of the present disclosure, a developing device that is used in an image forming apparatus that forms an image using a developer is provided. The developing device includes a developing roller, a regulating member, and a control unit. The developing roller has a developing sleeve and a plurality of magnetic poles. The developing sleeve is cylindrical. The plurality of magnetic poles are disposed along the inner peripheral surface of the developing sleeve. The regulating member regulates the thickness of the developer on the outer peripheral surface of the developing sleeve. The control unit controls the operation of the developing device. A magnetic brush is formed on the outer peripheral surface of the developing sleeve by the developer. The control unit executes a cleaning process when the image forming apparatus is not forming an image. The cleaning process is a process of rotating the developing sleeve in a state in which the magnetization of the magnetic brush formed at a position facing the regulating member is higher than that during image formation of the image forming apparatus.

  In the developing device, the developer includes toner and a carrier, and the control unit lowers the toner concentration of the developer that passes through a position facing the regulating member when the image forming apparatus is not forming an image.

  In the developing device, the image forming apparatus includes a photoconductor. The control unit prints the toner on the photosensitive member at a higher density when the image forming apparatus is not forming an image than when the image forming apparatus is forming an image.

  In the above-described developing device, when the image forming apparatus is not forming an image, the control unit peels off the developer whose toner density has been printed on the photosensitive member from the developing roller, and then supplies the developer again to the developing roller.

  In the developing device, the plurality of magnetic poles have a catch pole for holding the developer on the developing sleeve and a peeling pole for peeling the developer from the developing sleeve. The control unit moves the peeling electrode closer to the catch electrode when the image forming apparatus is not forming an image.

  The developing device further includes a supply roller that rotates to supply the developer to the developing roller. The control unit stops the rotation of the supply roller during non-image formation of the image forming apparatus.

  In the above developing device, the control unit rotates the developing sleeve to print the toner on the photosensitive member when the image forming apparatus is not forming an image, and then rotates the developing sleeve in the reverse direction.

  In the above developing device, the developing roller further includes a magnet roller provided to be rotatable with respect to the inner peripheral surface of the developing sleeve. The plurality of magnetic poles are arranged side by side in the circumferential direction of the magnet roller. The plurality of magnetic poles include a restriction pole disposed at a position facing the restriction member during image formation of the image forming apparatus, and another magnetic pole having a magnetic flux density larger than that of the restriction pole. The control unit moves the other magnetic pole to a position facing the regulating member when the image forming apparatus is not forming an image.

  In the developing device described above, the other magnetic pole is a main pole that is disposed at a position facing the photoconductor when the image is formed by the image forming apparatus.

  In the developing device described above, the control unit moves the other magnetic pole to a position facing the regulating member, and then rotates the developing sleeve in a direction opposite to the rotation direction when the image forming apparatus forms an image.

  In the above developing device, the control unit executes the cleaning process when the cumulative number of printed sheets by the developing apparatus or the number of printed sheets from the previous execution of the cleaning process reaches a predetermined number.

  According to one aspect of the present disclosure, an image forming apparatus including a photoreceptor and any one of the developing devices described above is provided.

  According to one aspect of the present disclosure, a method for controlling a developing device provided in an image forming apparatus that forms an image using a developer is provided. The developing device includes a developing roller and a regulating member. The developing roller has a developing sleeve and a plurality of magnetic poles. The developing sleeve is cylindrical. The plurality of magnetic poles are disposed along the inner peripheral surface of the developing sleeve. The regulating member regulates the thickness of the developer on the outer peripheral surface of the developing sleeve. A magnetic brush is formed on the outer peripheral surface of the developing sleeve by the developer. The control method includes a step of determining whether or not it is during image formation of the image forming apparatus, and a step of executing a cleaning process when it is determined in the determining step that the image forming apparatus is not forming an image. Yes. The cleaning process is a process of rotating the developing sleeve in a state in which the magnetization of the magnetic brush formed at a position facing the regulating member is higher than that during image formation of the image forming apparatus.

  In the above control method, the developer includes toner and a carrier. The step of executing the cleaning process includes a step of reducing the toner density of the developer that passes through the position facing the regulating member.

  In the above control method, the image forming apparatus includes a photoconductor. The step of executing the cleaning process includes a step of printing toner on the photosensitive member at a higher density than when the image forming apparatus forms an image.

  In the above control method, the cleaning process includes the steps of printing the toner on the photoconductor, peeling the developer having a reduced toner concentration from the developing roller, and peeling the developer from the developing roller. Supplying the developer to the developing roller again.

  In the above control method, each of the plurality of magnetic poles has a catch pole for holding the developer on the developing roller and a peeling pole for peeling the developer from the developing sleeve. The step of executing the cleaning process includes the step of moving the peeling electrode and bringing it closer to the catching electrode.

  In the above control method, the developing device further includes a supply roller that rotates to supply the developer to the developing roller. The step of executing the cleaning process includes a step of stopping the rotation of the supply roller.

  In the above control method, the step of executing the cleaning process includes a step of rotating the developing sleeve to print the toner on the photosensitive member, and a step of rotating the developing sleeve in the reverse direction after the printing step. .

  In the above control method, the developing roller further includes a magnet roller provided to be rotatable with respect to the inner peripheral surface of the developing sleeve. The plurality of magnetic poles are arranged side by side in the circumferential direction of the magnet roller. The plurality of magnetic poles include a restriction pole disposed at a position facing the restriction member during image formation of the image forming apparatus, and another magnetic pole having a magnetic flux density larger than that of the restriction pole. The step of executing the cleaning process includes a step of moving another magnetic pole to a position facing the restricting member.

  In the above control method, the other magnetic pole is a main pole disposed at a position facing the photoconductor during image formation of the image forming apparatus.

  In the control method described above, the cleaning process includes the steps of moving the other magnetic pole to a position facing the regulating member, and after the moving step, the developing sleeve is rotated in the direction of rotation of the image forming apparatus during image formation. Includes a step of rotating in the opposite direction.

  In the above control method, the cleaning process is executed when the cumulative number of printed sheets by the developing device or the number of printed sheets from the previous execution of the cleaning process reaches a predetermined number.

  According to the developing device, the image forming apparatus including the developing device, and the control method of the developing device according to the present disclosure, it is possible to suppress the adhesion of the developer to the surface of the regulating member.

1 is a schematic diagram illustrating a configuration of an image forming apparatus in which a developing device in an embodiment is used. It is a fragmentary sectional view showing the composition of the developing device in an embodiment. It is a side view which shows the structure of a developing roller and a control member. FIG. 4 is a schematic diagram illustrating a behavior of a developer during normal image formation of the image forming apparatus. It is a schematic diagram shown about a magnetic brush. FIG. 2 is a block diagram illustrating an outline of a system configuration of a developing device. FIG. 6 is a schematic diagram illustrating a regulating member at the start of use of the developing device. It is a schematic diagram showing adhesion of the developer to the tip of the regulating member. It is a schematic diagram which shows the control member after time. It is a flowchart explaining the conditions for performing the cleaning process of a control member. FIG. 6 is a first diagram illustrating cleaning of a regulating member in the first embodiment. FIG. 10 is a second diagram illustrating cleaning of the restriction member in the first embodiment. It is a flowchart which shows the 1st means to catch again a developing agent. It is a schematic diagram which shows the movement of the peeling pole within a magnet roller. FIG. 3 is a schematic diagram illustrating a developer in a housing during normal image formation. It is a flowchart which shows the 2nd means to catch again a developing agent. It is a schematic diagram which shows the developing agent in the housing at the time of the stop of a supply roller. 10 is a flowchart illustrating cleaning of a restriction member in the second embodiment. FIG. 6 is a schematic diagram showing a decrease in toner concentration of developer on the outer peripheral surface of the developing roller. FIG. 4 is a schematic diagram of a state in which a developer having a lowered toner concentration is faced to a regulating member. 10 is a flowchart illustrating cleaning of a restriction member in the third embodiment. It is a schematic diagram which shows rotation of a magnet roller. 7 is a graph showing changes in developer conveyance amount with respect to the number of printed sheets in Examples and Comparative Examples.

  Hereinafter, a developing device, an image forming apparatus, and a developing device control method according to an embodiment will be described with reference to the drawings. In the embodiments described below, the same or substantially the same configuration is denoted by the same reference numeral, and repeated description is not repeated. The configurations of the embodiments and modifications described below may be selectively combined as appropriate.

(Embodiment 1)
(Image forming apparatus 100)
FIG. 1 is a schematic diagram illustrating a configuration of the image forming apparatus 100. With reference to FIG. 1, a schematic configuration of an image forming apparatus 100 in which the developing device 5 in the embodiment is used will be described. The image forming apparatus 10 may be, for example, a color printer, a monochrome printer, or a multifunction printer (MFP: Multi-Functional Peripheral) of a monochrome printer, a color printer, and a fax machine.

  The photoreceptor 1 is an image carrier that carries a toner image. Around the photosensitive member 1, there are a cleaning device 2, a charging device 3, a writing device 4 (in the figure, only an arrow indicating scanning light from the writing device is shown), a developing device 5 (in FIG. 1, a developing roller 11 and a regulating member 12). Only the recording material 6 such as a transfer belt is disposed. Although known devices such as a paper feeding device and a fixing device are also provided, description thereof is omitted here.

  The photosensitive member 1, the charging device 3, and the developing roller 11 are rotationally driven by a driving unit (not shown), and the recording material 6 is conveyed. Rotation directions R1, R2, and R3 shown in FIG. 1 indicate directions in which the photoreceptor 1, the charging device 3, and the developing roller 11 rotate during normal image formation of the image forming apparatus 100, and are shown in FIG. The transport direction DR1 indicates a direction in which the recording material 6 is transported when the image forming apparatus 100 performs normal image formation.

  The charging device 3 uniformly charges the surface of the photoreceptor 1. The surface of the charged photoreceptor 1 is irradiated with scanning light from the writing device 4. As a result, an electrostatic latent image is formed on the surface of the photoreceptor 1. Developer is supplied from the developing device 5 to the electrostatic latent image, and the toner image is visualized on the surface of the photoreceptor 1. The toner image is transferred from the surface of the photoreceptor 1 to the recording material 6. The cleaning device 2 collects the toner remaining on the surface of the photoreceptor 1 after the toner image is transferred.

  The developer is a two-component developer containing toner and carrier. As the toner, toner obtained by attaching an external additive to toner base particles is used. The toner is formed of a non-magnetic material, and the carrier is formed of a magnetic material.

(Developing device 5)
FIG. 2 is a partial cross-sectional view illustrating a configuration of the developing device 5 according to the embodiment. With reference to FIG. 2, the structure of the developing device 5 provided in the image forming apparatus 100 shown in FIG. 1 will be described.

  The developing device 5 is a two-component developing device that develops the electrostatic latent image on the photoreceptor 1 and converts the electrostatic latent image into a visible toner image by reversal development with negatively charged toner particles.

  The developing device 5 has a housing 15 that accommodates the developer. A developing roller 11, a supply roller 13, and an agitation transport member 14 are accommodated in a predetermined position inside the housing 15 so as to be rotatable about a rotation axis with respect to the housing 15. The developing roller 11, the supply roller 13, and the stirring and conveying member 14 are arranged in parallel along the direction in which the respective rotation shafts extend (the direction perpendicular to the paper surface in FIG. 2).

  The agitating and conveying member 14 rotates in the housing 15 to agitate the developer and convey the developer to the supply roller 13. The supply roller 13 receives the developer conveyed from the agitating and conveying member 14 and supplies the developer toward the developing roller 11. The developer is circulated between the agitating / conveying member 14 and the supply roller 13 by rotating the agitating / conveying member 14 and the supply roller 13 in opposite directions.

  A restricting member 12 is disposed at a position facing a predetermined portion of the outer peripheral surface of the developing roller 11. One end of the regulating member 12 is fixed to the housing 15. The other end of the regulating member 12 is provided to face the outer peripheral surface of the developing roller 11. The regulating member 12 is, for example, a flat plate shape, and is arranged so that the small end surface is orthogonal to the outer peripheral surface of the developing roller 11. The regulating member 12 is arranged away from the outer peripheral surface of the developing roller 11. A gap is formed between the regulating member 12 and the developing roller 11.

  FIG. 3 is a side view showing the configuration of the developing roller 11 and the regulating member 12. As shown in FIG. 3, the developing roller 11 includes a magnet roller 20 and a developing sleeve 21. The magnet roller 20 has a solid cylindrical outer shape and has an outer peripheral surface 20A. The developing sleeve 21 has a hollow cylindrical shape and has an inner peripheral surface 21A and an outer peripheral surface 21B. The magnet roller 20 is accommodated in the developing sleeve 21.

  A magnet roller 20 is rotatably provided with respect to the developing sleeve 21 by a bearing (not shown). The magnet roller 20 is provided so as to be rotatable with respect to the inner peripheral surface 21 </ b> A of the developing sleeve 21. The developing sleeve 21 is provided so as to be rotatable with respect to the outer peripheral surface 20 </ b> A of the magnet roller 20. The magnet roller 20 and the developing sleeve 21 can be rotated relative to each other.

  The magnet roller 20 and the developing sleeve 21 can be rotated separately. The magnet roller 20 can rotate by receiving a rotational driving force from a driving source (not shown), and the developing sleeve 21 can also rotate. The magnet roller 20 and the developing sleeve 21 can rotate in both the clockwise and counterclockwise directions in the drawing. For the drive source of the magnet roller 20, it is preferable to use, for example, a device that can be driven forward and reverse and can control the rotational position, such as a stepping motor.

  The magnet roller 20 has a plurality of magnetic poles. The plurality of magnetic poles are included in the magnet roller 20. The plurality of magnetic poles are disposed along the inner peripheral surface 21 </ b> A of the developing sleeve 21. The plurality of magnetic poles are arranged side by side in the circumferential direction of the magnet roller 20 and the developing sleeve 21. In the present embodiment, five poles of a catch pole 22, a transport pole 23, a regulation pole 24, a main pole 25, and a peeling pole 26 are provided. Referring also to FIG. 2, the catch electrode 22, the regulation electrode 24, and the peeling electrode 26 are S poles, and the transport electrode 23 and the main electrode 25 are N poles. On the surface of the magnet roller 20, south pole magnetism and north pole magnetism are alternately arranged.

  The catch pole 22 attracts the developer supplied from the supply roller 13 by magnetic force, and holds the developer on the outer peripheral surface 21 </ b> B of the developing sleeve 21. Thereafter, the developer on the outer peripheral surface 21B of the developing sleeve 21 is conveyed to the conveying electrode 23 while being carried on the outer peripheral surface 21B of the developing sleeve 21. The developer maintains a state where the developer adheres to the outer peripheral surface 21 </ b> B of the developing sleeve 21 by the transport electrode 23.

  A regulating electrode 24 is disposed at a position where the outer circumferential surface of the developing roller 11 or the outer circumferential surface 21 </ b> B of the developing sleeve 21 faces the regulating member 12. When the developer that has received the magnetic force from the regulating pole 24 passes through the gap between the developing roller 11 and the regulating member 12, the thickness on the outer peripheral surface 21 </ b> B of the developing sleeve 21 is regulated by the regulating member 12. . Since the developer is rubbed off by the regulating member 12, the uniformity of the transport amount of the developer is improved.

  The developer is conveyed to the main electrode 25 after passing through the regulation electrode 24. The main pole 25 is disposed at a position facing the photoreceptor 1 (FIG. 1). The main pole 25 is configured to have a magnetic flux density larger than that of the regulation pole 24. When the developer passes through the position of the main electrode 25, only the toner out of the toner and carrier contained in the developer adheres to the photoreceptor 1. As a result, the electrostatic latent image formed on the photoreceptor 1 is developed as a toner image.

  Thereafter, the developer remaining on the outer peripheral surface 21 </ b> B of the developing sleeve 21 is conveyed to the peeling electrode 26 of the magnet roller 20. The peeling pole 26 is a magnetic pole for peeling the developer from the developing sleeve 21. The developer that has reached the peeling pole 26 tries to move to the catch pole 22 on the downstream side in the rotation direction by the conveying force of the developing sleeve 21, but the peeling pole 26 is the S pole and the catch pole 22 is also the S pole. A repulsive force acts between the peeling electrode 26 and the catch electrode 22, and the developer cannot move to the catch electrode 22. As a result, the developer peels from the developing sleeve 21 and falls to the lower housing 15.

  FIG. 4 is a schematic diagram illustrating the behavior of the developer during normal image formation of the image forming apparatus 100. The developer D1 shown in FIG. 4 is a developer supplied from the supply roller 13 to the developing roller 11 at the catch electrode 22. The developer D <b> 2 is a developer on the surface of the photoreceptor 1 that is supplied from the developing roller 11 at the position of the main electrode 25. The developer D3 is a developer remaining on the outer peripheral surface of the developing roller 11 after being supplied to the photoreceptor 1 at the main electrode 25.

  The developer D1 is in a state of being agitated and mixed by the rotation of the supply roller 13 and the agitating / conveying member 14, and has a high toner concentration. Toner is printed on the photoreceptor 1 at the position of the main electrode 25, and the toner in the developer D <b> 1 moves to the photoreceptor 1. Therefore, the toner concentration of the developer D3 existing downstream of the position of the main pole 25 in the rotation direction of the developing sleeve 21 is relatively low. The developer D3 has a lower toner concentration in the developer than the developer D1. In the developer D3, the concentration of the carrier that is a magnetic material is high.

  As described above, the developer peels from the developing sleeve 21 at the position of the peeling electrode 26. The developer that is peeled from the developing sleeve 21 at the position of the peeling electrode 26 is the developer D3 having a reduced toner concentration. The developer D3 peeled from the developing sleeve 21 moves around the supply roller 13 along the arrow AR0 in FIG. The developer D3 having a lowered toner concentration is agitated and mixed with the developer in the housing 15 by the supply roller 13. Thereby, the toner concentration of the developer D3 is increased. The developer whose toner density has been recovered adheres to the developing roller 11 again at the catch pole 22 of the developing roller 11.

(Magnetic brush 70)
FIG. 5 is a schematic diagram showing the magnetic brush 70. As described above, the developer including the toner and the carrier is attracted by the magnetic force of the catch pole 22 and is held on the outer peripheral surface 21 </ b> B of the developing sleeve 21. The developer is conveyed in the clockwise direction in the drawing by the rotation of the developing sleeve 21. When the developer passes through the gap between the developing roller 11 and the regulating member 12, the conveying amount of the developer is regulated by the regulating member 12. As schematically shown in FIG. 5, the developer held on the outer peripheral surface 21 </ b> B of the developing sleeve 21, in particular, a carrier that is a magnetic material, forms spikes along the magnetic force lines 71 formed by the magnetic poles of the magnet roller 20. doing. A magnetic brush 70 is formed by the ears.

(System configuration of developing device 5)
FIG. 6 is a block diagram showing an outline of the system configuration of the developing device 5. As illustrated in FIG. 6, the developing device 5 includes a developing device control unit 30 that controls the operation of the developing device 5. The developing device control unit 30 includes a timer 31 and a memory 39. The developing device control unit 30 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown).

  The developing device controller 30 includes a developing sleeve driving unit 32, a magnet roller driving unit 33, a supply roller driving unit 34, an agitating / conveying member driving unit 35, a magnetic pole moving unit 38, a developing sleeve angle sensor 36, A magnet roller angle sensor 37 is connected.

  The developing sleeve driving unit 32 is connected to the developing sleeve 21 and rotates or stops the developing sleeve 21. The magnet roller driving unit 33 is connected to the magnet roller 20 and rotates or stops the magnet roller 20. The supply roller drive unit 34 is connected to the supply roller 13 and rotates or stops the supply roller 13. The agitating / conveying member driving unit 35 is connected to the agitating / conveying member 14 and rotates or stops the agitating / conveying member 14. The magnetic pole moving unit 38 changes the arrangement of the plurality of magnetic poles of the magnet roller 20 within the magnet roller 20.

  The developing sleeve angle sensor 36 detects the rotation angle of the developing sleeve 21. The magnet roller angle sensor 37 detects the rotation angle of the magnet roller 20. The developing sleeve angle sensor 36 and the magnet roller angle sensor 37 may be, for example, a rotary encoder.

  The developing device control unit 30 is also electrically connected to a main controller 130 that controls the entire image forming apparatus 100. The developing device control unit 30 may constitute a part of the main controller 130.

(Adhesion of developer to the regulating member 12)
Next, a phenomenon in which the developer adheres to the regulating member 12 over time as the developing device 5 is used will be described. FIG. 7 is a schematic diagram showing the regulating member 12 at the start of use of the developing device 5. As shown in FIG. 7, at the start of use of the developing device 5, a gap having a length Db is formed between the outer peripheral surface of the developing roller 11 (the outer peripheral surface 21 </ b> B of the developing sleeve 21) and the regulating member 12. ing. A gap between the outer peripheral surface of the developing roller 11 and the regulating member 12 is referred to as a regulating gap.

  In FIG. 7, a virtual circle V that passes through the tip of the regulating member 12 on the most upstream side in the rotation direction R3 of the developing roller 11 during normal image formation and that is centered on the rotation center of the developing roller 11 is illustrated by a broken line. ing.

  The magnetic brush 70 shown in FIG. 5 is conveyed in the rotation direction R3 as the developing sleeve 21 rotates. When the magnetic brush 70 collides with the restricting member 12, the height of the magnetic brush 70 rising from the outer peripheral surface 21B of the developing sleeve 21 is restricted. The tip of the magnetic brush 70 moves to the downstream side in the rotational direction R3 along the virtual circle V shown in FIG.

  FIG. 8 is a schematic diagram showing the adhesion of the developer to the tip of the regulating member 12. Since the height of the magnetic brush 70 is regulated by the regulating member 12, the magnetic brush 70 does not pass through a region outside the virtual circle V on the downstream side in the rotation direction R <b> 3. As a result, as shown in FIG. 8, the attached developer 91 exists in the range downstream of the front end of the regulating member 12 in the rotation direction R <b> 3. First, the toner external additive adheres to the regulating member 12, and then the toner and the carrier adhere to the external additive layer, so that the adhered developer 91 adheres to the regulating member 12 and the developer aggregates. To do.

  FIG. 9 is a schematic diagram showing the regulating member 12 after time. As shown in FIG. 9, on the most upstream side in the rotation direction R3 of the regulating member 12, the regulating gap having the length Db is maintained even after the passage of time. On the other hand, on the downstream side of the regulating member 12 in the rotation direction R3, the developer is omitted from the tip of the regulating member 12, thereby narrowing the regulating gap and forming a regulating gap having a length Db1 smaller than the length Db. The When the regulation gap decreases in this way, the amount of developer transported by the developing roller 11 decreases.

  Further, as shown in FIG. 9, the toner stain 99 also adheres to the downstream surface of the regulating member 12 in the rotation direction R3. Toner scattering occurs when the developer passes through the regulating member 12 and when the toner is developed on the photoreceptor 1. The scattered toner adheres to the surface on the downstream side of the regulating member 12, thereby causing toner contamination 99. If the toner stain 99 drops off from the regulating member 12 and adheres to the developing roller 11, it causes image unevenness.

(Cleaning of the regulating member 12)
The developing device 5 of the embodiment provides various means for appropriately removing the adhered developer 91 and the toner stain 99 from the surface of the regulating member 12 when the image forming apparatus 100 is not forming an image.

  FIG. 10 is a flowchart for explaining conditions for executing the cleaning process of the regulating member 12. As shown in FIG. 10, first, in step S100, it is determined whether or not the cumulative number of printed sheets of the image forming apparatus 100 has reached a predetermined number. 6 receives a signal indicating the current cumulative number of prints from the main controller 130 of the image forming apparatus 100, and compares it with a threshold for the cumulative number of prints stored in the memory 39.

  If it is determined that the cumulative number of printed sheets has not reached the predetermined number (NO in step S100), then in step S200, the number of printed sheets of image forming apparatus 100 from the previous cleaning process of regulating member 12 has reached the predetermined number. Determine whether or not. 6 receives a signal indicating the number of printed sheets after the previous cleaning process from the main controller 130 of the image forming apparatus 100, and compares it with a threshold value of the number of printed sheets stored in the memory 39.

  When it is determined that the cumulative number of printed sheets of image forming apparatus 100 has reached a predetermined number (YES in step S100), or it has been determined that the number of printed sheets of image forming apparatus 100 since the previous cleaning process has reached a predetermined number. In the case (YES in step S200), the process proceeds to step S300, and the cleaning process of the regulating member 12 is executed.

  If the cumulative number of printed sheets of image forming apparatus 100 has not reached the predetermined number (NO in step S100), and the number of printed sheets from the previous cleaning process has not reached the predetermined number (NO in step S200), the regulating member No cleaning process 12 is executed, and the process ends as it is (end).

  FIG. 11 is a first diagram illustrating cleaning of the regulating member 12 in the first embodiment. As described above, at the position of the main electrode 25, only the toner out of the toner and the carrier contained in the developer adheres to the photoreceptor 1. The developer D3 has a lower toner concentration in the developer than the developer D1. In the first embodiment, after the image forming apparatus 100 performs non-image formation, as shown by an arrow AR <b> 1 in FIG. 11, the developer whose toner concentration has decreased is peeled off from the developing roller 11 at the position of the peeling electrode 26. The toner concentration in the developer around the developing roller 11 is lowered by supplying the toner again to the developing roller 11.

  FIG. 12 is a second diagram illustrating cleaning of the regulating member 12 in the first embodiment. While the developer whose toner density has decreased is re-caught by the catch pole 22, the rotation of the developing roller 11 in the rotation direction R3 is continued, and the rotation of the photoconductor 1 in the rotation direction R1 is continued. The toner continues to move from the developing roller 11 to the photoreceptor 1 at the position of the main electrode 25, and the toner concentration in the developer around the developing roller 11 is further reduced by continuing to re-catch the developer whose toner concentration has decreased. To do.

  As a result, the toner concentration in the developer conveyed at the position facing the regulating member 12 is lowered. In the developer having a lowered toner concentration, the concentration of the carrier in the developer is higher than that during normal image formation. Since the concentration of the carrier, which is a magnetic material, is higher than that during normal image formation, the magnetic property of the developer is increased. Thereby, the magnetization of the magnetic brush 70 formed at the position facing the regulating member 12 is increased, and the height at which the magnetic brush 70 rises from the outer peripheral surface of the developing roller 11 is increased more than usual. Moreover, the harder magnetic brush 70 is formed by improving the bonding force between the carriers.

  Therefore, the magnetic brush 70 can efficiently scrape the attached developer 91 adhering to the tip of the restricting member 12 and also remove the toner stain 99 adhering to the downstream surface of the restricting member 12. Can do. Since it becomes possible to more reliably remove the developer from the surface of the regulating member 12 when the image forming apparatus 100 is not forming an image, it is possible to suppress the developer from adhering to the surface of the regulating member 12 even after the passage of time. .

  By regularly performing the cleaning process of the restricting member 12, it is possible to suppress the narrowing of the restricting gap described with reference to FIG. 9, and thus it is possible to suppress a decrease in the developer transport amount by the developing roller 11. Therefore, it is possible to suppress a decrease in image quality due to a decrease in developer conveyance amount.

  A first means for re-catching the developer peeled from the developing roller 11 will be described. FIG. 13 is a flowchart showing a first means for re-catching the developer.

  Referring to FIG. 13, in step S <b> 311, it is determined whether or not the image forming apparatus 100 is in image formation. If it is determined that it is not during image formation (NO in step S311), then in step S312, the peeling electrode 26 is moved. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for moving the peeling pole 26 to the magnetic pole moving unit 38. The magnetic pole moving unit 38 that has received the control signal moves the peeling pole 26.

  FIG. 14 is a schematic diagram showing movement of the separation pole 26 in the magnet roller 20. FIG. 14 illustrates the arrangement of magnetic poles in the developing roller 11 when the image forming apparatus 100 is not forming an image. In FIG. 14, the position of the peeling electrode 26 at the time of normal image formation is indicated by a broken line. At the time of non-image formation of the image forming apparatus 100, as shown in FIG. The separation electrode 26 is moved closer to the catch electrode 22 and the distance between the separation electrode 26 and the catch electrode 22 is reduced.

  Next, in step S313, the developing sleeve 21 is rotated. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for rotating the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve driving unit 32 that has received the control signal rotates the developing sleeve 21 in the rotation direction R3. As the developing sleeve 21 rotates in the rotation direction R3, toner printing on the photosensitive member 1 is started.

  Since the peeling pole 26 is close to the catch pole 22, the position where the developer peels from the developing roller 11 has moved to the downstream side in the rotation direction R <b> 3. As a result, the developer peeled from the developing roller 11 at the position of the peeling electrode 26 is easily re-caught by the catch electrode 22. Therefore, the developer having a lowered toner concentration can be efficiently re-caught, and the toner concentration during development around the developing roller 11 can be quickly lowered.

  Subsequently, in step S314, it is determined whether or not a predetermined time has elapsed. If the predetermined time has not elapsed (NO in step S314), the determination in step S324 is repeated. Thereby, the rotation of the developing sleeve 21 is maintained for a predetermined time, and the cleaning process of the regulating member 12 is continued.

  When the predetermined time has elapsed (YES in step S314), the rotation of the developing sleeve 21 is stopped in step S315. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for stopping the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve 21 that has received the control signal stops rotating. Thereby, the printing of the toner on the photoreceptor 1 is completed.

  Next, in step S316, the peeling electrode 26 is moved to the original position. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for moving the peeling pole 26 to the magnetic pole moving unit 38. The magnetic pole moving unit 38 that has received the control signal moves the peeling pole 26 to a position indicated by a broken line in FIG. Then, the cleaning process ends (end).

  If it is determined in step S311 that the image forming apparatus 100 is in the process of forming an image (YES in step S311), the cleaning process is not executed and the process ends as it is (end).

  A second means for re-catching the developer peeled from the developing roller 11 will be described. FIG. 15 is a schematic diagram showing the developer in the housing 15 during normal image formation.

  FIG. 15 shows the developer level S in the housing 15 during normal image formation. During normal image formation, the supply roller 13 rotates, whereby the developer is stirred and mixed, and the developer whose toner density has been recovered is supplied to the development roller 11. An arrow AR2 shown in FIG. 12 indicates a moving path of the developer that is peeled off from the peeling electrode 26.

  FIG. 16 is a flowchart showing a second means for re-catching the developer. Referring to FIG. 16, in step S <b> 321, it is determined whether or not it is during image formation by image forming apparatus 100. If it is determined that it is not during image formation (NO in step S321), then in step S322, rotation of supply roller 13 is stopped. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for stopping the supply roller 13 to the supply roller driving unit 34. The supply roller driving unit 34 that has received the control signal stops the supply roller 13.

  When the image forming apparatus 100 is not forming an image, the rotation of the supply roller 13 is stopped. When the rotation of the supply roller 13 is stopped, the supply roller 13 no longer stirs the developer, so that the developer peeled off from the development roller 11 accumulates around the supply roller 13. FIG. 17 is a schematic diagram illustrating the developer in the housing 15 when the supply roller 13 is stopped. A developer D4 shown in FIG. 17 indicates a developer having a low toner concentration that has accumulated around the supply roller 13. The developer D4 is present closer to the developing roller 11 than the liquid level S shown in FIG. The developer D4 is present at a position closer to the catch electrode 22 than the liquid level S during normal image formation.

  As a result, the developer D4 is easily caught again by the catch electrode 22. An arrow AR3 shown in FIG. 17 indicates a movement path of the developer D4 attracted to the catch electrode 22. In this way, the developer having a lowered toner concentration can be efficiently re-caught, and the toner concentration during development around the developing roller 11 can be rapidly reduced.

  Returning to FIG. 16, next, in step S323, the developing sleeve 21 is rotated. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for rotating the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve driving unit 32 that has received the control signal rotates the developing sleeve 21 in the rotation direction R3. As the developing sleeve 21 rotates in the rotation direction R3, toner printing on the photosensitive member 1 is started.

  Subsequently, in step S324, it is determined whether or not a predetermined time has elapsed. If the predetermined time has not elapsed (NO in step S324), the determination in step S324 is repeated. Thereby, the rotation of the developing sleeve 21 is maintained for a predetermined time, and the cleaning process of the regulating member 12 is continued.

  When the predetermined time has elapsed (YES in step S324), the rotation of the developing sleeve 21 is stopped in step S325. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for stopping the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve 21 that has received the control signal stops rotating. Thereby, the printing of the toner on the photoreceptor 1 is completed. Then, the cleaning process ends (end).

  If it is determined in step S321 that the image forming apparatus 100 is in image formation (YES in step S321), the cleaning process is not executed, and the process ends (end).

  The toner is printed on the photoreceptor 1 by the rotation of the developing sleeve 21 in the rotation direction R3 in step S313 shown in FIG. 13 and the rotation of the developing sleeve 21 in the rotation direction R3 in step S323 shown in FIG. At this time, it is desirable to print the toner on the photosensitive member 1 at a higher density than when the image forming apparatus 100 normally forms an image. By printing a high-concentration toner on the photoreceptor 1, the toner concentration of the developer around the developing roller 11 can be reduced in a short time, so that the effect of scraping off the dirt of the regulating member 12 by the magnetic brush 70 is increased. In addition, the time required for the cleaning process of the regulating member 12 can be shortened.

  The electrostatic latent image formed on the photoconductor 1 may be a solid image so that the toner adhering to the developing roller 11 moves 100% toward the photoconductor 1 when performing the cleaning process. A method for adjusting the charge amount of the toner to facilitate the movement of the toner from the developing roller 11 to the photoreceptor 1, a method for adjusting the strength of the electric field applied to hold the toner on the developing roller 11, and the writing device 4 Appropriate control such as a method of adjusting the high intensity when exposing the photoreceptor 1 may be performed.

(Embodiment 2)
FIG. 18 is a flowchart for explaining the cleaning of the regulating member 12 in the second embodiment.

  Referring to FIG. 18, in step S331, it is determined whether or not the image forming apparatus 100 is in image formation. If it is determined that it is not during image formation (NO in step S331), then in step S332, the developing sleeve 21 is rotated forward. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for rotating the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve driving unit 32 that has received the control signal rotates the developing sleeve 21 in the rotation direction R3. As the developing sleeve 21 rotates in the rotation direction R3, toner printing on the photosensitive member 1 is started.

  FIG. 19 is a schematic diagram showing a decrease in the toner concentration of the developer on the outer peripheral surface of the developing roller. By developing the developing sleeve 21 forward and developing the toner at the position of the main pole 25, as described above, the development of the region from the main pole 25 to the peeling pole 26 downstream of the main pole 25 in the rotation direction R3. The toner concentration of the agent D3 decreases.

  Next, in step S333, the developing sleeve 21 is reversely rotated. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for rotating the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve driving unit 32 that has received the control signal rotates the developing sleeve 21 in the reverse rotation direction R3r. When the rotation of the developing sleeve 21 in the rotation direction R3 is stopped, the printing of the toner on the photosensitive member 1 is completed.

  Subsequently, in step S334, the developing sleeve 21 is stopped. 6 receives from the developing sleeve angle sensor 36 a signal indicating the angle at which the developing sleeve 21 is rotated. Upon receiving a signal indicating that the developing sleeve 21 has been rotated by a predetermined angle in the reverse rotation direction R3r, the developing device control unit 30 transmits a control signal for stopping the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve driving unit 32 that has received the control signal stops the developing sleeve 21.

  FIG. 20 is a schematic diagram of a state in which the developer having a lowered toner concentration faces the regulating member 12. From the state shown in FIG. 19 in which the toner concentration in the developer has decreased in part around the developing roller 11, the reverse rotation direction R3r (counterclockwise in the figure) opposite to the rotation direction R3 (clockwise in the figure). Direction), the developing roller 11 is rotated. The developer whose toner density has been reduced by the development on the photoreceptor 1 is conveyed to a position facing the regulating member 12 as the developing roller 11 rotates in the reverse direction.

  As a result, the toner concentration in the developer passing through the position facing the regulating member 12 is lowered. In the developer having a lowered toner concentration, the concentration of the carrier in the developer is higher than that during normal image formation. When the concentration of the carrier, which is a magnetic substance, is higher than usual, the magnetic property of the developer is increased. As a result, the magnetic brush 70 formed at a position facing the regulating member 12 is removed from the outer peripheral surface of the developing roller 11. Standing height is higher than usual. Therefore, the magnetic brush 70 can scrape the attached developer 91 attached to the tip of the regulating member 12.

  As the developing roller 11 rotates in the direction opposite to that during image formation, the magnetic brush 70 having an increased height is surely brought into contact with the toner stain 99 adhering to the regulating member 12. Therefore, the toner stain 99 generated on the downstream surface of the regulating member 12 can be easily removed.

  In this way, the developer can be more reliably removed from the surface of the regulating member 12 during non-image formation of the image forming apparatus 100. Therefore, the developer adheres to the surface of the regulating member 12 even after the passage of time. Can be suppressed.

  In this way, the cleaning process of the restricting member 12 is executed, and the process ends (END).

  If it is determined in step S331 that the image forming apparatus 100 is in the process of image formation (YES in step S331), the cleaning process is not executed and the process ends as it is (end).

(Embodiment 3)
FIG. 21 is a flowchart illustrating cleaning of the restriction member 12 according to the third embodiment.

  Referring to FIG. 21, in step S341, it is determined whether or not the image forming apparatus 100 is in image formation. If it is determined that it is not during image formation (NO in step S341), then in step S342, the magnet roller 20 is rotated. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for rotating the magnet roller 20 to the magnet roller driving unit 33. The magnet roller driving unit 33 that has received the control signal rotates the magnet roller 20 by a predetermined angle. The developing device control unit 30 receives a signal indicating the angle at which the magnet roller 20 is rotated from the magnet roller angle sensor 37.

  FIG. 22 is a schematic diagram showing the rotation of the magnet roller 20. FIG. 22 illustrates the arrangement of magnetic poles in the developing roller 11 when the image forming apparatus 100 is not forming an image.

  In the arrangement at the time of normal image formation shown in FIG. 3, among the plurality of magnetic poles of the magnet roller 20, the regulation pole 24 is arranged at a position facing the regulation member 12. On the other hand, when the image forming apparatus 100 is not forming an image, the main roller 25 is moved to a position facing the regulating member 12 by rotating the magnet roller 20 by a predetermined angle in the counterclockwise direction in the drawing.

  After the main pole 25 having a larger magnetic flux density than the regulation pole 24 is moved to a position facing the regulation member 12, the developing sleeve 21 is rotationally driven in step S343. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for rotating the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve driving unit 32 that has received the control signal rotates the developing sleeve 21.

  Since the main pole 25 has a magnetic flux density higher than that of the regulation pole 24, the magnetization of the magnetic brush 70 formed at a position facing the regulation member 12 is increased, and the magnetic brush 70 rises from the outer peripheral surface of the developing roller 11. More than usual. By rotating the developing sleeve 21 in this state, the magnetic brush 70 can scrape the adhered developer 91 adhering to the tip of the regulating member 12.

  The direction in which the developing sleeve 21 rotates at this time is not the rotation direction R3 but the reverse rotation direction R3r. Since the peeling pole 26 has moved to the upstream side in the rotation direction R3 as compared with normal image formation, the developer peeled off from the developing roller 11 may not be accommodated in the developing device 5 depending on the shape of the developing device 5, and image formation is performed. There is a possibility that the inside of the apparatus 100 may be stained with the developer. By rotating the developing sleeve 21 in the rotation direction R3, scattering of the developer into the image forming apparatus 100 can be suppressed.

  Subsequently, in step S344, it is determined whether or not a predetermined time has elapsed. If the predetermined time has not elapsed (NO in step S344), the determination in step S344 is repeated. Thereby, the rotation of the developing sleeve 21 is maintained for a predetermined time, and the cleaning process of the regulating member 12 is continued. When the predetermined time has elapsed (YES in step S344), the developing sleeve 21 is stopped in step S345. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for stopping the developing sleeve 21 to the developing sleeve driving unit 32. The developing sleeve 21 that has received the control signal stops rotating.

  Thereafter, in step S346, the magnet roller 20 is rotated to the original position. The developing device control unit 30 illustrated in FIG. 6 transmits a control signal for rotating the magnet roller 20 to the magnet roller driving unit 33. The magnet roller driving unit 33 that has received the control signal rotates the magnet roller 20 by a predetermined angle. Then, the cleaning process ends (end).

  If it is determined in step S341 that the image forming apparatus 100 is in the process of image formation (YES in step S341), the cleaning process is not executed and the process ends as it is (end).

  Examples will be described below. Using an image forming apparatus (full color multifunction machine bizhub C368) manufactured by Konica Minolta, image formation was performed under the conditions of a temperature of 23 ° C. and a humidity of 65%, and the durability transition of the developer conveyance amount on the developing roller was measured.

  In Example 1, as described in Embodiment 1, the cleaning process of the regulating member 12 was performed by reducing the toner concentration in the developer around the developing roller 11. During the non-image formation of the image forming apparatus 100, a solid patch was continuously printed over the entire width of the developing roller 11 for 30 seconds. Thereafter, the developing sleeve 21 was continuously rotated in the rotation direction R3 for 10 minutes. The rotational speed of the developing sleeve 21 at this time was set to the maximum speed at which the developing sleeve 21 can rotate. The cleaning process was performed every time 100,000 sheets were printed.

  In Example 2, as described in Embodiment 2, the cleaning process of the regulating member 12 was performed by rotating the developing roller 11 in the reverse direction. During the non-image formation of the image forming apparatus 100, the solid patch was printed for the length of a quarter of the circumference of the developing roller 11 with the full width of the developing roller 11. Thereafter, the developing roller 11 was rotated in the reverse rotation direction R3r by one turn of the developing roller 11. The rotational speed of the developing sleeve 21 at this time was set to the maximum speed at which the developing sleeve 21 can rotate. The cleaning process was performed every time 500 sheets were printed. In the second embodiment, the cleaning process is frequently performed because the force for scraping off the dirt of the regulating member 12 is smaller than that in the first embodiment.

  In Example 3, as described in the third embodiment, the cleaning process of the regulating member 12 was performed by rotating the magnet roller 20 and changing the arrangement of the magnetic poles. During non-image formation of the image forming apparatus 100, the magnetic roller 20 was rotated to change the arrangement of the magnetic poles, and then the developing sleeve 21 was rotated in the reverse rotation direction R3r for 10 seconds. The rotational speed of the developing sleeve 21 at this time was set to the maximum speed at which the developing sleeve 21 can rotate. The cleaning process was performed every time 1000 sheets were printed. In the third embodiment, since the force for scraping off the dirt of the regulating member 12 is smaller than that of the first embodiment and larger than that of the second embodiment, the frequency of executing the cleaning process is also the frequency between the first and second embodiments. did.

  In the comparative example, image formation was continued without executing the cleaning process of the regulating member 12.

  FIG. 23 is a graph showing a change in developer conveyance amount with respect to the number of printed sheets in Examples and Comparative Examples. The horizontal axis in FIG. 23 indicates the number of printed sheets. The vertical axis in FIG. 23 indicates the developer transport amount on the developing roller.

  In the comparative example, in the range where the number of printed sheets shown in FIG. 23 is N1, the external additive in the developer adhered to the downstream side in the rotational direction at the tip of the regulating member 12. In the range where the number of printed sheets was N2, toner and carrier adhered to the external additive. Due to this adhesion, the size of the gap between the outer peripheral surface of the developing roller 11 and the regulating member 12 is reduced, and as a result, the developer conveyance amount is reduced as shown in FIG. In the range where the number of printed sheets is N3, the adhesion of the toner and the carrier is saturated. As a result, as shown in FIG. 23, the decrease in the transport amount of the developer is small.

  As shown in FIG. 23, as compared with the comparative example, in any of the examples, it was possible to suppress the decrease in the developer transport amount after the endurance. In any of the examples, image unevenness due to the removal of the toner stain 99 from the downstream surface of the regulating member 12 did not occur during the measurement of the durability transition of the developer conveyance amount.

  From the above, in the developing device 5 according to the embodiment, even if the developer adheres to the surface of the regulating member 12, the adhered developer can be removed from the surface of the regulating member 12 by executing the cleaning process. As a result, it was shown that the decrease in the developer conveyance amount can be suppressed through durability.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Photoconductor, 2 Cleaning apparatus, 3 Charging apparatus, 4 Writing apparatus, 5 Developing apparatus, 6 Recording material, 11 Developing roller, 12 Control member, 13 Supply roller, 14 Stirring conveyance member, 15 Housing, 20 Magnet roller, 20A, 21B outer peripheral surface, 21 developing sleeve, 21A inner peripheral surface, 22 catch pole, 23 transport pole, 24 regulating pole, 25 main pole, 26 peeling pole, 70 magnetic brush, 71 magnetic field lines, 91 adhering developer, 99 toner stain, 100 Image forming apparatus, D1, D2, D3, D4 developer, DR1 transport direction, R1, R2, R3 rotation direction, R3r reverse rotation direction.

Claims (23)

A developing device provided in an image forming apparatus that forms an image using a developer,
A cylindrical developing sleeve; and a developing roller having a plurality of magnetic poles arranged along the inner peripheral surface of the developing sleeve;
A regulating member that regulates the thickness of the developer on the outer peripheral surface of the developing sleeve;
A control unit for controlling the operation of the developing device,
A magnetic brush is formed on the outer peripheral surface of the developing sleeve by the developer,
The control unit rotates the developing sleeve in a state in which the magnetization of the magnetic brush formed at a position facing the regulating member is higher than that at the time of image formation by the image forming apparatus during non-image formation of the image forming apparatus. A developing device that executes a cleaning process. The developer includes a toner and a carrier,
The developing device according to claim 1, wherein the control unit lowers the toner concentration of the developer that passes through a position facing the regulating member when the image forming apparatus is not forming an image. The image forming apparatus includes a photoconductor,
The developing device according to claim 2, wherein the control unit prints the toner on the photoconductor at a higher density when the image forming apparatus is not forming an image than when the image forming apparatus is forming an image. The image forming apparatus includes a photoconductor,
The controller supplies the developer, which has been printed on the photosensitive member and has a lowered toner density, separated from the developing roller and then re-supplied to the developing roller during non-image formation of the image forming apparatus. The developing device according to claim 2 or 3. The plurality of magnetic poles include a catch pole for holding the developer on the developing sleeve, and a peeling pole for peeling the developer from the developing sleeve,
The developing device according to claim 4, wherein the control unit moves the peeling electrode closer to the catch electrode when the image forming apparatus is not forming an image. A feed roller for supplying the developer to the developing roller by rotating;
The developing device according to claim 4, wherein the control unit stops the rotation of the supply roller during non-image formation of the image forming apparatus. The image forming apparatus includes a photoconductor,
4. The control unit according to claim 2, wherein the control unit rotates the developing sleeve to print the toner on the photosensitive member during non-image formation of the image forming apparatus, and then rotates the developing sleeve in the reverse direction. 5. Development device. The developing roller further includes a magnet roller provided rotatably with respect to the inner peripheral surface of the developing sleeve, and the plurality of magnetic poles are arranged side by side in the circumferential direction of the magnet roller,
The plurality of magnetic poles include a regulation pole disposed at a position facing the regulation member during image formation of the image forming apparatus, and another magnetic pole having a magnetic flux density larger than the regulation pole,
The developing device according to claim 1, wherein the control unit moves the other magnetic pole to a position facing the regulating member when the image forming apparatus is not forming an image. The image forming apparatus includes a photoconductor,
The developing device according to claim 8, wherein the other magnetic pole is a main pole disposed at a position facing the photoconductor during image formation of the image forming apparatus.   The control unit, after moving the other magnetic pole to a position facing the regulating member, rotates the developing sleeve in a direction opposite to a rotation direction during image formation of the image forming apparatus. The developing device according to 1.   11. The control unit according to claim 1, wherein the control unit executes the cleaning process when a cumulative number of printed sheets by the developing device or a number of printed sheets from the previous execution of the cleaning process reaches a predetermined number. The developing device according to claim 1. A photoreceptor,
An image forming apparatus comprising: the developing device according to claim 1. A method of controlling a developing device provided in an image forming apparatus that forms an image using a developer,
The developing device includes:
A cylindrical developing sleeve; and a developing roller having a plurality of magnetic poles arranged along the inner peripheral surface of the developing sleeve;
A regulating member that regulates the thickness of the developer on the outer peripheral surface of the developing sleeve,
A magnetic brush is formed on the outer peripheral surface of the developing sleeve by the developer,
Determining whether it is during image formation of the image forming apparatus;
When it is determined in the determining step that the image forming apparatus is not forming an image, the magnetization of the magnetic brush formed at a position facing the regulating member is higher than that when the image forming apparatus is forming an image. And a step of executing a cleaning process of rotating the developing sleeve. The developer includes a toner and a carrier,
The developing device control method according to claim 13, wherein the step of executing the cleaning process includes a step of decreasing a toner concentration of the developer that passes through a position facing the regulating member. The image forming apparatus includes a photoconductor,
The method of controlling a developing device according to claim 14, wherein the step of executing the cleaning process includes a step of printing the toner on the photosensitive member at a higher density than when the image forming apparatus forms an image. The image forming apparatus includes a photoconductor,
The step of executing the cleaning process includes:
Printing the toner on the photoreceptor;
Peeling the developer having a reduced toner concentration from the developing roller;
The developing device control method according to claim 14, further comprising a step of supplying the developer peeled off from the developing roller in the peeling step to the developing roller again. The plurality of magnetic poles include a catch pole for holding the developer on the developing sleeve, and a peeling pole for peeling the developer from the developing sleeve,
The developing device control method according to claim 16, wherein the step of executing the cleaning process includes a step of moving the peeling electrode to approach the catching electrode. The developing device further includes a supply roller that rotates to supply the developer to the developing roller,
The developing device control method according to claim 16, wherein the step of executing the cleaning process includes a step of stopping the rotation of the supply roller. The image forming apparatus includes a photoconductor,
The step of executing the cleaning process includes:
Rotating the developing sleeve to print the toner on the photoreceptor;
The method for controlling a developing device according to claim 14, further comprising a step of rotating the developing sleeve in a reverse direction after the printing step. The developing roller further includes a magnet roller provided rotatably with respect to the inner peripheral surface of the developing sleeve, and the plurality of magnetic poles are arranged side by side in the circumferential direction of the magnet roller,
The plurality of magnetic poles include a regulation pole disposed at a position facing the regulation member during image formation of the image forming apparatus, and another pole having a magnetic flux density larger than the regulation pole,
The developing device control method according to claim 13, wherein the step of executing the cleaning process includes a step of moving the other magnetic pole to a position facing the restriction member. The image forming apparatus includes a photoconductor,
21. The developing device control method according to claim 20, wherein the other magnetic pole is a main pole disposed at a position facing the photoconductor during image formation of the image forming apparatus. The step of executing the cleaning process includes:
Moving the other magnetic pole to a position facing the regulating member;
The developing device control method according to claim 20 or 21, further comprising a step of rotating the developing sleeve after the moving step in a direction opposite to a rotation direction during image formation of the image forming apparatus.   23. The cleaning process is executed according to any one of claims 13 to 22, wherein the cleaning process is executed when the cumulative number of printed sheets by the developing device or the number of printed sheets from the previous execution of the cleaning process reaches a predetermined number. Method for controlling the developing device.

Images