JP5381230B2 - Two-component developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a two-component developing device having a developing sleeve surface cleaning mechanism used in an image forming apparatus such as an electrophotographic copying machine or printer, a process cartridge including the same, and an image forming apparatus equipped with the process cartridge. It is about.

In a developing device used in an electrophotographic image forming apparatus, the surface of the developing sleeve is subjected to friction stress of the developer on the image carrier and the developing sleeve during development or friction stress of the developer on the doctor blade and the developing sleeve. A phenomenon called sleeve fixation occurs in which a toner base, a toner WAX component, additives such as silica, and components such as paper powder are fixed on the developing sleeve. When such sleeve sticking occurs, inconveniences such as a decrease in image density at the sleeve fixing part and a bias charge-up at the sleeve fixing part occur.
The reduction in image density at the portion where the sleeve is fixed will be described. When the toner component having a negative charging characteristic is fixed to the sleeve, the developing sleeve has a negative charging characteristic. Then, since the electrostatic adhesion force between the developing sleeve having the negative charging characteristic and the carrier having the positive charging characteristic increases, the developer that has been pumped up and developed cannot be sufficiently cut off by the developer cutting pole.

Therefore, once the developer that has undergone development is rotated, the toner concentration of the developer pumped up by the developing sleeve becomes lower than the toner concentration in the developing device after the second rotation of the developing sleeve. Leading to a decline.
In addition, the bias charge-up at the sleeve fixing portion will be described. This is because the fixed object fixed to the sleeve becomes an insulating layer and becomes a dielectric layer, and the charge is held on the surface of the developing sleeve. This is a phenomenon in which the bias on the developing sleeve increases. As a result, the background potential is lowered, leading to the occurrence of soiling. Further, when the output of the charging bias is increased by controlling the anti-smudge, a high bias is applied to the photoconductor, which promotes fatigue of the photoconductor, and in some cases, discharge breaks, leading to generation of an abnormal image.
Therefore, various techniques have been proposed in the past in order to avoid inconveniences such as a decrease in image density at the fixed portion of the sleeve and a bias charge-up at the fixed portion of the sleeve, which occur in the developing device used in the electrophotographic image forming apparatus. (For example, see Patent Documents 1 to 4).

In Patent Document 1, the developer stripping means from the developer carrying member strips off the developer by using a pumping magnetic pole and an agent cutting pole (magnetic field generating means having a magnetic pole such as the pumping pole and the same-polarity carrying magnetic pole). A technique is disclosed in which the developer on the developer carrying member in the component developing apparatus is peeled off and the developer carrying member is cleaned with an elastic blade (cleaning member).
Patent Document 2 describes a developer with a pumping magnetic pole and an agent cutting pole (here, magnetic field generating means having a magnetic pole such as a stripping magnetic pole having the same polarity as the pumping magnetic pole is arranged in a fixed state). A technique is disclosed in which the developer on the developer carrier in the two-component developing device is stripped off, the toner adhering to the surface of the developer carrier is scraped off with a scraping member, and the developer carrier is cleaned. .
Patent Document 3 discloses a cleaning mechanism for a layer regulating member (doctor) that cleans a developing component with a cleaning member, in which a cleaning member surface has a file shape and moves in a longitudinal direction to perform a cleaning operation.
Japanese Patent Laid-Open No. 2004-260688 adjusts the filming removal operation of the image carrier by using a film thickness detection unit or a surface potential detection unit, and uses the surface potential detection unit to determine whether or not the developer carrier is cleaned. A technique for making a determination is disclosed.

However, the techniques of Patent Documents 1 and 2 only describe that the developer is peeled off, and with this technique, it is impossible to completely remove the developer from the developer carrier.
If even a small amount of developer remains on the sleeve surface, the developing sleeve cleaning member will be scratched and it will be difficult to ensure its life. In addition, since the positive contact between the developing sleeve cleaning member and the developing sleeve is hindered, the cleaning efficiency is also lowered.
Further, a technique for increasing the efficiency of removing the developer from the developer carrying member using a bias power source that causes the toner to fly is also disclosed. However, in such a technique, only the toner can fly and the carrier remains, or Since a power supply is required, side effects such as a complicated configuration, an increase in cost, and an increase in power consumption can be considered.
Further, the disclosure of Patent Document 3 is a technique relating to a cleaning mechanism for a layer regulating member (doctor), and the technique of Patent Document 4 is to determine whether or not the developer carrying member is cleaned using the surface potential detection means. Although there is no description of a specific method for detecting the surface potential.
In addition, if the developer remains on the surface of the developing sleeve when the developing sleeve is cleaned, the developing sleeve cleaning member is damaged, leading to a reduction in the service life and a reduction in cleaning efficiency.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a two-component developing device capable of improving the life of the developing sleeve cleaning member and improving the cleaning efficiency in consideration of the above-described circumstances, a process cartridge including the same, and an image on which the process cartridge is mounted. It is to provide a forming apparatus.

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a stirring mechanism for stirring a developer composed of toner and a magnetic carrier and supplying the developer in the vicinity of the developer carrying member, and a fixed arrangement A developer formed by a magnet roller having a developer cutting pole that is a gap between adjacent magnets having the same polarity of the magnetic field in which repulsive magnetic fields of the plurality of magnets are adjacent to each other, and a developer sleeve that covers the periphery of the magnet roller to the development position. In the two-component developing device comprising the developer carrying member to be carried and a control unit connected to the control device of the main body of the image forming apparatus, the control unit has at least the stirring mechanism at a specified job end. the drive is turned off, dropping a developer by the developer cutting electrode by the developing sleeve continues to turn on a predetermined time in the developing casing, the developing Stop the rotation of the sleeve, the time of the developing sleeve cleaning member is movable to cover the longitudinal direction of the developing sleeve installed in the developing casing is in contact on the surface of the developing sleeve, again, the developing sleeve and the predetermined time on The two-component developing device is characterized in that the developing sleeve is controlled to rotate.

The developing sleeve cleaning member may include an axial center and a cleaning portion that covers the axial center, and when the developing sleeve cleaning member comes into contact with the surface of the developing sleeve, The two-component developing device according to claim 1, wherein the developing sleeve cleaning member rotates reversely with respect to the developing sleeve.
According to a third aspect of the present invention, there is provided the two-component developing device according to the second aspect, wherein the cleaning portion has a brush shape.
According to a fourth aspect of the present invention, there is provided the two-component developing device according to the second or third aspect, wherein the cleaning portion is a melamine resin foam.
According to a fifth aspect of the present invention, a bias having a polarity opposite to that of the toner is applied to the shaft center of the developing sleeve cleaning member at a timing when the cleaning unit contacts the developing sleeve. A two-component developing device according to any one of the above.

According to a sixth aspect of the present invention, the control device of the main body of the image forming apparatus includes a function of storing an average of the image area ratio of the output image, and a value obtained by multiplying the non-image area ratio by the number of prints, 6. The two-component developing device according to claim 1, wherein a cleaning operation of the surface of the developing sleeve is executed when a value obtained by multiplying the non-image area ratio by the developing sleeve traveling time becomes a predetermined value. To do.
According to a seventh aspect of the invention, an optical sensor detects the surface of the developing sleeve exposed by dropping the developer into the developing casing, and when the detection result exceeds a prescribed threshold, 6. The two-component developing device according to claim 1, wherein the sleeve cleaning member performs a cleaning operation on the surface of the developing sleeve .
According to an eighth aspect of the present invention, the residual potential on the surface of the developing sleeve exposed by dropping the developer into the developing casing is measured by a potential sensor installed at a position opposed to the surface of the developing sleeve. 6. The two-component developing device according to claim 1, wherein the developing sleeve cleaning member performs a cleaning operation on the surface of the developing sleeve when the residual potential exceeds a predetermined threshold value.

According to a ninth aspect of the present invention, there is provided a process cartridge including an image carrier and a developing device, the process cartridge including the two-component developing device according to any one of the first to eighth aspects as the developing device. To do.
According to a tenth aspect of the present invention, the electrostatic latent image formed on the image carrier is visualized by developing with toner, the toner image is transferred onto a recording medium, and the toner image on the recording medium is transferred. In the image forming apparatus for fixing the image on the recording medium by heat and pressure, the process cartridge according to claim 9 is provided as the process cartridge including the image carrier.

According to an eleventh aspect of the present invention, there is provided an agitation mechanism for agitating a developer composed of toner and a magnetic carrier and supplying the developer in the vicinity of the developer carrying member, and repulsion of a plurality of fixed magnets. the developer carrying member for carrying a developer to be formed by the magnet roller and the developing sleeve covering the peripheral the magnet roller having the same polarity of the developer cutting pole magnet is interstice of adjacent magnetic fields mutually acts to the developing position And a control unit connected to a control device of the image forming apparatus main body, wherein the control device of the image forming apparatus main body is at least at a specified job end. and turning off the drive of the stirring mechanism, the developing casing developer in the developer cutting electrode by a developing sleeve continues to turn on a predetermined time To drop, the rotation of the developing sleeve is stopped, when the developing sleeve cleaning member is movable to cover the longitudinal direction of the developing sleeve installed in the developing casing is in contact on the surface of the developing sleeve, again, the developing sleeve And an image forming apparatus that controls to turn on the developing sleeve for a predetermined time.

According to a twelfth aspect of the present invention, the developing sleeve cleaning member includes an axial center and a cleaning portion that covers the axial center, and when the developing sleeve cleaning member contacts the developing sleeve surface, 12. The image forming apparatus according to claim 11, wherein the developing sleeve cleaning member rotates reversely with respect to the developing sleeve.
The invention according to claim 13 is the image forming apparatus according to claim 11, wherein the cleaning portion has a brush shape.
The invention according to claim 14 is the image forming apparatus according to claim 12 or 13, wherein the cleaning portion is a melamine resin foam.
According to a fifteenth aspect of the present invention, a bias having a polarity opposite to that of the toner is applied to the shaft center of the developing sleeve cleaning member at a timing when the cleaning unit contacts the developing sleeve. The image forming apparatus according to any one of the above.

According to a sixteenth aspect of the present invention, the control device of the main body of the image forming apparatus includes a function of storing an average of the image area ratio of the output image, and a value obtained by multiplying the non-image area ratio by the number of prints, or 16. The image forming apparatus according to claim 11, wherein a cleaning operation of the surface of the developing sleeve is executed when a value obtained by multiplying the non-image area ratio by a developing sleeve traveling time becomes a predetermined value. To do.
According to a seventeenth aspect of the present invention, an optical sensor detects the surface of the developing sleeve exposed by dropping the developer into the developing casing, and when the detection result exceeds a predetermined threshold, the developing sleeve 16. The image forming apparatus according to claim 11, wherein the sleeve cleaning member performs a cleaning operation on the surface of the developing sleeve .
In the invention according to claim 18, the residual potential on the surface of the developing sleeve exposed by dropping the developer into the developing casing is measured by a potential sensor installed at a position opposed to the surface of the developing sleeve. The image forming apparatus according to claim 11, wherein the developing sleeve cleaning member executes a cleaning operation on the surface of the developing sleeve when the residual potential exceeds a predetermined threshold value.

  According to the present invention, at the specified job end of the two-component developing device, the stirring mechanism is turned off, and the developer carrying member driving mechanism is kept on for a predetermined time, thereby developing the developer at the developer cutting pole. Since it is dropped into the casing and the developer is temporarily removed from the developing sleeve temporarily and the developing sleeve surface is exposed, the life of the developing sleeve cleaning member can be improved and the cleaning efficiency can be improved. it can.

1 is a schematic diagram illustrating an electrophotographic full-color printer as an image forming apparatus according to an exemplary embodiment. FIG. 2 is a cross-sectional view showing a first embodiment of a two-component developing device according to the present invention applied to the printer of FIG. 1. FIG. 3 is a schematic diagram illustrating a positional relationship between a developing sleeve extending in a longitudinal direction and a developing sleeve cleaning member as viewed from the left side surface of FIG. 2. FIG. 4 is a schematic view showing the developing sleeve and the developing sleeve cleaning member as viewed from the left side surface in the same manner as FIG. 3 showing the operation state of the developing sleeve cleaning member of FIG. 3. It is a block diagram explaining control of the two-component developing device by this invention. 6 is a flowchart showing a series of developing sleeve cleaning operations. FIG. 3 is a cross-sectional view showing a second embodiment of a two-component developing device according to the present invention applied to the printer of FIG. 1. It is the schematic which shows the cross-sectional shape of the developing sleeve cleaning member of FIG. It is a figure which shows the relationship between the developing sleeve cleaning time and developing sleeve surface density regarding a 1st embodiment and a 2nd embodiment with a graph. It is a figure which shows the relationship between the developing sleeve cleaning time and the developing sleeve surface density regarding a 1st embodiment, a 2nd embodiment, and a 3rd embodiment with a graph. It is sectional drawing which shows 4th Embodiment of the developing sleeve cleaning member used for a two-component developing device. It is a figure which shows the lifetime of the cleaning part of 3rd Embodiment and 4th Embodiment of a developing sleeve cleaning member with a graph. It is sectional drawing which shows 5th Embodiment of the developing sleeve cleaning member used for a two-component developing device. It is a figure which shows the relationship between the developing sleeve cleaning time and the developing sleeve surface density regarding a 1st embodiment, a 2nd embodiment, a 3rd embodiment, and a 5th embodiment with a graph. 14 is a flowchart showing a series of developing sleeve cleaning operations of the two-component developing device of FIG. 13. FIG. 16 is a graph showing the developing sleeve cleaning member and the cleaning of the developing sleeve surface at each job end by the operation in FIG. 15. It is sectional drawing which shows 7th Embodiment of the developing sleeve cleaning member used for a two-component developing device. 18 is a flowchart showing a series of developing sleeve cleaning operations of the two-component developing device of FIG. FIG. 19 is a graph showing the developing sleeve cleaning member and the cleaning of the developing sleeve surface at each job end by the operation in FIG. 18. It is sectional drawing which shows 8th Embodiment of the developing sleeve cleaning member used for a two-component developing device. 21 is a flowchart showing a series of developing sleeve cleaning operations of the two-component developing device of FIG. 20. It is a figure which shows the developing sleeve cleaning member by operation | movement in FIG. 21, and the cleaning of the developing sleeve surface in every job end in a graph.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an electrophotographic full-color printer as an image forming apparatus according to the present embodiment.
The image unit 10 of the printer A includes an intermediate transfer belt 11 as an image carrier that moves endlessly in the direction of an arrow. On the lower stretched surface of the intermediate transfer belt 11, four images that are toner image forming means are provided. Forming units 12Y, 12C, 12M and 12K are arranged.
Y, C, M, and K added to the number of the image forming unit correspond to the color of the toner to be handled. Y represents yellow, C represents cyan, M represents magenta, and K represents black. Similarly, Y, C, M, and K are attached to an image carrier (hereinafter referred to as a photosensitive drum) 8 that is provided in the image forming unit and rotates together with the intermediate transfer belt 11. The photosensitive drums 8Y to 8K are arranged at equal intervals so as to be in contact with a part of a stretched portion with the intermediate transfer belt 11 at least during image formation. The yellow (Y), cyan (C), magenta (M), and black (K) color toner images transferred to the intermediate transfer belt 11 are superimposed and fed from a paper feed unit 14 to a paper feed roller and a registration roller (not shown). The image is transferred using a secondary transfer roller 15 onto the sheet conveyed through the pair.
After the transfer, the toner image is fixed by the fixing unit 16 and is discharged out of the machine as it is in the case of single-sided image formation. In the case of double-sided image formation, a reversing path (not shown) is known as known. Through the double-sided portion (not shown), and again sent to the secondary transfer unit.

FIG. 2 is a sectional view showing a first embodiment of a two-component developing device according to the present invention applied to the printer of FIG. The two-component developing device 17 in FIG. 2 is a two-component developing device included in, for example, the image forming unit 12Y in FIG. 1 configured as a process cartridge.
In FIG. 1, Y, C, M, and K are added to the image forming unit number 12, but the two-component developing device 17 in FIG. 2 has the same configuration in each image forming unit 12Y (C, M, K). , Y, C, M, and K are not described.
The developing device 17 includes a developer carrying body 1 including a pump 6, a developer cutting pole 4, a magnet 6 having a developing pole (main electrode) 5, and the like, and a developing sleeve 7 covering the periphery of the magnet 6. A stirring mechanism 3 for supplying a developer to the pole 2, a layer thickness regulating member 9, a developing sleeve cleaning member 18, a movable mechanism 19 for the developing sleeve cleaning member 18, a developing casing 20, and the like. An image carrier 8 is disposed above the developing sleeve 7.
During the normal image forming operation of the developing device 17, the concentrations of the carrier and the replenishment toner in the developing casing 20 of the developing device 17 are kept uniform, and the developer is always supplied to the pumping electrode 2 of the developer carrier 1. A stirring mechanism 3 having a function, a magnetic developing sleeve 7 covering the periphery of a magnet 6 having a non-movable pumping pole 2, a developer cutting pole 4, a developing pole (main pole) 5, and the like, and a photoconductor as an image carrier Three with the drum 8 rotate in the direction of the arrow in the figure.

First, the developer moved to the vicinity of the pumping electrode 2 is pumped up while the pumping electrode 2 is being stirred by the stirring mechanism 3. The agitating mechanism 3 has two functions of agitating the developer and moving the developer to the very vicinity.
Next, the developer pumped up by the stirring mechanism 3 is regulated by the layer thickness regulating member 9, and the developer thickness is regulated by the development pole (main pole) 5 to the latent image written on the image carrier 8. Developed. After the development, the developer whose toner density has fluctuated (decreased) returns to the developing casing 20 at the developer cutting pole 4 and is stirred by the stirring mechanism 3 together with the replenishing toner. The above is a series of cycles, and image formation is performed in this continuous cycle.
Here, the developer cutting pole refers to a gap between adjacent magnets (N pole / N pole, or S pole / S pole in FIG. 2) adjacent to each other. Then, since a repulsive magnetic field works, the developer does not move around with the developing sleeve 7 but falls into the developing casing 20.
In the present invention, the driving of the stirring mechanism 3 is turned off for a predetermined time, and only the developing sleeve 7 is rotated without pumping up the developer, so that the developer only falls from the developer carrier 1. The developer is reliably removed from the surface of the developing sleeve 7.

By executing this operation, the developing sleeve 7 is completely exposed (the developer component <carrier> is not left on the developing sleeve 7), and the life of the developing sleeve cleaning member 18 is increased and the surface of the developing sleeve 7 is removed. Efficient cleaning becomes possible. If the developer component (here, carrier) remains on the surface of the developing sleeve 7 when the developing sleeve 7 is cleaned, the developing sleeve cleaning member 18 is damaged, and the life of the developing sleeve cleaning member 18 is shortened. descend.
Further, when the developer component (here, carrier) remains on the surface of the developing sleeve 7 when the developing sleeve 7 is cleaned, the carrier covers the surface of the developing sleeve 7, so that the adhering component (mainly the developing sleeve 7 surface). The toner component) cannot be efficiently cleaned.
When the developing sleeve 7 is cleaned, the movable mechanism 19 of the developing sleeve cleaning member 18 moves in the direction of the arrow so that the developing sleeve cleaning member 18 comes into contact with the developing sleeve 7 and the developer carrying member. When the driving mechanism 1 (not shown) is turned on for a predetermined time and the developing sleeve 7 rotates, a frictional force is generated between the developing sleeve cleaning member 18 and the developing sleeve 7, and the fixed matter of the developing sleeve 7 is developed. The developing sleeve 7 is cleaned by moving to the sleeve cleaning member 18.

FIG. 3 is a schematic view showing the positional relationship between the developing sleeve extending in the longitudinal direction and the developing sleeve cleaning member as viewed from the left side of FIG. FIG. 4 is a schematic view showing the developing sleeve and the developing sleeve cleaning member as seen from the left side surface as in FIG. 3 showing the operation state of the developing sleeve cleaning member of FIG.
When the developing sleeve 7, the developing sleeve cleaning member 18, and the movable mechanism 19 of the developing sleeve cleaning member 18 shown in FIG. 3 reach a predetermined job end, the developing sleeve cleaning member 18 can be moved as shown in FIG. As the mechanism 19 moves from the broken line to the solid line portion, the developing sleeve cleaning member 18 comes into contact with the surface of the developing sleeve 7, and thereafter, the cleaning operation of the developing sleeve 7 (rotation of the developing sleeve 7) is performed.
When the developing sleeve 7 is cleaned, as a pre-processing operation for cleaning, the stirring mechanism 3 is stopped, only the developing sleeve 7 rotates for a predetermined time, and all the developer on the developing sleeve 7 falls into the developing casing and develops. The surface of the sleeve 7 is exposed. By performing the above operation, as shown in FIG. 2, all of the developer that was initially in the vicinity of the pumping pole 2 falls into the developing casing 20 at the developer cutting pole 4, so that the developer is around the pumping pole 2. As a result, there is no developer on the developing sleeve 7, and the developing sleeve 7 is exposed.

After the developing sleeve 7 is exposed, as described above, the developing sleeve cleaning member 18 is moved. When the developing sleeve 7 comes into contact with the developing sleeve 7, the developing sleeve 7 is rotated again for a predetermined time, thereby developing the developer. The developing sleeve 7 where the sticking occurs is cleaned.
More specifically, when the movable developing sleeve cleaning member 18 that covers the longitudinal direction of the developing sleeve 7 installed in the developing device 17 and contacts the surface of the developing sleeve 7 at the specified job end, again carries the developer. The drive mechanism of the body 1 is turned on for a predetermined time, and the surface of the developing sleeve 7 is periodically cleaned by the rotation of the developing sleeve 7, and the occurrence of sticking of the developing sleeve is suppressed, thereby preventing the occurrence of the above-mentioned problems.
A feature of the present invention is that when the developing sleeve 7 is cleaned, the developer is peeled off from the surface of the developing sleeve 7. If the developer remains on the surface of the developing sleeve 7 when the developing sleeve 7 is cleaned, the developing sleeve cleaning member 18 is damaged, leading to a decrease in service life and a decrease in cleaning efficiency.
Therefore, in the present invention, as described above, the driving of the agitating mechanism 3 is turned off and only the developing sleeve 7 is rotated, so that the developer is not pumped up, and the developer only drops from the developer carrier 1. By setting the state, the developer is surely removed from the surface of the developing sleeve 7. By executing this operation, the developing sleeve 7 is exposed on the surface without developer, and the life of the developing sleeve cleaning member 18 can be extended and the surface of the developing sleeve 7 can be efficiently cleaned.

FIG. 5 is a control block diagram for explaining the control of the two-component developing device according to the present invention.
In FIG. 5, a main body control device 30 of the image forming apparatus main body controls the control means 32 of the developing device 17 from a CPU provided on the main body side in response to an instruction from an operation unit 31 that instructs a series of image forming operations. In this embodiment, the CPU is provided on the main body side. The developing device 17 operates according to control information coming from the CPU on the main body side. However, the CPU may be provided in the developing device itself.
The control unit 32 of the developing device 17 performs control so that at least the stirring mechanism 3 is turned off and the developing sleeve 7 is kept on for a predetermined time at a job end specified by the main body control device 30 of the image forming apparatus main body. Thus, the developer is dropped into the developing casing 20 by the developer cutting pole 4 and the rotation of the developing sleeve 7 is temporarily stopped.
When the movable developing sleeve cleaning member 18 that covers the longitudinal direction of the developing sleeve 7 installed in the developing casing comes into contact with the surface of the developing sleeve 7, the developing sleeve 7 is turned on again for a predetermined time, and the developing sleeve 7 is rotated. To control. Reference numeral 33 denotes an image area ratio storing means to be described later.

FIG. 6 is a flowchart showing a series of developing sleeve cleaning operations.
2 and 6, first, the control means 32 of the developing device 17 connected to the control device 30 of the image forming apparatus main body described above is a job specified by the control device 30 of the image forming apparatus main body. At the end, it is determined whether or not the cleaning operation is performed (S1), and when there is no need for cleaning, the normal image forming mode is restored.
If it is determined that cleaning is necessary, the drive mechanism (not shown) of the stirring mechanism 3 is turned off (S2), and the drive mechanism (not shown) of the developing sleeve 7 is turned on for a predetermined time (T1) ( S3) In order to drop the developer on the developing sleeve 7 into the developing casing 20 and expose the surface of the developing sleeve 7 so that it can be smoothly cleaned by the developing sleeve cleaning member 18, the development of the developer carrying mechanism is once performed. The rotation of the sleeve 7 is stopped.

In the present embodiment, the (T1) value is set to 5 [seconds]. However, the (T1) value is a specification that can be changed (setting value of a device that can be changed by a serviceman or a user), process speed and development unit characteristics. To change. Further, the movable mechanism 19 of the developing sleeve cleaning member 18 is turned on (S4), and the surface of the developing sleeve 7 and the developing sleeve cleaning member 18 are brought into contact with each other (S5).
Then, again, the developing sleeve 7 is turned on for a predetermined time (T2) (S6), and a frictional force is generated between the developing sleeve 7 and the developing sleeve cleaning member 18, whereby the fixed matter on the surface of the developing sleeve 7 is It moves to the developing sleeve cleaning member 18 and the developing sleeve 7 is cleaned. In the present embodiment, the (T2) value is set to 60 [seconds]. However, like the (T1) value, the specification can be converted according to conditions.
As described above, in the present invention, at the job end of the two-component developing device, the driving of the stirring mechanism 3 is turned off, and the driving mechanism of the developing sleeve 7 that is a developer carrying member is kept on for a predetermined time. Since the developer is dropped into the developing casing 20 at the cutting pole 4 and the developer is temporarily removed from the developing sleeve 7 temporarily and the surface of the developing sleeve 7 is exposed, the life of the developing sleeve cleaning member 18 is increased. It is possible to improve the cleaning efficiency.

FIG. 7 is a sectional view showing a second embodiment of the two-component developing device according to the present invention applied to the printer of FIG. In FIG. 7, the basic configuration of the two-component developing device is the same as that of the first embodiment of FIG.
In FIG. 7, reference numeral 21 denotes a roller-shaped developing sleeve cleaning member that moves from the broken line to the solid line during the cleaning operation of the developing sleeve 7. At the time of cleaning, the roller-shaped developing sleeve cleaning member 21 is rotated in the reverse direction to the rotating direction of the developing sleeve 7 by a driving mechanism (not shown) in accordance with the rotating operation of the developing sleeve 7.
FIG. 8 is a schematic view showing a cross-sectional shape of the developing sleeve cleaning member of FIG. The developing sleeve cleaning member 21 includes an axial center 22 and a cleaning portion 23 that contacts and cleans the developing sleeve 7 during cleaning.
FIG. 9 is a graph showing the relationship between the developing sleeve cleaning time and the developing sleeve surface concentration in the first embodiment and the second embodiment. At the start of the experiment, the fixing of the developing sleeve is similarly promoted so that the surface density of the developing sleeve becomes the same. As the cleaning of the developing sleeve proceeds, the developing sleeve surface density decreases.

As a result of setting the horizontal axis as the cleaning time and the vertical axis as the developing sleeve surface concentration, the time until the developing sleeve surface concentration is reduced by about 3 times is the developing sleeve by the developing sleeve cleaning member of the first embodiment in FIG. The developing sleeve cleaning time by the developing sleeve cleaning member of the second embodiment in FIG. 7 is shorter than the cleaning time. That is, the developing sleeve cleaning time was shortened from about 60 [seconds] to about 30 [seconds], and the cleaning ability was doubled.
As shown in the second embodiment of FIG. 7, the developing sleeve cleaning member 21 is composed of the shaft 22 and the cleaning portion 23 covering the shaft 22, and during the cleaning, an operation reverse to the rotation direction of the developing sleeve 7 is executed. As a result, the cleaning capability of the developing sleeve 7 can be doubled, the cleaning time (T2) can be shortened, the developing sleeve 7 can be reliably cleaned, and the waiting time of the user can be shortened. Productivity can be improved.
Thus, when cleaning the developing sleeve 7, the roller-shaped cleaning member 21 rotates in the direction opposite to the developing sleeve 7, so that the frictional force between the developing sleeve cleaning member 21 and the developing sleeve 7 during cleaning increases. The cleaning ability of the developing sleeve 7 can be improved.

FIG. 10 is a graph showing the relationship between the developing sleeve cleaning time and the developing sleeve surface concentration in the first embodiment, the second embodiment, and the third embodiment. As a third embodiment, a melamine resin foam is used as the material of the cleaning portion 23 of the developing sleeve cleaning member 21 in FIG.
The melamine resin foam has excellent cleaning ability and can store foreign matters such as toner in the foamed layer. Therefore, the developing sleeve cleaning member 21 of the third embodiment using a melamine resin foam has a higher cleaning ability of the developing sleeve cleaning member 21 than the developing sleeve cleaning member 21 of the second embodiment.
By using the melamine resin foam as the cleaning portion 23 of the developing sleeve cleaning member 21 as in the third embodiment, the cleaning time (T2) can be further shortened, and the developing sleeve 7 is reliably cleaned. In addition, the waiting time of the user can be shortened, and productivity can be improved.

FIG. 11 is a sectional view showing a fourth embodiment of a developing sleeve cleaning member used in the two-component developing device. In FIG. 11, the developing sleeve cleaning member 24 includes a cored bar 25 and a brush-shaped cleaning unit 26.
The developing sleeve cleaning member 24 is made of an elastic material having a Young's modulus of 5000 MPa or less. The reason is that if the Young's modulus of the developing sleeve cleaning member 24 is too large, the frictional force when the developing sleeve cleaning member 24 and the developing sleeve come into contact with each other becomes small, and a cleaning effect is hardly obtained. Therefore, the developing sleeve cleaning member 24 is preferably made of an elastic material having a Young's modulus of 5000 MPa or less.

Elastic materials having a Young's modulus of 5000 MPa or less include natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene, styrene butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylonitrile butadiene rubber, ethylene-propylene rubber, neopropylene. Rubber materials such as rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicon rubber, fluorine rubber, urethane rubber, polyethylene elastomer, polyolefin elastomer, 1,2-polybutadiene elastomer, ethylene-acetic acid Vinyl elastomer, polyvinyl chloride elastomer, natural rubber elastomer, fluororubber elastomer, trans-polyisoprene elastomer, polyethylene chloride Thermoplastic elastomer materials such as lastmers, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polypropylene, polystyrene, polyamide, polyurethane, polycarbonate, polytetrafluoroethylene, acrylonitrile butadiene styrene resin, acrylotolyl butadiene styrene resin, methacrylic resin, Examples include synthetic resin materials such as melamine resin foam. Although various materials are listed, melamine resin foam is a preferable material among them.
By making the shape of the cleaning portion 26 of the developing sleeve cleaning member 24 into a brush shape, the stress on the cleaning portion 26 at the time of cleaning is dispersed, and the life of the developing sleeve cleaning member 24 can be increased. In the present embodiment, the brush material is used by coating a melamine resin foam around a metal wire.

FIG. 12 is a graph showing the lifetime of the cleaning portion of the developing sleeve cleaning member according to the third embodiment and the fourth embodiment. In the fourth embodiment, the brush material is a metal material wire coated with a melamine resin foam around the wire, but other materials may be used.
As described above, in the fourth embodiment, since the cleaning portion 26 of the developing sleeve cleaning member 24 has a brush shape, the frictional stress on the cleaning portion 26 during cleaning can be dispersed, and the life of the cleaning portion 26 is increased. it can.
FIG. 13 is a cross-sectional view showing a fifth embodiment of a developing sleeve cleaning member used in a two-component developing device. In FIG. 13, the basic configuration of the two-component developing device is the same as that of the first embodiment of FIG.
In the fifth embodiment of the developing sleeve cleaning member of FIG. 13, a small power pack 27 is provided. The small power pack 27 applies a bias having a polarity opposite to that of the toner component to the developing sleeve cleaning member 18. Since the toner component of the present embodiment has a negative polarity, a positive bias is applied during cleaning. By applying a positive bias at the time of cleaning as described above, the fixed matter on the developing sleeve 7 is electrostatically attracted to the developing sleeve cleaning member 18, and thus the cleaning ability is improved. Further, the developing sleeve cleaning member 18 of FIG. 13 is not in the form of a roller, but it is more effective to have a roller shape.

FIG. 14 is a graph showing the relationship between the developing sleeve cleaning time and the developing sleeve surface concentration according to the first embodiment, the second embodiment, the third embodiment, and the fifth embodiment. .
Since the polarity and the reverse bias of the toner component are applied to the developing sleeve cleaning member 18, the fixed matter on the developing sleeve 7 can be reliably recovered in a short time. As shown in FIG. 14, in the fifth embodiment, in addition to shortening the cleaning time, the developing sleeve surface concentration is further reduced, and fixed matters that cannot be removed by normal cleaning can be reliably cleaned.
The image density (ID), which is the image density measured by the measuring instrument, can be measured using a reflection type density measuring device (for example, product name X-Rite), and if this reflection type density measuring device is used, The developing sleeve surface concentration can also be measured.
The degree of promotion of developing sleeve fixing varies greatly depending on the output image area ratio. For example, when a solid image is always output, the fixing of the developing sleeve hardly promotes even if the number of printed sheets and the sleeve running time are large. On the contrary, when a blank paper image is always output, fixing of the developing sleeve is promoted even if the number of prints and the sleeve running time are small.
In the developing process from the developing sleeve 7 to the photosensitive drum 8 as an image carrier in FIG. 13, if the image area ratio is high, the toner in the pumped up developer is directed toward the photosensitive drum 8. Although it is attracted, when the image area ratio is low, the toner in the pumped up developer is attracted to the developing sleeve 7 side. At this time, fixing of the developing sleeve is greatly promoted.

FIG. 15 is a flowchart showing a series of developing sleeve cleaning operations of the two-component developing device of FIG. Referring to FIGS. 13 and 15, first, the control means 32 of the developing device 17 connected to the main body control device 30 of the image forming apparatus main body shown in FIG. 5 performs cleaning at the specified job end. The presence / absence of operation is determined (S11), and when there is no need for cleaning, the normal image forming mode is restored.
Here, the parameter of the total number of prints or the running time of the developing sleeve 7 and the non-image area ratio Σ (100−image area ratio) of the output image is used for the cleaning operation determination at the end of the job. This will be described as a sixth embodiment. A and B in FIG. 15 are specifications that can be changed according to the specifications of the developing device, developer characteristics, and the like.
When it is determined that cleaning is necessary, the drive mechanism (not shown) of the stirring mechanism 3 is turned off (S12), and the drive mechanism (not shown) of the developing sleeve 7 is turned on for a predetermined time (T1) ( S13) In order to drop the developer on the developing sleeve 7 into the developing casing 20 and expose the surface of the developing sleeve 7 so that it can be smoothly cleaned by the developing sleeve cleaning member 18, the developing sleeve of the developer carrying mechanism is temporarily used. 7 stops rotating.

In this embodiment, the (T1) value is set to 5 [seconds]. However, the (T1) value is changed depending on the process speed and the development unit characteristics as a changeable specification. Further, the movable mechanism 19 of the developing sleeve cleaning member 18 is turned on (S14), and the surface of the developing sleeve 7 and the developing sleeve cleaning member 18 are brought into contact with each other (S15).
Then, again, the developing sleeve 7 is turned on for a predetermined time (T2) (S16), and by generating a frictional force between the developing sleeve 7 and the developing sleeve cleaning member 18, the fixed matter on the surface of the developing sleeve 7 is It moves to the developing sleeve cleaning member 18 and the developing sleeve 7 is cleaned. In the present embodiment, the (T2) value is set to 60 [seconds]. However, like the (T1) value, the specification can be converted according to conditions.
As described above, in the present invention, at the job end of the two-component developing device, the driving of the stirring mechanism 3 is turned off, and the driving mechanism of the developing sleeve 7 that is a developer carrying member is kept on for a predetermined time. The developer is dropped into the developing casing 20 at the cutting pole 4 to temporarily and reliably remove the developer from the developing sleeve 7 so that the surface of the developing sleeve 7 is completely exposed. The service life can be improved and the cleaning efficiency can be improved.

The control device 30 of the main body of the image forming apparatus includes a function of storing the average of the image area ratio of the output image, and the value obtained by multiplying the non-image area ratio, which is 100−image area ratio, by the number of prints or the non-image area ratio. When the value obtained by multiplying the sleeve running time becomes a specified value, the developing sleeve cleaning member 18 performs a cleaning operation on the surface of the developing sleeve 7 constituting the developer carrier.
By adding a parameter of non-image area ratio (100-image area ratio) to the cleaning operation determination at the end of the job, it is possible to clean the surface of the developing sleeve 7 strictly in accordance with the promotion of fixing of the developing sleeve 7. Therefore, useless cleaning operation can be further suppressed, and unnecessary waiting time can be reduced, power consumption can be reduced, and the life of the developing sleeve cleaning member 18 can be increased.
The degree of promotion of developing sleeve fixing varies greatly depending on the output image area ratio. For example, in the case where a solid image is always output, the fixing of the developing sleeve hardly promotes even if the number of prints and the running time of the developing sleeve are large. On the contrary, when a blank paper image is always output, fixing of the developing sleeve is promoted even if the number of prints and the sleeve running time are small.
This is because, in the developing process from the developing sleeve 7 to the photosensitive drum 8, if the image area ratio is high, the toner in the pumped up developer is attracted in the direction of the photosensitive drum 8, but the image area ratio is high. When it is low, the toner in the developer drawn up is attracted to the developing sleeve 7 side. At this time, fixing of the developing sleeve is greatly promoted.

FIG. 16 is a graph showing the developing sleeve cleaning member and the cleaning of the developing sleeve surface at each job end by the operation in FIG. Regarding the life of the developing sleeve cleaning member 18, the image forming mode, which is the most frequently used condition in the market: 5 p / j, the image area ratio: 5%, when cleaning at the end of every job in an actual test of A4 landscape paper In comparison with FIG. 16, the effect of significantly increasing the life was obtained as shown in FIG.
FIG. 17 is a sectional view showing a seventh embodiment of a developing sleeve cleaning member used in the two-component developing device. FIG. 18 is a flowchart showing a series of developing sleeve cleaning operations of the two-component developing device of FIG. FIG. 19 is a graph showing the development sleeve cleaning member and the cleaning of the development sleeve surface at each job end by the operation in FIG.
In FIG. 17, the basic configuration of the two-component developing device is the same as the configuration of the first embodiment in FIG. 2.
In the seventh embodiment shown in FIG. 17, an optical sensor 28 for detecting the color density of the fixed matter on the developing sleeve 7 is provided. As shown in the flowchart of FIG. 18, the control means 32 connected to the main body control device 30 of the image forming apparatus main body turns off the drive mechanism (not shown) of the stirring mechanism 3 at every job end (S31). The drive mechanism (not shown) of the developing sleeve 7 is turned on for a predetermined time (T1) (S32), and the developing sleeve 7 of the developer carrying mechanism is temporarily rotated in order to perform the operation of exposing the developing sleeve 7. To stop.
Next, the optical sensor 28 detects the color density of the fixed matter on the developing sleeve 7.

Therefore, as shown in FIG. 18, it is determined whether or not the detected color density is higher than the threshold value (S33). If the color density is higher, cleaning of the surface of the developing sleeve 7 is executed. The cleaning operation is not executed and normal image formation is resumed.
In the present embodiment, when the optical sensor 28 is a P sensor used for toner replenishment control, the threshold C of the Vsp value is 1.00, and the threshold C is 1.00 or less, the surface of the developing sleeve 7 is dirty. And the surface of the developing sleeve 7 is cleaned. When the C value is larger than 1.00, the cleaning operation of the developing sleeve 7 is not performed, and the normal image formation is resumed.
Next, the movable mechanism 19 of the developing sleeve cleaning member 18 is turned on (S34), and the surface of the developing sleeve 7 and the developing sleeve cleaning member 18 are brought into contact with each other (S35). Again, the developing sleeve 7 is turned on for a predetermined time (T2) (S36).
In this embodiment, the C value threshold is set to 1.00, but the C value can also be changed (device setting value that can be changed by a serviceman or user) and matches the developing device specification and the developer. Change to a value. Further, although the P sensor is used as the optical sensor 28, other optical sensors such as a photo sensor may be used.

By providing a mechanism for determining whether or not the developing sleeve 7 can be cleaned as described above, it is possible to eliminate a wasteful cleaning operation in a state where the developing sleeve is not soiled and there is no fear of the sleeve fixing. In the actual machine test, the life of the developing sleeve cleaning member 18 was about doubled (about 20000 sheets → about 40000 sheets) as shown in FIG.
The optical sensor 28 detects the stain on the surface of the developing sleeve 7, and the developing sleeve cleaning member 18 is moved only when the developing sleeve 7 is promoted to be dirty, and when there is no acceleration, the developing sleeve cleaning member 18 is moved. Therefore, it is possible to eliminate a wasteful developing sleeve cleaning operation when there is no promotion of contamination of the developing sleeve 7, and it is possible to achieve unnecessary waiting time reduction, reduction of power consumption, long life of the developing sleeve cleaning member, and the like.
The fixing of the developing sleeve does not simply depend on the number of printed sheets, the sleeve running time, and the non-image area ratio, and is not easily promoted depending on the image forming conditions such as the developer (toner) physical properties, the system, and the paper passing environment. There are conditions.

For example, pulverized toner generally tends to adhere to the developing sleeve because the wax component of the toner is exposed on the surface of the mother body. However, the polymerized toner hardly adheres to the developing sleeve because the wax component penetrates into the mother body. Further, it is generally known that the higher the temperature in the developing device, the easier the fixing of the developing sleeve is promoted.
Therefore, after the surface of the developing sleeve 7 is exposed, the stain on the surface of the developing sleeve 7 is detected by the optical sensor 28, and the detection result exceeds a specified threshold value, that is, the fixing of the developing sleeve is promoted. Only, the developing sleeve cleaning member 18 moves in the longitudinal direction on the surface of the developing sleeve 7 to clean the surface of the developing sleeve 7.
As described above, only when the development sleeve fixing is promoted, the developing sleeve cleaning member 18 is made movable. When the development sleeve fixing is not promoted, the developing sleeve cleaning member 18 is not made movable so that the development sleeve fixing is prevented. By eliminating the useless cleaning operation of the developing sleeve 7 when there is no promotion, the life of the developing sleeve cleaning member 18 can be extended.

FIG. 20 is a sectional view showing an eighth embodiment of a developing sleeve cleaning member used in a two-component developing device. FIG. 21 is a flowchart showing a series of developing sleeve cleaning operations of the two-component developing device of FIG. FIG. 22 is a graph showing the developing sleeve cleaning member and the cleaning of the developing sleeve surface at each job end according to the operation in FIG.
In the eighth embodiment of the developing sleeve cleaning member shown in FIG. 20, the developing sleeve is stripped off at every job end, and is attached to the movable mechanism 19 of the developing sleeve surface cleaning member 18 so that the axis of the developing sleeve 7 is centered. A ground potential sensor 29 is provided.
In the eighth embodiment of the developing device, as shown in the flowchart of FIG. 21, the sleeve stripping operation for each job end, that is, the drive mechanism (not shown) of the stirring mechanism 3 is turned off for each job end ( In S41, the drive mechanism (not shown) of the developing sleeve 7 is turned on for a predetermined time (T1) (S42), and the developing sleeve 7 is exposed.
Next, a potential sensor 29 attached to the movable mechanism 19 of the sleeve surface cleaning member 18 and having the shaft center of the developing sleeve 7 as the ground is measured to determine whether the surface potential of the developing sleeve 7 is greater than the threshold value D. (S43).

If the threshold value D is 50 [−V] (absolute value) or more as a result of the measurement, it is determined that the promotion of developing sleeve fixation has started, and the developing sleeve 7 is cleaned to clean the surface of the developing sleeve 7. Run. If the D value is less than 50 [−V] (absolute value), it is determined that there is no concern of promoting sleeve fixation, and the developing sleeve cleaning operation is not performed, and the normal image formation is resumed.
In the present embodiment, the D value threshold is 50, but the D value is also changeable, and is changed to a value that matches the machine (developing device). Regarding the D value, in the developing sleeve 7 cleaning availability determination method described in the seventh embodiment, the cleaning operation of the developing sleeve 7 is carried out even when the toner has just adhered.
However, by using the potential sensor 29 that measures the surface potential on the developing sleeve 7 as a mechanism for determining whether or not the cleaning operation of the developing sleeve 7 is possible, it is possible to distinguish between the toner adhesion on the developing sleeve 7 and the fixing of the developing sleeve that is not a problem. Therefore, it becomes possible to eliminate a further unnecessary cleaning operation.
As a result, in the actual machine test of the sixth embodiment, the life of the developing sleeve cleaning member 18 is about 160000 sheets as shown in FIG. 22, and other PMs (parts to be replaced when the predetermined life is reached). It will be equal to or greater than the replacement parts.

As described above, the fixing of the developing sleeve is not simply dependent on the number of printed sheets, the sleeve running time, and the non-image area ratio, but is also promoted by image forming conditions such as developer (toner) physical properties, system, and paper passing environment. There are conditions that are easy and conditions that are not. In the above-described embodiment, the state where the developing sleeve is fixed is detected by the optical sensor 28 based on the density of the developing sleeve 7 due to the toner contamination, and it is determined whether the developing sleeve 7 can be cleaned.
However, the detection result of the optical sensor 28 cannot distinguish between the case where the toner has just adhered to the developing sleeve 7 and the state in which the fixing of the sleeve is promoted, and the toner has simply adhered to the developing sleeve 7. The developing sleeve cleaning member 18 is made movable even in a state where there is no problem. Originally, if the toner is simply adhered on the developing sleeve 7, no trouble occurs and no cleaning is required.

On the other hand, the residual potential on the developing sleeve 7 does not occur in a situation where the toner is only attached, but only when the developing sleeve is fixed. In this case, if the fixing of the developing sleeve is further promoted, a malfunction occurs, and thus the developing sleeve 7 needs to be cleaned.
Therefore, the residual potential on the surface of the developing sleeve 7 due to the fixing of the developing sleeve is measured by the potential sensor 29 installed in the vicinity of the developing sleeve 7, and the developing sleeve cleaning member 18 is moved only when the measurement result exceeds a specified threshold value. .
With this configuration, it is possible to eliminate the cleaning operation of the developing sleeve 7 when there is no promotion of fixing of the developing sleeve with higher accuracy, and it is possible to achieve a longer life of the developing sleeve cleaning member 18.
Serviceability and usability can be improved by using a developing device having a developing sleeve cleaning mechanism as a process cartridge integrated with a PCU (process cartridge unit) including a photosensitive unit.

  A Image forming apparatus, 1 developer carrying member (developing roller), 2 developer carrying mechanism (pumping electrode), 3 stirring mechanism, 4 developer carrying mechanism (developer cutting electrode), 5 developer carrying mechanism (main electrode) , 6 Developer carrying mechanism (magnet roller), 7 (developing sleeve), 8 image carrier (photosensitive drum), 9 layer thickness regulating member, 11 intermediate transfer belt, 12 image forming unit (process cartridge), 16 fixing unit , 17 Developing device, 18 Developing sleeve cleaning member, 19 Movable mechanism, 20 Developing casing, 21 Developing sleeve cleaning member, 24 Developing sleeve cleaning member, 27 Small power pack, 28 Developing sleeve cleaning member, 29 Potential sensor

Japanese Patent Laid-Open No. 10-312110 JP 2003-173086 A JP 2001-175078 A JP-A-6-59606

Claims (18)

An agitation mechanism for agitating a developer composed of toner and a magnetic carrier and supplying the developer near the developer carrying member;
Developing a developer formed by a magnet roller having a developer cutting pole that is a gap between adjacent magnets having the same polarity to which repulsive magnetic fields of a plurality of magnets arranged in a fixed manner are adjacent to each other, and a developing sleeve covering the periphery of the magnet roller The developer carrying member carried to a position;
A two-component developing device comprising: a control unit connected to a control device of the image forming apparatus main body;
Wherein, when the defined job end, and off the driving of at least the stirring mechanism, dropped developer by said developer cutting electrode by the developing sleeve continues to turn on a predetermined time in the developing casing, the developing When the developing sleeve cleaning member, which is movable and covers the longitudinal direction of the developing sleeve installed in the developing casing, comes into contact with the developing sleeve surface, the developing sleeve is turned on again for a predetermined time. The two-component developing device is controlled to rotate the developing sleeve. The developing sleeve cleaning member has an axial center and a cleaning portion that covers the axial center, and when the developing sleeve cleaning member contacts the surface of the developing sleeve, the developing sleeve cleaning member is in contact with the developing sleeve. 2. The two-component developing device according to claim 1, wherein the two-component developing device is reversely rotated. The two-component developing device according to claim 2, wherein the cleaning unit has a brush shape. 4. The two-component developing device according to claim 2, wherein the cleaning portion is a melamine resin foam. 5. The bias having a polarity opposite to that of the toner is applied to the shaft center of the developing sleeve cleaning member at a timing when the cleaning unit comes into contact with the developing sleeve. 2 component developing device. The control device of the image forming apparatus main body includes a function of storing an average of the image area ratio of the output image, and a value obtained by multiplying the non-image area ratio by the number of prints or the non-image area ratio is multiplied by a developing sleeve running time. 6. The two-component developing device according to claim 1, wherein a cleaning operation of the sleeve surface is executed when the specified value becomes a specified value. The developing sleeve surface exposed by dropping the developer into the developing casing is detected by an optical sensor, and when the detection result exceeds a predetermined threshold, the developing sleeve cleaning member cleans the developing sleeve surface. 6. The two-component developing device according to claim 1, wherein the two-component developing device is executed. When the residual potential on the surface of the developing sleeve exposed by dropping the developer into the developing casing is measured by a potential sensor installed at a position opposite to the surface of the developing sleeve, the residual potential exceeds a specified threshold value. The two-component developing device according to claim 1, wherein the developing sleeve cleaning member performs a cleaning operation on the surface of the developing sleeve . 9. A process cartridge comprising an image carrier and a developing device, wherein the developing device comprises the two-component developing device according to claim 1. The electrostatic latent image formed on the image carrier is visualized by developing with toner, the toner image is transferred onto a recording medium, and the toner image on the recording medium is fixed on the recording medium with heat and pressure. An image forming apparatus comprising the process cartridge according to claim 9 as a process cartridge including the image carrier. An agitation mechanism for agitating a developer composed of toner and a magnetic carrier and supplying the developer near the developer carrying member;
Developing a developer formed by a magnet roller having a developer cutting pole that is a gap between adjacent magnets having the same polarity to which repulsive magnetic fields of a plurality of magnets arranged in a fixed manner are adjacent to each other, and a developing sleeve covering the periphery of the magnet roller The developer carrying member carried to a position;
An image forming apparatus including a two-component developing device including a control unit connected to a control device of the image forming apparatus main body;
The control device of the main body of the image forming apparatus turns off the stirring mechanism at least at a specified job end and keeps the developing sleeve on for a predetermined time, thereby developing the developer at the developer cutting pole. down within the rotation of the developing sleeve is stopped, when the developing sleeve cleaning member is movable to cover the longitudinal direction of the developing sleeve installed in the developing casing is in contact on the surface of the developing sleeve, again, the developing the sleeve and the predetermined time on, the image forming apparatus and controls to rotate the developing sleeve. The developing sleeve cleaning member has an axial center and a cleaning portion that covers the axial center, and when the developing sleeve cleaning member contacts the surface of the developing sleeve, the developing sleeve cleaning member is in contact with the developing sleeve. The image forming apparatus according to claim 11, wherein the image forming apparatus rotates reversely. The image forming apparatus according to claim 11, wherein the cleaning unit has a brush shape. The image forming apparatus according to claim 12, wherein the cleaning unit is a melamine resin foam. The bias having a polarity opposite to that of the toner is applied to the shaft center of the developing sleeve cleaning member at a timing when the cleaning unit comes into contact with the developing sleeve. Image forming apparatus. The control device of the image forming apparatus main body includes a function of storing an average of the image area ratio of the output image, and a value obtained by multiplying the non-image area ratio by the number of prints, or the non-image area ratio, and a developing sleeve running time. 16. The image forming apparatus according to claim 11, wherein a cleaning operation of the surface of the developing sleeve is executed when the multiplied value becomes a specified value. The developing sleeve surface exposed by dropping the developer into the developing casing is detected by an optical sensor, and when the detection result exceeds a predetermined threshold, the developing sleeve cleaning member cleans the developing sleeve surface. The image forming apparatus according to claim 11, wherein the image forming apparatus is executed. When the residual potential on the surface of the developing sleeve exposed by dropping the developer into the developing casing is measured by a potential sensor installed at a position opposite to the surface of the developing sleeve, the residual potential exceeds a specified threshold value. The image forming apparatus according to claim 11, wherein the developing sleeve cleaning member performs a cleaning operation on the surface of the developing sleeve .

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