JP2016109746A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of maintaining sufficient lubrication properties between a cleaning member and a conveyance body, even in a situation where toner is easily deteriorated in a cartridge including a developing unit.SOLUTION: An image forming apparatus 100 having a plurality of image forming part I and a cleaning member 21 comprises: detection means for detecting an index value correlating with a deterioration state of toner stored in a developing unit 30 for each of the plurality of image forming parts I; and control means 26 for making a cleaning part 30 execute a supply operation of supplying toner of a toner image for supply. When there are an image formation part I whose index value exceeds a predetermined threshold in a direction where a degree of deterioration of the toner is large and an image forming part I whose index value does not exceed the threshold, the control means 26 performs control to make the toner amount of a toner image for supply transferred from the image forming part I whose index value exceeds the threshold less than the toner amount of a toner image for supply transferred from the image forming part I whose index value does not exceed the threshold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, or a facsimile apparatus using an electrophotographic system or an electrostatic recording system.

  2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic method has a plurality of image forming portions that form images of different colors, and images formed by the plurality of image forming portions are on an intermediate transfer member or a recording material carrier. In some cases, a color image is formed by superimposing and transferring on a recording material carried on the recording medium. A method using an intermediate transfer member is called an intermediate transfer method, and a method using a recording material carrier is called a direct transfer method. Intermediate transfer belts and recording material carrier belts, which are composed of endless belts, are widely used as a carrier for carrying and conveying a toner image directly or via a recording material, which is used as an intermediate transfer member or a recording material carrier. It is used. Further, each image forming unit includes a developing device that supplies toner to the image carrier and forms a toner image, and is a cartridge that can be attached to and detached from the image forming apparatus main body together with the image carrier. There is something.

  Since the toner adheres to the transport body by an image output operation or an adjustment operation of the image forming apparatus, cleaning for removing and collecting the toner is performed. As a cleaning method for the transport body, there is a blade cleaning system in which a cleaning blade, which is a plate-like cleaning member formed of rubber or the like, is brought into contact with the transport body, and the toner is scraped off from the moving transport body by the cleaning blade. Widely adopted.

  In the blade cleaning method, when an excessive frictional force acts between the cleaning blade and the conveyance body, there is a problem in that the tip of the cleaning blade is turned over or defective.

  Therefore, as disclosed in Patent Document 1, toner as a lubricant is periodically supplied to the cleaning unit in which the cleaning blade contacts the conveyance body, and the lubricity between the cleaning blade and the conveyance body is maintained. There is a way.

  On the other hand, in recent years, due to demands for improving usability and reducing running costs, the life of cartridges has been extended, and toner deterioration has become more prominent in the second half of the life of cartridges.

JP 2009-205109 A

  In the method of Patent Document 1, it is attempted to suppress consumption of undegraded toner by selectively supplying deteriorated toner to the cleaning blade unit.

  However, according to the study by the present inventors, for example, in the latter half of the life of the cartridge having a long life as described above, the deteriorated toner does not function as a lubricant, and the tip of the cleaning blade is turned over or the cleaning is poor. It became clear that occurred.

  Accordingly, an object of the present invention is to maintain sufficient lubricity between the cleaning member and the conveyance body even in a situation where the toner is likely to be deteriorated by extending the life of the cartridge including the developing device. An image forming apparatus is provided.

  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention provides an image carrier that carries a toner image, and a plurality of image forming units each having a developer that contains the toner and supplies the toner to the image carrier to form a toner image. A conveyance body for conveying a toner image transferred from the image carrier of the plurality of image forming units or a recording material on which a toner image is transferred from the image carrier of the plurality of image forming units; A detecting unit that detects an index value correlated with a deterioration state of the toner stored in the developing unit for each of the plurality of image forming units. A supply operation for supplying toner to the cleaning unit, wherein a transfer toner image is transferred from at least one image forming unit of the plurality of image forming units to the conveyance unit, and the conveyance unit And a control unit configured to perform a supply operation of transporting and supplying the toner of the supply toner image to the cleaning unit, wherein the control unit includes the index value of the plurality of image forming units. When there is an image forming unit that exceeds a predetermined threshold and an image forming unit that does not exceed a predetermined threshold in a direction in which the degree of deterioration is large, the index value is the index value of the image forming unit that transfers the supply toner image to the transport body. The amount of toner in the supply toner image transferred from the image forming unit exceeding the threshold value to the conveyance body is transferred to the conveyance body from the image formation unit whose index value does not exceed the threshold value. The supply toner is supplied to the transport body only from at least one image forming unit in which the index value does not exceed the threshold among the plurality of image forming units. An image forming apparatus and controls so as to transfer the image.

  According to another aspect of the present invention, a control unit that executes a supply operation includes: an image forming unit having the first index value among the plurality of image forming units; and an index value having the first value. The toner image for transfer is transferred from the image forming unit having the second value indicating that the degree of deterioration of the toner is larger than the case to the conveyance body, and the index value is transferred from the image forming unit having the second value. Control the toner amount of the supply toner image transferred to the transport body to be smaller than the toner amount of the supply toner image transferred to the transport body from the image forming portion whose index value is the first value. An image forming apparatus is provided.

  According to the present invention, sufficient lubricity between the cleaning member and the conveyance body can be maintained even in a situation where the toner including the developing device has a long life and the toner is likely to deteriorate.

1 is a schematic cross-sectional view of an image forming apparatus. FIG. 3 is a schematic cross-sectional view of a developing device. FIG. 6 is a flowchart illustrating a basic operation procedure in a toner supply mode. FIG. 3 is a flowchart of a toner supply mode according to the first exemplary embodiment. FIG. 10 is a flowchart of a toner supply mode according to a second exemplary embodiment. FIG. 10 is a flowchart illustrating a toner supply mode according to a third exemplary embodiment. FIG. 6 is a schematic cross-sectional view of another example of an image forming apparatus.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

[Example 1]
1. FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 according to the present exemplary embodiment is a tandem type laser beam printer that employs an intermediate transfer method that can form a full color image by an electrophotographic method.

  The image forming apparatus 100 includes first, second, third, and fourth image forming units IY, IM, IC, and IK as a plurality of image forming units (stations) S. In each of the image forming units IY, IM, IC, and IK, process cartridges (cartridges) PY, PM, PC, and PK that are detachable from the apparatus main body 110 of the image forming apparatus 100 are mounted. In the present embodiment, the configuration and operation of the four image forming units IY, IM, IC, and IK are substantially the same except that the color of the toner used is different. In this embodiment, the four cartridges PY, PM, PC, and PK have substantially the same structure, and the colors of the contained toner are yellow (Y), magenta (M), and magenta, respectively. The difference is cyan (C) and black (K). Therefore, hereinafter, unless it is particularly necessary to distinguish between the first, second, third, and fourth image forming units IY, IM, IC, and IK, the end of the code indicating that the element is provided. The elements Y, M, C, and K are omitted, and the elements will be described collectively. In addition, when distinguishing elements provided for the first, second, third, and fourth image forming units IY, IM, IC, and IK, “yellow”, “magenta”, “cyan”, “ Sometimes described with “black”.

  The cartridge P has a photosensitive drum 1 which is a drum-type (cylindrical) electrophotographic photosensitive member (photosensitive member) as an image carrier. The cartridge P includes a charging roller 2 as a charging unit, a developing roller 3 as a developing unit, and a drum cleaning blade 4 as a photosensitive member cleaning unit as process units that act on the photosensitive drum 1. Further, the cartridge P includes a toner container 23 and a waste toner container 24. In the image forming unit I, a laser unit (laser scanner) 7 as an exposure unit is disposed below the cartridge P.

  The photosensitive drum 1 is rotationally driven in the direction of arrow R1 in the figure. The surface of the rotating photosensitive drum 1 is applied with a predetermined negative polarity charging voltage (charging bias) from a charging power source (not shown) as a charging voltage application unit to the charging roller 2, thereby having a predetermined negative polarity. It is charged uniformly to the potential. The surface of the charged photosensitive drum 1 is exposed based on the image signal by the laser unit 7, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is developed by the developing roller 3 using toner as a developer contained in the toner container 23 to form a toner image on the photosensitive drum 1. At this time, a predetermined negative development voltage (development bias) is applied to the development roller 3 from a development power supply (not shown) as a development voltage application unit. In this embodiment, the exposed portion on the photosensitive drum 1 where the absolute value of the potential has been reduced after being uniformly charged is exposed to the same polarity as the charging polarity (negative polarity in this embodiment) of the photosensitive drum 1. Charged toner adheres (reverse development).

  An intermediate transfer belt 8 composed of an endless belt as an intermediate transfer member is disposed so as to face the photosensitive drums 1Y, 1M, 1C, and 1K of the image forming units IY, IM, IC, and IK. . The intermediate transfer belt 8 is an example of a conveyance body that conveys the toner images transferred from the image carriers of the plurality of image forming units. The intermediate transfer belt 8 is supported by a driving roller 9 and a driven roller 10 as a plurality of supporting rollers. The intermediate transfer belt 8 is rotated (circulated) in the direction of the arrow R2 in the drawing when the driving force is transmitted by the driving roller 9 being rotated. On the inner peripheral surface side of the intermediate transfer belt 8, primary transfer rollers 6Y, 6M, 6C, and 6K as primary transfer units are disposed to face the photosensitive drums 1Y, 1M, 1C, and 1K. The primary transfer roller 6 is pressed toward the photosensitive drum 1, contacts the photosensitive drum 1 via the intermediate transfer belt 8, and a primary transfer portion (primary transfer nip) T1 where the intermediate transfer belt 8 and the photosensitive drum 1 are in contact with each other. Form.

  The primary transfer roller 6 is supplied with a primary transfer voltage (positive polarity) having a polarity opposite to the charging polarity (normal charging polarity) of toner during development from a primary transfer power source (not shown) as a primary transfer voltage application unit. Primary transfer bias) is applied. As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 8 in the primary transfer portion T1. For example, when forming a full-color image, the primary transfer is performed so that the toner images on the photosensitive drums 1Y, 1M, 1C, and 1K of the image forming units IY, IM, IC, and IK are sequentially superimposed on the intermediate transfer belt 8. Is done. As a result, a multi-toner image in which the four color toner images are superimposed on the intermediate transfer belt 8 is formed.

  On the outer peripheral surface side of the intermediate transfer belt 8, a secondary transfer roller 11 as a secondary transfer unit is disposed to face a driving roller 9 that also serves as a counter roller. The secondary transfer roller 11 is pressed toward the drive roller 9, contacts the drive roller 9 via the intermediate transfer belt 8, and a secondary transfer portion (secondary transfer portion) where the intermediate transfer belt 8 and the secondary transfer roller 11 are in contact with each other. (Next transfer nip) T2 is formed. A recording material S such as a recording sheet or a plastic sheet is supplied to the secondary transfer portion T2. That is, the feeding / conveying device 12 includes a cassette 13 that stores the recording material S, a feeding roller 14 that feeds the recording material S from the cassette 13, and a transport roller pair 15 that transports the fed recording material S. Then, the recording material S conveyed from the paper feeding / conveying device 12 is conveyed to the secondary transfer portion T2 by the registration roller pair 16 in synchronization with the toner image on the intermediate transfer belt 8.

  A secondary transfer voltage (secondary transfer bias) is applied to the secondary transfer roller 11 from a secondary transfer power source (not shown) as a secondary transfer voltage application unit, which has a polarity opposite to the normal charging polarity of the toner. ) Is applied. As a result, the toner image on the intermediate transfer belt 8 is transferred (secondary transfer) to the recording material S being nipped and conveyed between the intermediate transfer belt 8 and the secondary transfer roller 11 in the secondary transfer portion T2. The

  The recording material S to which the toner image has been transferred is conveyed to a fixing device 17 as a fixing unit, and is heated and pressed by a fixing film 17a and a pressure roller 17b, and the toner image is fixed (fixed) on the surface. The The recording material S on which the toner image is fixed is discharged to the outside of the apparatus main body 110 by the discharge roller pair 18.

  The toner (primary transfer residual toner) remaining on the surface of the photosensitive drum 1 after the primary transfer process is removed from the surface of the photosensitive drum 1 by the drum cleaning blade 4 and collected in the waste toner container 24. Further, on the outer peripheral surface side of the intermediate transfer belt 8, a belt cleaning blade 21 as an intermediate transfer member cleaning unit is disposed so as to face the driven roller 10. The toner remaining on the surface of the intermediate transfer belt 8 after the secondary transfer process (secondary transfer residual toner) is removed from the surface of the intermediate transfer belt 8 by the belt cleaning blade 21 and collected in a waste toner container 22.

  The image forming apparatus 100 includes a color misregistration detection sensor 27 that is an optical sensor that detects a calibration toner pattern formed on the intermediate transfer belt 8. The color misregistration detection sensor 27 is disposed to face the driving roller 9 with the intermediate transfer belt 8 interposed therebetween. The image forming apparatus 100 also irradiates the recording material S sandwiched between the registration roller pair 16 with light, and determines the type of the recording material S based on the result of imaging the recording material S. Is provided.

  In this embodiment, the cartridge P, the laser unit 7 and the primary transfer roller 6 constitute an image forming unit I. Further, a developing device 30 is constituted by the developing roller 3, the toner container 23, and the like. The drum cleaning blade 40, the waste toner container 24, and the like constitute a drum cleaning device 40. Further, the belt cleaning device 20 is configured by the belt cleaning blade 21, the waste toner container 22, and the like.

  Here, FIG. 2 is a schematic cross-sectional view of the developing device 30 in the present embodiment. As described above, the developing device 30 includes the rotatable developing roller 3 as a developer carrying member constituting the developing unit, and the toner container 23 for containing toner as a developer containing portion. Further, the developing device 30 is provided with a developing blade 31 as a developer regulating means in contact with the developing roller 3. Further, the developing device 30 is provided with a stirring member (stirring blade) 32 that stirs the toner and conveys the toner toward the developing roller 3 inside the toner container 23. The toner conveyed to the vicinity of the developing roller 3 by the stirring member 32 is supplied onto the rotating developing roller 3, and after the layer thickness is regulated at the contact portion (nip) between the developing blade 31 and the developing roller 3, the photosensitive member The drum 1 and the developing roller 3 are conveyed to a facing portion (developing portion).

  Further, the image forming apparatus 100 is provided with a control board (control unit) 25 on which an electric circuit for controlling the image forming apparatus 100 is mounted. The control board 25 is provided with a CPU 26 as a control unit. It has been. The CPU 26 controls the drive source (not shown) related to the conveyance of the recording material S, the drive source (not shown) of the intermediate transfer belt 8 and the cartridge P, the control related to image formation, and the control related to failure detection. For example, the operations of the image forming apparatus 100 are collectively controlled.

  In the present embodiment, the cartridge P is provided with a memory 50 (FIG. 2) as a storage means. As will be described later, the memory 50 stores the remaining number detection means for detecting the remaining amount of toner and the number of rotations of the developing roller 3 as detection means for detecting an index value correlated with the deterioration state (degradation degree) of the toner. The detection result of the rotation speed detection means to be detected is stored.

2. Toner In this embodiment, a non-magnetic one-component developer (non-magnetic toner) is used as the developer. The toner used in this embodiment has a substantially spherical shape with a particle size of 5 to 8 μm. In the image forming apparatus 100 of this embodiment, since the transfer is performed twice in total, that is, the primary transfer and the secondary transfer, a spherical toner having a good transfer property is used. This toner is manufactured by a polymerization method, and becomes substantially spherical due to the manufacturing method. The toner includes an ester wax in a core, and has a styrene-butyl acrylate layer and an outermost styrene-polyester layer as a resin layer thereon. In addition, an external additive is added to stabilize the charged performance and impart lubricity. Therefore, the lubricity of the toner is mainly borne by this external additive, and plays an important role in a toner supply mode (supply operation) described later.

  In this embodiment, a spherical toner having a small particle diameter with high resolution and good transfer property is manufactured by a polymerization method. However, the present invention is not limited to this. For example, a toner prepared by a mechanical pulverization classification method, or a toner that has been subjected to thermal or mechanical post-treatment to form a spherical toner may be used. The toner may be a magnetic toner. Further, the developer may be a two-component developer in which toner and carrier are mainly mixed.

3. Execution Timing of Toner Supply Mode A belt cleaning blade (hereinafter also simply referred to as “cleaning blade”) 21 is a blade-like cleaning unit for removing residual toner on the intermediate transfer belt 8. In this embodiment, the cleaning blade 21 is made of urethane rubber (elastic rubber member) as an elastic member. The cleaning blade 21 has a predetermined length in each of a longitudinal direction arranged along a direction (width direction and thrust direction) substantially perpendicular to the moving direction of the intermediate transfer belt 8 and a short direction perpendicular to the longitudinal direction. And a plate-like member having a predetermined thickness. The cleaning blade 21 is counter-directional with an applied pressure of about 0.49 N / cm with respect to the intermediate transfer belt 8 at the edge portion on the intermediate transfer belt 7 side of one end portion (free end portion) in the short direction. Is in pressure contact. In other words, the cleaning blade 21 is arranged such that the free end portion is arranged upstream of the moving direction of the intermediate transfer belt 8 relative to the fixed end portion in the short direction, and the free end portion faces the upstream side of the moving direction. The intermediate transfer belt 8 is in contact therewith. In this embodiment, the cleaning blade 21 is pressed against the driven roller 10 via the intermediate transfer belt 8. A contact portion between the cleaning blade 21 and the intermediate transfer belt 8 is a cleaning portion (cleaning nip) N.

  In general, a large frictional force is generated between the cleaning blade 21 and the intermediate transfer belt 8. If the frictional force is too large, the cleaning blade 21 is distorted. As a result, there is a gap between the cleaning blade 21 and the intermediate transfer belt 8, and toner may slip through the cleaning blade 21 and the cleaning performance may not be satisfied. In some cases, the tip of the cleaning blade 21 that is brought into contact with the intermediate transfer belt 8 in the counter direction may be turned up.

  In order to suppress this phenomenon, a powdery lubricant is applied to the edge portion of the cleaning blade 21, and then the cleaning blade 21 and the intermediate transfer belt 8 are brought into pressure contact with each other so as to reduce the frictional force. Sometimes. However, when the image output operation is repeated, the amount of lubricant gradually decreases. Therefore, in order to maintain the cleaning performance continuously, it is desirable to periodically supply the lubricant to the cleaning portion N between the cleaning blade 21 and the intermediate transfer belt 8. In this embodiment, the toner (more specifically, the external additive) plays a role as a lubricant. That is, in this embodiment, a toner supply mode (supply operation) for supplying toner to the cleaning unit N periodically is executed at a predetermined timing. Hereinafter, the toner supplied to the cleaning unit N in this toner supply mode is referred to as “auxiliary toner” because it is a toner that assists cleaning for convenience. However, the auxiliary toner itself is no different from the toner used for normal image formation.

  In this embodiment, the toner supply mode is executed by the CPU 26 at the time of non-image formation at a preset frequency according to the number of rotations of the intermediate transfer belt 8. Table 1 shows an example of the execution timing of the toner supply mode in this embodiment.

  Here, the image forming apparatus 100 performs a series of image forming operations (jobs) that form and output an image on a single or a plurality of recording materials S, which is started by one start instruction. A job generally includes an image forming process (printing process), a pre-rotating process, a paper-to-paper (inter-recording-material) process when images are formed on a plurality of recording materials S, and a post-rotating process. The image forming process is a period in which an electrostatic latent image of an image that is actually formed and output on the recording material S, a toner image, a primary transfer or a secondary transfer of the toner image is performed. This is the period. The pre-rotation process is a period for performing a preparatory operation before the image forming process from when the start instruction is input until the actual image formation is started. The inter-sheet process is a period corresponding to the interval between the recording material S and the recording material S when the image forming process is continuously performed on the plurality of recording materials S (continuous image formation). The post-rotation process is a period during which an organizing operation (preparation operation) after the image forming process is performed. The non-image forming period is a period other than the image forming time, and is a preparatory operation at the time of turning on the power of the image forming apparatus 100 or returning from the sleep state. This is included during the previous multi-rotation process.

  As shown in Table 1, for example, during continuous printing, the CPU 26 temporarily interrupts job image formation for every 200 prints, extends the inter-sheet process, and executes the toner supply mode. Also, the four-sheet intermittent printing shown in Table 1 is an operation of repeatedly entering a standby state after performing a job with four image forming sheets and then performing a job with four image forming sheets. In this case, every time the number of printed sheets reaches 122, the CPU 26 causes the toner supply mode to be executed in the inter-sheet process as described above. The same applies to two-sheet intermittent printing and one-sheet intermittent printing. Intermittent printing has a higher frequency of executing the toner supply mode than continuous printing, and intermittent printing has a higher frequency of executing the toner supply mode as the number of job images formed is smaller. This is because in intermittent printing, the pre-rotation process and the post-rotation are performed for each job, so that the lubricant in the cleaning portion N is likely to be reduced with a smaller number of image formations. The toner supply mode is not limited to being executed in the inter-sheet process, and can be executed during non-image formation. For example, when a predetermined number of image formations as shown in Table 1 is reached, the toner supply mode is executed in the post-rotation process after the end of image formation of the job or the pre-rotation process of the next job. May be.

4). Deterioration of toner As the amount of repeated use (use time, drive time) of the cartridge P increases, the toner is lubricated by releasing the external additive or burying the external additive in the toner base. Will be lost. Here, for convenience, this phenomenon is called “deterioration” of the toner. There are two factors that cause the toner to deteriorate depending on the printing conditions.

  First, when there are many prints of a high printing rate with a large amount of toner consumption, the remaining amount of toner is the dominant factor and the toner deteriorates. When the remaining amount of toner decreases, the gap in the toner container 23 increases as compared to when the remaining amount of toner is large. As a result, the moving distance of the toner stirred with a predetermined stirring force within the toner container 24 increases. As the toner movement distance increases, the number of times of passing through various rubbing locations represented by the nip formed by the developing roller 3 and the developing blade 31 increases, so that the toner is likely to deteriorate.

  On the other hand, particularly when there are many prints with low toner consumption and low printing rate, although the toner consumption is small, the rotation time of the development roller 3 increases, so the rotation speed (or rotation time) of the development roller 3 is increased. Becomes a dominant factor, and the toner deteriorates. As the developing roller 3 rotates, the toner is damaged and deteriorated due to physical contact at various rubbing locations represented by a nip formed by the developing roller 3 and the developing blade 31. Further, as the amount of repetitive use of the cartridge P increases (that is, as the operation time of the driving means of the developing device 30 increases), the deterioration of the toner is further reduced due to the deterioration and contamination of the surface property of the developing roller 3 and the developing blade 31 itself. It becomes easy to promote.

  As described above, the deteriorated toner loses its lubricity due to free or embedded external additives. Therefore, the deteriorated toner has a smaller specific surface area because the amount of the external additive on the surface is smaller than that of the new toner. Therefore, by measuring and comparing the specific surface area (BET value) of the toner before and after repeated use of the cartridge P, the deterioration state (deterioration degree) of the toner can be evaluated. Here, the BET value of the toner after repeated use of the cartridge P with respect to the BTE value of the toner before repeated use of the cartridge P is expressed as a percentage, and is used as an index for evaluating the deterioration state of the toner. According to the study by the present inventors, it has been found that the above index of the deteriorated toner is less than 80%. For the measurement of the BET value, for example, a specific surface area measurement device “Gemini 2375 Ver. 5.0” (manufactured by Shimadzu Corporation) can be used.

5. Basic Operation in Toner Supply Mode Next, the basic operation in the toner supply mode will be described with reference to FIG. FIG. 3 is a flowchart illustrating a basic operation procedure in the toner supply mode. Here, it is assumed that auxiliary toner is supplied to the cleaning unit N from all cartridges P mounted on the image forming apparatus 100.

  When the execution timing of the toner supply mode comes, the CPU 26 rotates the photosensitive drum 1 and the intermediate transfer belt 8 of each image forming unit I (S101), and shifts to an image formation standby state (S102). Then, the CPU 26 forms a supply toner image, which is a predetermined toner image for supplying auxiliary toner to the cleaning unit N, on the photosensitive drum 1 of each image forming unit I, and the supply toner image is transferred to the intermediate transfer belt 8. (S103). Note that the operation itself for forming the supply toner image and transferring it to the intermediate transfer belt 8 is the same as the operation for forming the image to be transferred to the recording material S and output. That is, the uniformly charged photosensitive drum 1 is exposed for a predetermined time by the laser unit 7 to form an electrostatic latent image, and the electrostatic latent image is developed with toner to form a toner image. Is transferred to the intermediate transfer belt 8. The supply toner image formed at this time is set so that sufficient auxiliary toner can be supplied to the cleaning unit N. Here, predetermined lengths are respectively provided in the main scanning direction (direction substantially perpendicular to the moving direction of the surface of the photosensitive drum 1 and the intermediate transfer belt 8) and in the sub-scanning direction (moving direction of the surface of the photosensitive drum 1 and the intermediate transfer belt 8). A solid band image that is a solid band image (image of the highest density level) having a thickness.

  Next, the CPU 26 allows the supply toner image on the intermediate transfer belt 8 to pass through the secondary transfer portion T2 (S104) and causes the auxiliary toner to reach the cleaning portion N (S105). The supply toner image is obtained by separating the secondary transfer roller 11 from the intermediate transfer belt 8 or applying a negative secondary transfer voltage having the same polarity as the toner charging polarity to the secondary transfer roller 11. It can pass through the secondary transfer portion T2 to reach the cleaning portion N.

  With the above operation, auxiliary toner as a lubricant can be supplied from each image forming unit I to the cleaning unit N.

  Here, as described above, in the method of Patent Document 1, deteriorated toner is selectively supplied as a lubricant to the cleaning unit. In this case, since the lubricity of the deteriorated toner is lost, the auxiliary toner supplied to the cleaning unit in the toner supply mode may not function as a lubricant. As a result, the tip of the cleaning blade may be turned over or a cleaning failure may occur. Specifically, according to the study by the present inventors, when a durability test by intermittent printing of two sheets at a low printing rate of 1% is performed, a defective cleaning occurs after passing 30,000 sheets at the end of the cartridge life. did.

  Therefore, in this embodiment, when the toner supply mode is executed, the deterioration state of the toner stored in the cartridge P of each image forming unit I is determined. Then, the amount of auxiliary toner supplied from the cartridge P determined to have deteriorated to the cleaning unit N is made smaller than the amount of auxiliary toner supplied from the other cartridges P to the cleaning unit N. Thereby, sufficient lubricity between the cleaning blade 21 and the intermediate transfer belt 8 in the cleaning unit N is maintained, and turning-up of the tip of the cleaning blade 21 and poor cleaning are suppressed. This will be described in detail below.

6). Determination Method of Toner Degradation State Next, a determination method of the toner deterioration state will be described. As described above, the deterioration of the toner can be determined from the remaining amount of toner and the number of rotations of the developing roller 3. For this reason, in this embodiment, the remaining life value of the developing device 3 determined from the remaining amount of toner and the number of rotations of the developing roller 3 is used as an index value that correlates with the deteriorated state of the toner to determine the deteriorated state of the toner. There is a possibility that the degree of deterioration of the toner stored in the toner container 23 is larger in the case of the second value that is smaller than the first value than in the case of the first value. Indicates.

  In this embodiment, each cartridge P is provided with a memory 50 as storage means for storing information relating to the remaining amount of toner and information relating to the number of rotations of the developing roller 3. In this embodiment, the memory 50 is attached to the developing device 30. The memory 50 is a non-volatile memory that can be read and written. Each memory 50 is electrically connected to the control board 25 by a connector in a state where each cartridge P is mounted on the apparatus main body 110, and information can be exchanged with the CPU 26. That is, the information in each memory 50 can be read and written by the CPU 26.

  The storage means may be a non-contact memory that can be read and written, such as an electromagnetic coupling method that can transmit and receive signals in a non-contact state. In the present embodiment, as described above, the information about the index value correlated with the toner deterioration state is stored in the storage unit that is attached to the cartridge P and is removable from the apparatus main body 110 together with the developing device 30. As a result, when the cartridge P is removed from the apparatus main body 110 before reaching the end of its life and used in exchange for another cartridge P, the above information is attached to each developing device 30 itself. Control according to each developing device 30 is always possible. However, the present invention is not limited to this, and information regarding the index value correlated with the toner deterioration state is stored in association with each developing device 30 in the storage unit provided in the apparatus main body 110. It may be.

  First, an index value of the deterioration state of the toner obtained based on the remaining amount of toner will be described. In this embodiment, the remaining amount of toner stored in the toner container 23 is detected by a remaining amount detecting mechanism 5 as remaining amount detecting means using an optical detection method, as shown in FIG. In this embodiment, around the toner container 23 constituting the developing device 30, a light emitting unit 51 having a light emitting element that emits light, a light receiving unit 52 having a light receiving element that receives the light (detection light), Is arranged. Further, remaining amount detection windows 53 and 54 that are translucent windows are provided on the optical path of the toner container 23 so that the detection light passes through a predetermined portion of the toner container 23. Thus, a light detection circuit from the light emitting unit 51 to the light receiving unit 52 through the toner container 23 is configured. Further, a mylar sheet 55 as a wiping member for cleaning the remaining amount detection windows 53 and 54 is attached to the tip of the stirring member 32, and the remaining amount detection windows 53 and 54 are synchronized with the rotation of the stirring member 32. The inner surface side of the toner container 23 is wiped off. The light emitting unit 51, the light receiving unit 52, the remaining amount detecting windows 53 and 54, the mylar sheet 55, and the like constitute the remaining amount detecting mechanism 5.

  The remaining amount detection mechanism 5 detects the remaining amount of toner in the toner container 23 based on a change in detection light detected when the remaining amount detection windows 53 and 54 are wiped off by the mylar sheet 55. However, in this embodiment, when there is a lot of toner in the toner container 23, the remaining amount detection windows 53 and 54 are covered with toner immediately after the mylar sheet 55 cleans the remaining amount detection windows 53 and 54. Does not penetrate. Therefore, in the present embodiment, the remaining amount detection mechanism 5 detects that the remaining amount of toner is equal to or greater than a certain amount when the toner in the toner container 23 is large. As the amount of toner in the toner container 23 decreases, the light receiving unit 52 can detect the detection light, and the remaining amount of toner in the toner container 23 is detected based on the length of the detection time. be able to.

  In order to determine the deterioration state of the toner, it is only necessary to obtain information on the amount of toner in the toner container 23, and the configuration may be such that the amount of toner consumption is detected instead of the remaining amount of toner. Further, the configuration may be such that the toner remaining amount is determined from the toner consumption amount. The means for detecting the amount of toner is not limited to the optical detection type. For example, a capacitance type that detects the remaining amount of toner by using a change in capacitance between electrodes depending on the amount of toner or the presence or absence of toner may be used.

  In this embodiment, the remaining amount of toner when the cartridge P is new is defined as 100%. Further, the remaining amount of toner is defined as 0% when the detection time of the detection light reaches a predetermined detection time corresponding to a state where the toner is reduced to the extent that the cartridge P needs to be replaced. The CPU 26 stores the remaining amount of toner in the memory 50.

  In the image forming apparatus 100 of the present embodiment, when a durability test by continuous printing is performed at a high printing rate of 5%, even if auxiliary toner is supplied to the cleaning unit N from the cartridge P with a remaining amount of toner of 10% or less, It has been found that there is a high possibility that cleaning failure will occur. This is because this toner cannot maintain sufficient lubricity between the cleaning blade 21 and the intermediate transfer belt 8 because the toner is deteriorated. At that time, the toner deterioration index based on the BET value was also less than 80%. Therefore, in this embodiment, the remaining amount of toner of 10% is set as the threshold value for toner deterioration.

  Next, the index value of the deterioration state of the toner obtained based on the rotation speed of the developing roller 3 will be described. Here, the index value of the toner deterioration state obtained from the rotation speed of the developing roller 3 is referred to as “developer life”. Specifically, the CPU 26 calculates the total number of rotations (total number of rotations) of the developing roller 3 from the new state of the cartridge P, and stores the total number of rotations in the memory 50. Then, the CPU 26 obtains the developing device life based on the total number of rotations of the developing roller 3 stored in the memory 50. Note that the life of the developing device may be obtained from the total operation time (rotation time) instead of the total rotation speed.

  In this embodiment, the time when the cartridge P is new, that is, the time when the rotation speed of the developing roller 3 is zero is defined as a developing device life of 100%. A time point when the total number of revolutions reaches a predetermined threshold is defined as a developing device life of 0%. This predetermined threshold is set in advance by the number of rotations of the developing roller 3 corresponding to the state in which the developing roller 3 and the developing blade 31 have deteriorated to the extent that the cartridge P needs to be replaced in order to suppress various image defects.

  In the image forming apparatus 100 according to the present embodiment, when a durability test is performed by intermittently printing two sheets at a printing rate of 1%, the auxiliary toner is supplied to the cleaning unit N from the cartridge P having a developing device life of 10% or less. It has been found that there is a high possibility that defective cleaning will occur. This is because this toner cannot maintain sufficient lubricity between the cleaning blade 21 and the intermediate transfer belt 8 because the toner is deteriorated. At that time, the toner deterioration index based on the BET value was also less than 80%. Therefore, in this embodiment, the developing device life of 10% is set as the threshold for toner deterioration.

  In this embodiment, the toner deterioration state is determined from the toner remaining amount defined as described above and the developing device life (the number of rotations of the developing roller 3). As described above, which of the remaining amount of toner and the life of the developing device becomes the dominant factor of toner deterioration depends on the printing conditions. For this reason, in this embodiment, it is determined that the cartridge P is deteriorated when either the remaining amount of toner or the life of the developing device exceeds a predetermined threshold. That is, in this embodiment, the predetermined threshold values for the remaining amount of toner and the life of the developing device are 10%, respectively, and when either the remaining amount of toner or the life of the developing device becomes less than 10%, the cartridge in which the toner is deteriorated. J is determined to be P.

  In this embodiment, the deterioration state of the toner is determined from both the remaining amount of toner and the life of the developing device. However, this is acceptable from the viewpoint of maintaining sufficient lubricity between the cleaning blade 21 and the intermediate transfer belt 8. If so, it is possible to simplify and judge from only one of them.

7). Toner Supply Mode in the Present Embodiment Next, the toner supply mode in the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart illustrating the operation procedure of the toner supply mode according to the present exemplary embodiment. In this embodiment, the CPU 26 controls various judgments and instructions shown in FIG.

  When the execution timing of the toner supply mode arrives, the CPU 26 determines the presence or absence of a cartridge P that is determined to have deteriorated among the four cartridges P from the remaining amount of toner and the life of the developing device (S201).

  If the CPU 26 determines in S201 that there is no cartridge P for which it is determined that the toner has deteriorated, the toner in all the cartridges P sufficiently functions as a lubricant, so the toner supply mode is performed in the procedure of S101 to S105 in FIG. Execute. At this time, the supply toner image is a toner image for four colors of yellow, magenta, cyan, and black, each of which is a solid band image having a width of 206 mm in the main scanning direction and a length of 32 mm in the sub scanning direction.

  On the other hand, if the CPU 26 determines that there is a cartridge P in which toner is determined to have deteriorated in S201, the amount of auxiliary toner from the cartridge P in which the toner has deteriorated is reduced, and the amount of auxiliary toner from other cartridges P Is increased (S202). For example, if it is determined that the toner has deteriorated only in the yellow cartridge PY, and the other cartridges PM, PC, and PK have determined that the toner has not deteriorated, the following instruction is given. That is, an instruction is given to reduce the length in the sub-scanning direction of the supply toner image formed by the yellow cartridge PY determined to have deteriorated toner to 8 mm. In addition, an instruction is given to increase the length in the sub-scanning direction of the supply toner image formed by the other cartridges PM, PC, and PK to 40 mm. In another example, when it is determined that the toners of the yellow cartridge PY and the black cartridge PK have deteriorated and it is determined that the toners of the magenta cartridge PM and the cyan cartridge PC have not deteriorated, the following instruction is given. That is, it is instructed to reduce the length in the sub-scanning direction of the supply toner image formed by the yellow cartridge PY and the black cartridge PK, respectively, to 4 mm. In addition, an instruction is given to increase the length in the sub-scanning direction of the supply toner image formed by the magenta cartridge PM and the cyan cartridge PC to 60 mm. In other words, the total amount of auxiliary toner supplied to the cleaning unit N in the toner supply mode is set to be equal to or greater than a predetermined value, while the total amount of auxiliary toner supplied from the cartridge P determined to be deteriorated is equal to or less than the predetermined value. To be. In this way, by suppressing the total amount of deteriorated toner supplied to the cleaning unit N as auxiliary toner to a predetermined amount or less, the lubricity required for the auxiliary toner can be maintained.

  Note that the predetermined amount as the upper limit of the total amount of deteriorated toner supplied to the cleaning unit N as the auxiliary toner varies depending on the type of toner, development, and transfer configuration, and is not limited to the numerical values of the present embodiment. Similarly, the predetermined amount as the lower limit of the total amount of auxiliary toner supplied to the cleaning unit N in the toner supply mode is not limited to the numerical value of the present embodiment. In this embodiment, the amount of auxiliary toner is controlled by changing the exposure time (exposure amount) of the laser unit 7, but the present invention is not limited to this. As is normally done in electrophotography, the amount of auxiliary toner can be controlled by controlling at least one of the exposure amount of the exposure means, the charging bias, the developing bias, and the primary transfer bias.

  Next, the CPU 26 rotates the photosensitive drum 1 and the intermediate transfer belt 8 (S203) and shifts to an image formation standby state (S204). Then, the CPU 26 forms a supply toner image on the photosensitive drum 1 of each image forming unit I, and transfers the supply toner image to the intermediate transfer belt 8 (S205). At this time, according to the instruction in S202, the CPU 26 shortens the exposure time by the laser unit 7 when forming the supply toner image with the cartridge P determined to have deteriorated toner. Further, the exposure time by the laser unit 7 when the supply toner image is formed by the other cartridge P is lengthened.

  Next, in the same manner as S104 and S105 in FIG. 3, the CPU 26 allows the supply toner image to pass through the secondary transfer portion T2 (S206) and causes the auxiliary toner to reach the cleaning portion N (S207).

  In the image forming apparatus 100 of the present embodiment, when a durability test by intermittent printing of two sheets at a low printing rate of 1% is performed, no cleaning failure occurs even after outputting 40,000 sheets of images when the cartridge P is replaced. It was.

  In this embodiment, the amount of auxiliary toner supplied from the cartridge P determined to have deteriorated is reduced, but the present invention is not limited to this. The auxiliary toner may not be supplied from the cartridge P determined that the toner has deteriorated, but may be supplied only from the other cartridge P in which it is determined that the toner has not deteriorated. However, by using the deteriorated toner as the auxiliary toner as long as sufficient lubricity between the cleaning blade 21 and the intermediate transfer belt 8 can be maintained, the amount of the non-deteriorated toner used as the auxiliary toner can be reduced. .

  In this embodiment, auxiliary toner is supplied from all four cartridges P, but the present invention is not limited to this. For example, when it is determined that the toner of all the cartridges P has not deteriorated, the auxiliary toner may be supplied from only one or a plurality of cartridges P that are not all of the four cartridges P. In addition, among the four cartridges P, auxiliary toner is supplied only from a plurality of cartridges P that are not all, including the cartridge P that is determined to have deteriorated toner and the cartridge P that is determined not to have deteriorated toner. You may make it do. Also in this case, according to the present embodiment, the amount of auxiliary toner supplied from the cartridge P determined that the toner has deteriorated is smaller than the amount of auxiliary toner supplied from the cartridge P determined that the toner has not deteriorated. To do.

  As described above, in this embodiment, the image forming apparatus 100 includes a detecting unit that detects an index value correlated with the deterioration state of the toner stored in the developing device 30 for each of the plurality of image forming units I. In the present exemplary embodiment, in the image forming apparatus 100, the detection unit rotates the remaining amount detection mechanism 5 as the remaining amount detection unit that detects the remaining amount of toner and the rotation number (or rotation time) of the developing roller 3. The CPU 26 is configured as number detection means (or rotation time detection means). Further, the image forming apparatus 100 includes a control unit 26 that executes a supply operation for supplying toner to the cleaning unit N. In this supply operation, the supply toner image is transferred from at least one of the plurality of image forming units I to the transport body 8 and transported by the transport body 8 to supply the toner of the supply toner image to the cleaning unit N. Supply.

  When there is an image forming unit I in which the index value exceeds a predetermined threshold in a direction in which the degree of toner deterioration is large and an image forming unit I in which the index value does not exceed, among the plurality of image forming units I. Control as follows. That is, an image in which the index value does not exceed the threshold value of the toner amount of the supply toner image transferred from the image forming unit I in which the index value exceeds the threshold value in the image forming unit I that transfers the supply toner image to the conveyance body 8. Control is performed so that the toner amount of the supply toner image transferred from the forming unit I is smaller than the toner amount. Alternatively, the supply toner image is controlled to be transferred only from at least one image forming unit I whose index value does not exceed the threshold among the plurality of image forming units I. At this time, when the supply toner image is transferred from at least one image forming unit I whose index value exceeds the threshold value, the total amount of toner of the supply toner image transferred from the image forming unit whose index value exceeds the threshold value is predetermined. It is preferable to control so that it is below the value. Further, it is preferable to control the total amount of toner of the supply toner image supplied to the cleaning unit N so as to be equal to or greater than a predetermined value.

  In other words, in this embodiment, among the plurality of image forming units I, the image forming unit I whose index value is the first value and that the degree of toner deterioration is greater than when the index value is the first value. The toner image for supply can be transferred to the conveyance body 8 from the image forming unit I having the second value shown. At this time, the toner amount of the supply toner image transferred from the image forming portion having the index value of the second value is made smaller than the toner amount of the supply toner image transferred from the image forming portion having the index value of the first value. . Of the image forming unit I that transfers the supply toner image to the conveyance body 8, the image forming unit I whose index value indicates that the degree of toner deterioration is small, the toner of the supply toner image transferred from the image forming unit I You can also increase the amount.

  As described above, according to the present exemplary embodiment, sufficient lubricity between the cleaning member 21 and the intermediate transfer belt 8 can be obtained even in a situation where the cartridge P including the developing device 30 has a longer life and the toner is more likely to deteriorate. Can be maintained. As a result, the life of the cartridge P including the developing device 30 is extended, and even when the toner is more deteriorated, it is possible to prevent the tip of the cleaning blade 21 from being turned over and the occurrence of defective cleaning.

[Example 2]
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Therefore, in the image forming apparatus of the present embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, when there is a cartridge P that is determined to have deteriorated when the toner supply mode is executed, the auxiliary toner is supplied only from the cartridge P with the least degree of toner deterioration among the other cartridges P. Supply to cleaning unit N.

  With reference to FIG. 5, the toner supply mode in this embodiment will be described. FIG. 5 is a flowchart illustrating the operation procedure of the toner supply mode according to the present exemplary embodiment. In this embodiment, the CPU 26 controls various judgments and instructions shown in FIG.

  When the execution timing of the toner supply mode arrives, the CPU 26 determines the presence or absence of a cartridge P for which it is determined that the toner has deteriorated among the four cartridges P based on the remaining amount of toner and the life of the developing device (S301).

  If the CPU 26 determines in S301 that there is no cartridge P for which it is determined that the toner has deteriorated, the toner in all the cartridges P functions sufficiently as a lubricant, so the toner supply mode is performed in the steps S101 to S105 in FIG. Is executed.

  On the other hand, if the CPU 26 determines that there is a cartridge P in which the toner is determined to have deteriorated in S301, among the cartridges P other than the cartridge P in which the toner is determined to be deteriorated, the cartridge having the smallest degree of toner deterioration. P is designated (S302). For example, it is assumed that the yellow cartridge PY has a developer life of 7% and it is determined that the toner has deteriorated. It is also assumed that the remaining amount of toner in the magenta cartridge PM is 50%, the developing device life of the cyan cartridge PC is 60%, and the remaining amount of toner in the black cartridge PK is 90%. In this case, the black cartridge PK is designated.

  Next, the CPU 26 rotates the photosensitive drum 1 and the intermediate transfer belt 8 (S303) and shifts to an image formation standby state (S304). Then, the CPU 26 forms a supply toner image only with the cartridge P designated in S302, and transfers the supply toner image to the intermediate transfer belt 8 (S305). At this time, the CPU 26 sets the exposure time by the laser unit 7 when forming the supply toner image with the designated cartridge P to a predetermined time longer than when forming the supply toner images with the plurality of cartridges P. For example, when the black cartridge PK is designated, the supply toner image formed by the black cartridge PK is a solid band image having a width in the main scanning direction of 206 mm and a length in the sub scanning direction of 128 mm. That is, the total amount of auxiliary toner supplied to the cleaning unit N in the toner supply mode is set to be equal to or greater than the same predetermined value as when auxiliary toner is supplied from the four cartridges P.

  Thereafter, in the same manner as S104 and S105 in FIG. 3 or S206 and S207 in FIG. 4, the CPU 26 allows the supply toner image to pass through the secondary transfer portion T2 (S306), and removes the auxiliary toner to the cleaning portion N. (S307).

  In the image forming apparatus 100 of the present embodiment, when a durability test by intermittent printing of two sheets at a low printing rate of 1% is performed, no cleaning failure occurs even after outputting 40,000 sheets of images when the cartridge P is replaced. It was.

  In this embodiment, the auxiliary toner is supplied from the cartridge P having the smallest degree of toner deterioration among the cartridges P determined that the toner has not deteriorated, so that only the toner having higher lubricity is removed from the cleaning unit N. Can be supplied to. For this reason, the total amount of auxiliary toner supplied to the cleaning unit N in the toner supply mode is reduced from that in the first embodiment if it is allowable from the viewpoint of maintaining sufficient lubricity between the cleaning blade 21 and the intermediate transfer belt 8. It is also possible.

  In this embodiment, the auxiliary toner is supplied only from the cartridge P having the smallest degree of toner deterioration among the cartridges P determined that the toner has not deteriorated. As another method, it is also possible to increase the amount of auxiliary toner to be supplied to a cartridge P having a smaller degree of toner deterioration, as the auxiliary toner is supplied from a plurality of cartridges P determined that the toner has not deteriorated. is there. Also in this case, it is possible to supply more cleaning toner N with less lubrication and higher lubricity. Therefore, as described above, the total amount of auxiliary toner supplied to the cleaning unit N in the toner supply mode can be reduced as compared with the first embodiment as desired.

  As described above, in this embodiment, the control unit 26 includes the image forming unit I having an index value that correlates with the toner deterioration state of the plurality of image forming units I and the image forming unit I not exceeding the threshold value. If there is, control as follows. That is, among the plurality of image forming units I, the supply toner image is transferred only from the image forming unit I that indicates that the index value does not exceed the threshold value and the index value indicates the smallest degree of toner deterioration. To control. Further, the supply toner image can be transferred only from the plurality of image forming units I whose index values do not exceed the threshold among the plurality of image forming units I. In this case, among the image forming units I that transfer the supply toner image to the conveyance body 8, the image forming unit I whose index value indicates that the degree of deterioration of the toner is small is transferred from the image forming unit I. The amount of toner can be increased.

  As described above, according to this embodiment, the same effect as that of the embodiment can be obtained, and sufficient lubricity between the cleaning blade 21 and the intermediate transfer belt 8 can be easily maintained.

[Example 3]
Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the first embodiment. Therefore, in the image forming apparatus of the present embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, when it is determined that the toner of all the cartridges P has deteriorated, the toner supply mode is executed as follows as a provisional measure until the replacement of the cartridges P. That is, the auxiliary toner is supplied to the cleaning unit N only from the cartridge P having the smallest degree of toner deterioration among the cartridges P.

  With reference to FIG. 6, the toner supply mode in this embodiment will be described. FIG. 6 is a flowchart illustrating the operation procedure of the toner supply mode according to the present exemplary embodiment. In this embodiment, the CPU 26 controls various judgments and instructions shown in FIG.

  When the execution timing of the toner supply mode arrives, the CPU 26 determines the presence or absence of the cartridge P for which it is determined that the toner has deteriorated among the four cartridges P from the remaining amount of toner and the life of the developing device (S401).

  If the CPU 26 determines in S401 that there is no cartridge P for which it is determined that the toner has deteriorated, the toner in all the cartridges P functions sufficiently as a lubricant, and therefore the toner supply mode is performed in the steps S101 to S105 in FIG. Is executed.

  If the CPU 26 determines in step S401 that the toner in some of the cartridges P has deteriorated, the CPU 26 causes the toner supply mode to be executed in the sequence of steps S302 to S307 in FIG. Here, the toner supply mode may be executed in the sequence of S202 to S207 in FIG.

  On the other hand, when the CPU 26 determines that the toner of all the cartridges P has deteriorated in S401, the CPU 26 designates the cartridge P having the smallest degree of toner deterioration among the cartridges P determined to have deteriorated (S402). For example, assume that the remaining amount of toner in the yellow cartridge PY is 2%, the remaining amount of toner in the magenta cartridge PM is 1%, the developing device life of the cyan cartridge PC is 3%, and the remaining amount of toner in the black cartridge PK is 9%. . In this case, the black cartridge PK is designated. Although the toner of the black cartridge PK is deteriorated, since the degree of deterioration is smaller than that of the other cartridges P, a life extension effect can be expected as compared with the case where the toner of the other cartridges is used as the auxiliary toner.

  Next, the CPU 26 rotates the photosensitive drum 1 and the intermediate transfer belt 8 (S403) and shifts to an image formation standby state (S404). Then, the CPU 26 forms a supply toner image only with the cartridge P designated in S402, and transfers the supply toner image to the intermediate transfer belt 8 (S405). At this time, the CPU 26 sets the exposure time by the laser unit 7 when forming the supply toner image to a predetermined time longer than the exposure time in S305 of FIG. For example, when the black cartridge PK is designated, the supply toner image formed by the black cartridge PK is a solid band image having a width in the main scanning direction of 206 mm and a length in the sub scanning direction of 256 mm. In other words, the amount of auxiliary toner is increased by increasing the length of the solid band image in the sub-scanning direction, and the lubricity as the total amount of auxiliary toner is ensured as much as the lubricity of one toner is reduced due to deterioration. .

  Thereafter, the CPU 26 causes the supply toner image to pass through the secondary transfer portion T2 in the same manner as in S104 and S105 in FIG. 3, S206 and S207 in FIG. 4, or S306 and S307 in FIG. 5 (S306). The auxiliary toner reaches the cleaning unit N (S307).

  As described above, when the toner of all the cartridges P is deteriorated, the auxiliary toner is supplied from the cartridge P with the smallest degree of toner deterioration, thereby suppressing the turning-up of the tip of the cleaning blade 21 and the occurrence of defective cleaning. Can do. However, as described above, this control is performed as a provisional life extension measure until the cartridge P is replaced. Therefore, when it is determined in S401 that the toner of all the cartridges P has deteriorated, it is preferable to alert the user to replace the cartridges P. In this case, for example, before S402 or after S407, the CPU 26 may display a warning (error display) on the display screen of the operation unit 28 (FIG. 1) of the apparatus main body 110 as a notification unit. it can. As described above, the control of the present embodiment is desirably performed in combination with the control of the toner supply mode of the first or second embodiment.

  In this embodiment, the auxiliary toner is supplied only from the cartridge P having the smallest degree of toner deterioration among the cartridges P determined to be deteriorated. As another method, it is also possible to increase the amount of auxiliary toner supplied to a cartridge P with a smaller degree of toner deterioration, as the auxiliary toner is supplied from a plurality of cartridges P that are determined to have deteriorated toner. In this case as well, it is possible to supply more cleaning toner N to the cleaning unit N although it is deteriorated.

  As described above, in this embodiment, when the index value correlated with the deterioration state of all the toners of the plurality of image forming units I exceeds the threshold value, the control unit 26 performs the following control. That is, control is performed so that the supply toner image is transferred only from the image forming unit I whose index value indicates that the degree of toner deterioration is the smallest among the plurality of image forming units I. In addition, the supply toner images can be transferred from the plurality of image forming units I whose index values exceed the threshold among the plurality of image forming units I. In this case, among the image forming units I that transfer the supply toner image to the conveyance body 8, the image forming unit I whose index value indicates that the degree of deterioration of the toner is small is transferred from the image forming unit I. The amount of toner can be increased.

[Others]
The present invention has been described with reference to specific embodiments. However, the present invention is not limited to the above-described embodiments.

  For example, in the above-described embodiment, the case where the present invention is applied to an intermediate transfer type image forming apparatus has been described. However, the present invention is not limited to this, and can be applied to a direct transfer type image forming apparatus, and the same effects as described above can be obtained. FIG. 7 is a schematic cross-sectional view of a main part of a direct transfer type image forming apparatus. In FIG. 7, elements having the same or corresponding functions or configurations as those of the image forming apparatus of FIG. An image forming apparatus 100 shown in FIG. 7 has a recording material carrying belt (conveying belt) 29 formed of an endless belt as a recording material carrying body, instead of the intermediate transfer belt 8 in the image forming apparatus 100 shown in FIG. . The recording material carrying belt 29 is an example of a conveyance body that conveys a recording material onto which toner images are transferred from the image carrying bodies of a plurality of image forming units. In the image forming apparatus 100 of FIG. 7, the toner image formed on the photosensitive drum 1 in each image forming unit I is recorded on the recording material carrying belt by the action of the transfer voltage applied to each transfer roller 6 in each transfer unit T. The recording material S is transferred onto the recording material S that is carried and conveyed on the recording medium S. Also in such an image forming apparatus 100, toner may adhere to the recording material carrying belt 28 in an image output operation or a calibration operation. In order to remove the toner, a cleaning blade 21 similar to that in the above-described embodiment is disposed in contact with the recording material carrying belt 28. Therefore, the present invention can be applied to such an image forming apparatus 100 in order to maintain sufficient lubricity between the cleaning blade 21 and the recording material carrying belt 28, and the same effect as described above can be obtained. Can be obtained.

  In the above-described embodiments, the developing device is detachable from the apparatus main body of the image forming apparatus together with the photosensitive drum, but the developing device is detachable from the apparatus main body of the image forming apparatus alone. Also good.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 3 Developing roller 6 Primary transfer roller 7 Laser unit 8 Intermediate transfer belt 11 Secondary transfer roller 21 Cleaning blade 26 CPU
50 memory P cartridge

Claims (13)

A plurality of image forming units each having an image carrier that carries a toner image, and a developer that contains the toner and supplies the toner to the image carrier to form a toner image;
A carrier for conveying a toner image transferred from the image carrier of the plurality of image forming units or a recording material on which a toner image is transferred from the image carrier of the plurality of image forming units;
A cleaning member that forms a cleaning portion in contact with the transport body;
In an image forming apparatus having
Detecting means for detecting an index value correlated with a deterioration state of toner stored in the developing unit for each of the plurality of image forming units;
Supply operation for supplying toner to the cleaning unit, wherein a toner image for transfer is transferred from at least one of the plurality of image forming units to the conveying member and conveyed by the conveying member, and the cleaning unit Control means for executing a supply operation for supplying toner of the supply toner image to
Have
When the control unit includes an image forming unit in which the index value exceeds a predetermined threshold in a direction in which the degree of toner deterioration is large and an image forming unit in which the index value does not exceed the image forming unit, Among the image forming units that transfer the supply toner image, the index value exceeds the threshold value for the toner amount of the supply toner image transferred from the image forming unit whose index value exceeds the threshold value to the transport body. Control so as to be less than the toner amount of the supply toner image transferred from the non-image forming unit to the transport body, or at least the index value of the plurality of image forming units does not exceed the threshold value An image forming apparatus, wherein the supply toner image is controlled to be transferred from only one image forming unit to the conveyance body.   When there is an image forming unit in which the index value exceeds the threshold value and an image forming unit in which the index value does not exceed the threshold value among the plurality of image forming units, the control unit has the index value out of the plurality of image forming units. Control is performed so that the supply toner image is transferred to the transport body only from an image forming unit that does not exceed the threshold and the index value indicates that the degree of toner deterioration is the smallest. The image forming apparatus according to claim 1.   When there is an image forming unit in which the index value exceeds the threshold value and an image forming unit in which the index value does not exceed the threshold value among the plurality of image forming units, the control unit has the index value out of the plurality of image forming units. The index value of the image forming unit that transfers the supply toner image to the transport body from only a plurality of image forming units that do not exceed the threshold value and transfers the supply toner image to the transport body is a toner. The image forming unit indicating that the degree of deterioration of the toner is small is controlled so that the amount of toner of the supply toner image transferred from the image forming unit to the conveyance body is increased. Image forming apparatus.   When all the index values of the plurality of image forming units exceed the threshold value, the control unit indicates that the index value of the plurality of image forming units has the least degree of toner deterioration. 4. The image forming apparatus according to claim 1, wherein the supply toner image is controlled to be transferred from only the image forming unit to the conveyance body. 5.   When all the index values of the plurality of image forming units exceed the threshold value, the control unit includes a plurality of image forming units from which the index value exceeds the threshold value. Among the image forming units that transfer the supply toner image to the transport body and transfer the supply toner image to the transport body, the image forming unit indicates that the index value indicates a small degree of toner deterioration. 4. The image forming apparatus according to claim 1, wherein the toner amount of the supply toner image transferred from the image forming unit to the conveyance body is increased. 5.   In the case where the supply toner image is transferred to the transport body from at least one image forming unit in which the index value exceeds the threshold, the control unit transfers the transport from the image forming unit in which the index value exceeds the threshold. The image forming apparatus according to claim 1, wherein the total amount of toner of the supply toner image transferred to the body is controlled to be a predetermined value or less.   The image forming apparatus according to claim 1, wherein the control unit controls the total amount of toner of the supply toner image supplied to the cleaning unit to be a predetermined value or more. apparatus. A plurality of image forming units each having an image carrier that carries a toner image, and a developer that contains the toner and supplies the toner to the image carrier to form a toner image;
A carrier for conveying a toner image transferred from the image carrier of the plurality of image forming units or a recording material on which a toner image is transferred from the image carrier of the plurality of image forming units;
A cleaning member that forms a cleaning portion in contact with the transport body;
In an image forming apparatus having
Detecting means for detecting an index value correlated with a deterioration state of toner stored in the developing unit for each of the plurality of image forming units;
Supply operation for supplying toner to the cleaning unit, wherein a toner image for transfer is transferred from at least one of the plurality of image forming units to the conveying member and conveyed by the conveying member, and the cleaning unit Control means for executing a supply operation for supplying toner of the supply toner image to
Have
The control means indicates that the index value is the first value among the plurality of image forming portions, and that the degree of toner deterioration is greater than when the index value is the first value. The toner of the supply toner image, which is transferred from the image forming unit having the second value to the conveying member, and transferred from the image forming unit having the second value to the conveying member. An image forming apparatus, wherein the amount is controlled to be smaller than a toner amount of the supply toner image transferred from the image forming unit having the index value of the first value to the conveyance body.   The image forming apparatus according to claim 1, wherein the index value is a value based on an amount of toner accommodated in the developing device.   The index value is a value based on a rotation number or a rotation time of a rotatable developer carrying member that carries the toner of the developing unit and conveys the toner to the image carrier. The image forming apparatus according to claim 8.   The index value is based on the amount of toner accommodated in the developing device and the number of rotations or the rotation time of a rotatable developer carrying member that carries the toner of the developing device and conveys it to the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is a value.   The image forming apparatus according to claim 1, wherein the conveyance body is an endless belt.   The image forming apparatus according to claim 1, wherein a cartridge including the developing device is detachable from an apparatus main body of the image forming apparatus.

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