JP4649893B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine or a laser printer. More specifically, the present invention relates to an image forming apparatus that transfers an image formed on an image carrier onto a recording material via an intermediate transfer member.

  As a conventional image forming apparatus, for example, a photosensitive drum on which a toner image corresponding to an electrostatic latent image is formed, an intermediate transfer belt on which the toner image on the photosensitive drum is intermediately transferred, and the intermediate transfer belt On the other hand, there is known a device including a primary transfer device that transfers a toner image on a photosensitive drum and a secondary transfer device that collectively transfers a toner image transferred onto an intermediate transfer belt onto a sheet. Here, as the secondary transfer device, for example, a secondary transfer roll disposed in contact with the toner image carrying surface of the intermediate transfer belt and a backup roll disposed opposite to the secondary transfer roll with the intermediate transfer belt interposed therebetween. A device to which a secondary transfer bias is applied is used.

  In this type of image forming apparatus, it is necessary to remove residual toner remaining on the photosensitive drum after primary transfer and residual toner remaining on the intermediate transfer belt after secondary transfer. Therefore, for example, a blade or the like is placed in pressure contact with a photosensitive drum, intermediate transfer belt, or paper transport belt to be cleaned, and residual toner or the like is scraped off (see Patent Documents 1 and 2).

Further, in such an image forming apparatus, when the paper passes through the secondary transfer device, the paper dust of the paper is transferred and attached to the intermediate transfer belt. The paper dust adhering to the intermediate transfer belt can be scraped off by the blade described above, but the paper dust may be caught between the blade and the intermediate transfer belt. As a result, a gap is generated between the blade and the intermediate transfer belt, and residual toner slips through, resulting in poor cleaning.
Therefore, in order to deal with such a problem, in Patent Documents 1 and 2 described above, the intermediate transfer belt (paper transport belt) is rotated in a direction opposite to that at the time of image formation at a predetermined timing, for example, after completion of image formation. There is disclosed a technique in which paper dust is removed from a blade by moving it.

JP-A-9-160399 (page 2-3, FIG. 2) Japanese Patent Laid-Open No. 10-10939 (page 4, FIG. 2)

By the way, when the paper dust passes through the secondary transfer device, it transfers and adheres not only to the intermediate transfer belt but also to the secondary transfer roll. Usually, the secondary transfer roll is provided with a blade or the like for removing toner transferred from the intermediate transfer belt, such as toner constituting a patch image formed in the inter-image area of the intermediate transfer belt. If the toner is caught between the blade and the secondary transfer roll, the residual toner slips out as described above, and the back surface of the paper is soiled.
With respect to such a problem, the above-described Patent Documents 1 and 2 do not assume such a problem, and thus cannot prevent such back-side contamination of the paper.

The present invention has been made to solve such a technical problem, and an object of the present invention is to remove paper dust adhering to the cleaner of the intermediate transfer member and the cleaner of the secondary transfer member with a simple configuration. It is to remove both.
Another object is to prevent the image carrier from being damaged when the intermediate transfer member is reversely rotated to remove paper dust.

  For this purpose, an image forming apparatus to which the present invention is applied includes an image carrier that is rotatably arranged to form and carry a toner image, and a toner image that is rotatably arranged and carried on the image carrier. The intermediate transfer member on which the toner image is primary-transferred, the secondary transfer member that is rotatably arranged and secondarily transfers the toner image primary-transferred to the intermediate transfer member to the recording material, and the intermediate transfer member after the secondary transfer. The first cleaning means, the second cleaning means for cleaning the secondary transfer member after the secondary transfer, and the first cleaning means by rotating the intermediate transfer member in the direction opposite to that during the secondary transfer. A certain paper dust is removed, and the paper dust in the second cleaning means is removed by rotating the secondary transfer member in the reverse direction to the secondary transfer in conjunction with the rotation of the intermediate transfer member in the reverse direction. Paper dust removing means.

  Here, the secondary transfer member can be characterized in that it is disposed in pressure contact with the intermediate transfer member and rotates in the reverse direction of the secondary transfer following the rotation of the intermediate transfer member in the reverse direction. The first cleaning means includes a blade that is disposed in pressure contact with the rotational direction of the intermediate transfer member during the secondary transfer in the counter direction, and the second cleaning means includes a secondary transfer member secondary contact. It can be characterized by having a blade press-contacted in the counter direction with respect to the rotation direction at the time of transfer. And a third cleaning unit for cleaning the image carrier after the primary transfer, and a reverse rotation unit for rotating the image carrier in the reverse direction in conjunction with the rotation of the intermediate transfer member in the reverse direction. Can be a feature. The paper dust removing means can perform the paper dust removing operation after completion of the image forming operation and / or whenever the number of prints reaches a predetermined number.

  From another viewpoint, the present invention primarily transfers a toner image formed by a plurality of image carriers to an intermediate transfer member, and then secondary transfer the toner image primarily transferred to the intermediate transfer member to a recording material. A tandem type image forming apparatus, a secondary transfer unit for secondary transfer of a toner image primarily transferred to an intermediate transfer member to a recording material, and an intermediate transfer cleaning unit for cleaning the intermediate transfer member after the secondary transfer A secondary transfer cleaning means for cleaning the secondary transfer means after the secondary transfer, a retract means for separating at least one of the plurality of image carriers from the intermediate transfer body, and at least from the intermediate transfer body by the retract means. With one image carrier separated, the intermediate transfer member is rotated in the opposite direction to the secondary transfer to remove paper dust from the intermediate transfer cleaning means, and the intermediate transfer member is rotated in the opposite direction. Secondary transfer means in conjunction with The time of the secondary transfer and a paper dust removing means for removing the paper dust in the secondary transfer cleaning unit by rotating in the opposite direction.

  Here, the plurality of image carriers include a yellow image carrier that forms and supports a yellow toner image, a magenta image carrier that forms and supports a magenta toner image, and a cyan image carrier that forms and supports a cyan toner image. And a black image carrier that forms and carries a black toner image, and the retracting means separates the yellow image carrier, the magenta image carrier, and the cyan image carrier from the intermediate transfer member. It can be. Further, the image forming apparatus may further include a reverse rotation unit that rotates the image carrier that is not separated from the intermediate transfer member by the retracting unit in conjunction with the rotation of the intermediate transfer member in the reverse direction. In this case, the reverse rotation speed of the intermediate transfer member may be different from the reverse rotation speed of the image carrier that is not separated. Further, the intermediate transfer cleaning means has a blade arranged in pressure contact with the rotational direction during secondary transfer of the intermediate transfer body in the counter direction, and the secondary transfer cleaning means is a secondary transfer of the secondary transfer means. It can be characterized by having a blade press-contacted in the counter direction with respect to the rotational direction of the hour. The retracting unit keeps at least one image carrier separated from the intermediate transfer member after completion of the image forming operation and / or every time the number of printed sheets reaches a predetermined number of sheets, and the paper dust removing unit The paper dust removing operation may be started after at least one image carrier is separated from the intermediate transfer member by the retracting means.

  According to the present invention, paper dust adhering to the cleaner of the intermediate transfer member and the cleaner of the secondary transfer member can be removed with a simple configuration.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the accompanying drawings.
FIG. 1 shows an image forming apparatus to which the exemplary embodiment is applied. This is a so-called tandem type or intermediate transfer type image forming apparatus, for example, a plurality of image forming units 10 (specifically, 10Y, 10M, 10C, 10K) on which each color component toner image is formed by electrophotography. ), An intermediate transfer belt 20 as an intermediate transfer body for sequentially transferring (primary transfer) and holding each color component toner image formed in each image forming unit 10, and a superimposed image transferred on the intermediate transfer belt 20. A secondary transfer device 30 as a secondary transfer means for secondary transfer (collective transfer) to a paper P as a recording material, and a fixing device 40 for fixing the secondary transferred image on the paper P. is there.

  In the present embodiment, each image forming unit 10 includes a photosensitive drum 11 (specifically, 11Y, 11M, 11C, and 11K) as an image carrier that rotates in the direction of arrow A. Among the photosensitive drums 11, the diameters of the yellow, magenta, and cyan photosensitive drums 11Y, 11M, and 11C are φ60, and the diameter of the black photosensitive drum 11K is φ80. Details of each image forming unit 10 will be described later.

  Further, the intermediate transfer belt 20 is stretched over a plurality of support rolls 21 to 27 and is rotated in the direction of arrow B. Here, the support roll 21 is a drive roll for rotating the intermediate transfer belt 20, and the support roll 22 is moved in a direction in which tension is applied to the intermediate transfer belt 20 or in the reverse direction, thereby moving the intermediate transfer belt 20 to yellow, magenta, Retract rolls and support rolls 23 that come into contact with and separate from the cyan photoconductor drums 11Y, 11M, and 11C are idle rolls and support rolls 24 that position the black photoconductor drum 11K and the intermediate transfer belt 20 regardless of the position of the retract roll 22. Is a sensor roll for positioning the black photosensitive drum 11K and the intermediate transfer belt 20 together with the idle roll 23, and a support roll 25 for adjusting the tension applied to the intermediate transfer belt 20. The tension roll and the support roll 26 are connected to the secondary transfer device 30. Pre-roll to position the surface of the intermediate transfer belt 20 in arranged in the secondary transfer position in the flow side, the support roll 27 is a backup roll of the secondary transfer device 30 to be described later. Further, on the inner side of the intermediate transfer belt 20 and on the upstream side of the driving roll 21 in the rotation direction of the intermediate transfer belt 20, a brush facing roll 28 and a blade facing roll disposed to face a belt cleaner 60 described later. 29. Here, the intermediate transfer belt 20 is made of a resin such as polyimide or polyamide containing an appropriate amount of an electron conductive material. The reference sensor 51 recognizes a patch image or the like formed on the surface of the intermediate transfer belt 20 and generates a reference signal. Based on the recognition of the reference signal, each image forming unit 10 (10Y, 10M). , 10C, 10K) are configured to start image formation.

  Further, the secondary transfer device 30 is disposed on the back side of the intermediate transfer belt 20 as a secondary transfer roll 31 as a secondary transfer member pressed against the toner image carrying surface of the intermediate transfer belt 20 and is subjected to secondary transfer. And a backup roll 27 serving as a counter electrode of the roll 31. A metal power supply roll 32 is disposed in contact with the backup roll 27. The secondary transfer bias is supplied to the secondary transfer roll 31 by a power source (not shown) and is grounded via a power supply roll 32 disposed in contact with the backup roll 27.

  Further, the secondary transfer roll 31 is provided with a roll cleaner 33 as a second cleaning means (secondary transfer cleaning means) for cleaning the surface of the secondary transfer roll 31 after the secondary transfer. The term “after secondary transfer” may be any time after the secondary transfer is completed and before the next secondary transfer is started. Here, the roll cleaner 33 includes a cleaning brush 34 disposed in contact with the secondary transfer roll 31 on the downstream side of the secondary transfer position of the secondary transfer roll 31, and a cleaning blade (blade) provided on the downstream side of the cleaning brush 34. ) 35, a block 36 for supplying zinc stearate as a release agent to the cleaning brush 34, a flip cover 37 that is fixedly disposed so as to come into contact with the cleaning brush 34 and removes paper dust attached to the cleaning brush 34, and the like A roll cleaner housing 38 is provided for housing each element. Further, a belt cleaner 60 for cleaning the surface of the intermediate transfer belt 20 after the secondary transfer is provided on the downstream side in the rotational direction of the intermediate transfer belt 20 as viewed from the secondary transfer device 30. In addition, an edge sensor 52 that detects a direction end perpendicular to the moving direction of the intermediate transfer belt 20 is provided upstream and inside the rotational direction of the intermediate transfer belt 20 relative to the idle roll 23.

  Further, the paper transport system feeds the paper P sent out from the paper tray (not shown) at a predetermined timing by the registration roll 71 and feeds it to the secondary transfer position of the secondary transfer device 30 via the transport chute 72. ing. Then, the sheet P after the secondary transfer is conveyed to the fixing device 40 via the guide member 73, the belt conveyance device 74, and the discharge guide 75.

  A belt cleaner 60 as a first cleaning unit (intermediate transfer cleaning unit) includes a cleaning brush 61 disposed opposite to the brush facing roll 28 on the most upstream side in the rotational direction of the intermediate transfer belt 20, and a cleaning brush 61. Also, a cleaning blade (blade) 62 disposed on the downstream side and opposed to the blade-facing roll 29, a scraper 63 provided further downstream than the cleaning blade 62, and the cleaning brush 61, the cleaning blade 62, and the scraper 63 are accommodated. The belt cleaner housing 64 and the seal 65 provided so that the free end is in contact with the intermediate transfer belt 20 on the most upstream side of the belt cleaner housing 64.

  FIG. 2 shows the image forming unit 10 shown in FIG. This configuration is common to the image forming units 10Y, 10M, 10C, and 10K except that the size of the photosensitive drum 11 is larger by 11K. The image forming unit 10 includes a charger 12 that charges the photosensitive drum 11 around the photosensitive drum 11, a laser exposure device 13 that writes an electrostatic latent image on the photosensitive drum 11, and an image forming unit 10. A developing device 14 that stores different color component toners to visualize an electrostatic latent image on the photosensitive drum 11, and a primary transfer roll 15 that transfers each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 20. In addition, an electrophotographic device such as a drum cleaner 16 as a third cleaning means for removing residual toner remaining on the photosensitive drum 11 after the primary transfer is disposed.

  Here, the photosensitive drum 11 is formed by forming an organic photosensitive layer on the surface of a metal thin cylindrical drum. The charger 12 is formed of, for example, a corotron, and discharges the photosensitive drum 11 to charge the photosensitive drum 11 to a predetermined potential. Further, the laser exposure unit 13 performs exposure by laser scanning according to the image signal, and changes the surface potential of the photosensitive drum 11 charged by the charger 12, thereby generating an electrostatic latent image according to the image information. Form. Furthermore, each of the developing devices 14 incorporates a two-component developer in which yellow, magenta, cyan, and black toners are mixed with a carrier formed by coating a magnetic material with a semiconductive material. Each color component toner is reversely developed on the exposed portion of the surface of the photosensitive drum 11. In addition, a voltage having a polarity opposite to the charging polarity of the toner is applied to the primary transfer roll 15, and the primary transfer roll 15 is formed on the photosensitive drum 11 due to a potential difference formed with the photosensitive drum 11. The toner image is transferred to the intermediate transfer belt 20.

  The drum cleaner 16 accommodates the cleaning blade 17 pressed against the rotation direction A of the photosensitive drum 11 in the counter direction, and the residual toner scraped off by the cleaning blade 17 to which the cleaning blade 17 is attached. A drum cleaner housing 18 and a seal 19 having one end mounted on the drum cleaner housing 18 on the upstream side of the cleaning drum 17 in the rotational direction of the photosensitive drum 11 and the other end in contact with the photosensitive drum 11 are provided. Yes.

  By the way, in the image forming apparatus according to the present embodiment, it is possible to form a full-color image using four colors of YMCK toner, and it is also possible to form a black and white image using a single color toner of K. It is. That is, when forming a black and white image, the other three colors (YMC) of K are unnecessary. Therefore, in the present embodiment, in the full color mode for forming a full color image, each of the photosensitive drums 11Y, 11M, 11C, and 11K is in contact with the intermediate transfer belt 20. In the monochrome mode for forming a monochrome image, only the photosensitive drum 11K is brought into contact with the intermediate transfer belt 20.

3A shows the contact state of the photosensitive drums 11Y, 11M, 11C, and 11K and the intermediate transfer belt 20 in the full color mode, and FIG. 3B shows the monochrome transfer mode. In the present embodiment, the retract roll 22 can be moved up and down, that is, the intermediate transfer belt 20 can be moved in the direction of urging and retracting from the inside, and the retract roll 22 as the retracting means can be moved. The photosensitive drums 11Y, 11M, and 11C and the intermediate transfer belt 20 can be brought into contact with and separated from each other according to the vertical movement. The primary transfer rolls 15 (specifically, 15Y, 15M, 15C, and 15K) provided in each image forming unit 10 are urged toward the intermediate transfer belt 20 by a spring (not shown). When 22 moves to a position away from the intermediate transfer belt 20, the primary transfer rolls 15Y, 15M, and 15C move away from the corresponding photosensitive drums 11Y, 11M, and 11C by the tension applied to the intermediate transfer belt 20. ing. Further, since the position of the idle roll 23 is fixed, for example, even if the retract roll 22 is moved up and down, the black photosensitive drum 11K and the intermediate transfer belt 20 are not separated.
In the image forming apparatus according to the present embodiment, the monochrome mode is set as a default, and is set to the state shown in FIG. 3B when the image forming apparatus is started or when the job ends. Yes.

  Next, an image forming process of the image forming apparatus according to the present embodiment will be described. Here, an image forming process in the full color image mode will be described. When a user turns on a start switch (not shown), a predetermined image forming process is executed. Specifically, for example, when this image forming apparatus is configured as a digital color copying machine, a document set on a document table (not shown) is read by a color image reading device (not shown), and the read signal is read as an image. It is converted into a digital image signal by signal processing, temporarily stored in a memory, and a toner image of each color is formed based on the stored digital image signals of four colors (Y, M, C, K). To.

  That is, the image forming units 10 (10Y, 10M, 10C, 10K) are driven based on the digital image signals of the respective colors obtained by the image signal processing. In each of the image forming units 10Y, 10M, 10C, and 10K, the laser exposure unit 13 writes an electrostatic latent image corresponding to the digital image signal on the photosensitive drum 11 that is uniformly charged by the charger 12. . Then, each formed electrostatic latent image is developed by a developing device 14 containing toner of each color to form a toner image of each color. In the case where the image forming apparatus is configured as a color printer, it is only necessary to generate toner images of respective colors based on image signals input from the outside.

The toner image formed on each photoconductor drum 11 is transferred from the photoconductor drum 11 by the primary transfer bias applied by the primary transfer roll 15 at the primary transfer position where each photoconductor drum 11 and the intermediate transfer belt 20 are in contact with each other. Primary transfer is performed on the surface of the intermediate transfer belt 20. Residual toner remaining on the photosensitive drum 11 after the primary transfer is removed by the drum cleaner 16.
The toner image primarily transferred to the intermediate transfer belt 20 in this way is superimposed on the intermediate transfer belt 20 and conveyed to the secondary transfer position as the intermediate transfer belt 20 rotates. On the other hand, the paper P is conveyed to the secondary transfer position of the secondary transfer device 30 at a predetermined timing, and the secondary transfer roll 31 nips the paper P against the intermediate transfer belt 20 (backup roll 27). The superimposed toner image carried on the intermediate transfer belt 20 is secondarily transferred onto the paper P by the action of a secondary transfer electric field formed between the secondary transfer roll 31 and the backup roll 27. Thereafter, the sheet P on which the toner image is transferred is conveyed to the fixing device 40 by the belt conveying device 74 and the like, and the toner image is fixed. On the other hand, residual toner and the like are removed from the intermediate transfer belt 20 after the secondary transfer by the belt cleaner 60. Further, toner or the like transferred from the intermediate transfer belt 20 to the secondary transfer roll 31 in the secondary transfer is removed by the roll cleaner 33.

  In this embodiment, the residue adhering to the surface of the photosensitive drum 11 after the primary transfer is scraped off by the cleaning blade 17 of the drum cleaner 16. Further, the residue adhering to the surface of the intermediate transfer belt 20 after the secondary transfer is scraped off by the cleaning blade 62 and the scraper 63 of the belt cleaner 60. Further, the residue adhering to the secondary transfer roll 31 after the secondary transfer is scraped off by the cleaning blade 35. This type of residue is mainly the above-mentioned residual toner, but also includes, for example, paper powder released from the paper P in addition to the residual toner. Among these, the residual toner forms a toner dam on the free end side of the cleaning blades 17, 35, 62 and assists in removing the toner. However, if paper dust larger than the residual toner is caught between the free ends of the cleaning blades 17, 35, 62, the residual toner will slip through, resulting in poor cleaning.

Therefore, in the present embodiment, paper dust or the like sandwiched between the cleaning blades 17, 35, 62 and the object to be cleaned (photosensitive drum 11, secondary transfer roll 31, intermediate transfer belt 20) at an appropriate timing. The paper dust removing operation to be removed is executed.
FIG. 4 is a block diagram showing a paper dust removal control unit 80 as paper dust removing means for executing the above-described paper dust removing operation. The paper dust removal control unit 80 constitutes a part of a control unit (not shown) that controls the entire image forming apparatus. The CPU 81 of the paper dust removal control unit 80 executes predetermined processing while appropriately exchanging data with the RAM 83 in accordance with a program stored in the ROM 82. The paper dust removal control unit 80 is connected to the image forming signal regarding the start and end of a job (JOB) or whether the image to be created is full color or black and white, and the total counted by the print number counter 91 via the input / output interface 84. The number of prints is entered. On the other hand, the paper dust removal control unit 80, via the input / output interface 84, drives a Y photosensitive drum drive motor 92 that drives the yellow photosensitive drum 11Y and an M photosensitive drum drive that drives the magenta photosensitive drum 11M. A motor 93, a C photosensitive drum driving motor 94 for driving the cyan photosensitive drum 11C, and a K photosensitive drum driving motor 95 for driving the black photosensitive drum 11K are controlled. Further, the paper dust removal control unit 80 further drives a retract roll up / down movement mechanism 96 that moves the retract roll 22 up and down, an intermediate transfer belt drive motor 97 that drives the drive roll 21 of the intermediate transfer belt 20, and the secondary transfer roll 31. A secondary transfer roll driving clutch 98 provided between a motor (not shown) is controlled.

Next, the paper dust removal process executed by the paper dust removal control unit 80 described above will be described with reference to the flowcharts shown in FIGS. First, processing for determining execution of paper dust removal shown in FIG. 5 will be described.
In this processing, first, it is determined whether or not an image forming operation has been started in the job (JOB), that is, the image forming apparatus (step 101). If the job has not been started, the process waits for the start in step 101. On the other hand, when the job is started, the above-described image forming operation is executed (step 102). Then, it is determined whether or not the value of the print number counter 91, that is, the number of prints has reached a predetermined specified number (for example, 1000) (step 103). If the number of prints has reached the specified number, a paper dust removal operation is executed (step 104), and then the count value of the print number counter 91 is reset (step 105). On the other hand, if the number of prints has not reached the specified number, the number of prints is added without executing the paper dust removal operation (step 106). Thereafter, it is determined whether or not the job is finished (step 107). Here, when the job is continuously executed, the process returns to step 102. On the other hand, if the job ends, a paper dust removal operation is executed (step 108), and the process ends.
As described above, in this embodiment, the paper dust removing operation is always executed at the end of the job, and the paper dust removing operation is executed every time the number of printed sheets reaches a predetermined number.

Next, processing in the paper dust removing operation shown in FIG. 6 will be described.
In this process, first, it is determined whether or not the image forming mode executed immediately before the paper dust removing operation is the full color mode (step 201). The immediately preceding image forming mode means the image forming mode in the job currently being executed in the case of step 104 shown in FIG. 5, and the image forming mode in the immediately preceding job in the case of step 108 shown in FIG. Means. If the previous image forming mode is the full color mode, the retract roll 22 is retracted (step 202), and the intermediate transfer belt 20 is separated from the yellow, magenta, and cyan photosensitive drums 11Y, 11M, and 11C. Let On the other hand, if the immediately preceding image forming mode is not the full color mode in step 201, in other words, if the immediately preceding image forming mode is the monochrome mode, the retract roll 22 has already been retracted, so the next step is continued. Proceed to 203.

  Next, the secondary transfer roll drive clutch 98 is turned off (step 203), so that the secondary transfer roll 31 can be freely rotated. Then, the rotation direction of the intermediate transfer belt drive motor 97 is switched to start the reverse drive of the intermediate transfer belt 20, and the black photoconductor drum 11K is started to rotate reversely by the K photoconductor drum drive motor 95 as the reverse rotation means. (Step 204). The reverse drive of the intermediate transfer belt 20 refers to rotating the intermediate transfer belt 20 in the direction opposite to the arrow B direction, and the reverse drive of the black photosensitive drum 11K refers to the black photosensitive drum 11K. A direction means to rotate in the reverse direction. Then, it is determined whether or not a predetermined time has elapsed since the start of reverse rotation of the intermediate transfer belt 20 and the black photosensitive drum 11K (step 205). Wait for the specified time. On the other hand, when the specified time has elapsed, the reverse rotation driving of the intermediate transfer belt 20 and the black photosensitive drum 11K is stopped (step 206). After that, it is determined whether or not this paper dust removal operation has interrupted the job being executed, in other words, whether or not it has been determined in step 104 (step 207). In step S208, the process returns to the image forming operation (step 208), and the process ends. On the other hand, if it is after the end of the image forming operation, the processing is ended as it is.

FIG. 7 shows a timing chart when the paper dust removing operation is executed after the image forming operation is executed. In this example, a case where a paper dust removing operation is performed after an image forming operation of a full-color image will be described.
When the image forming operation is started, the retract roll 22 urges the intermediate transfer belt 20 by the retract roll up-and-down moving mechanism 96, and the yellow, magenta, and cyan photosensitive drums 11Y, 11M, and 11C are pressed against the intermediate transfer belt 20. Let Then, yellow, magenta, cyan, and black photosensitive drums 11Y, 11M, and Y are driven by a Y photosensitive drum driving motor 92, an M photosensitive drum driving motor 93, a C photosensitive drum driving motor 94, and a K photosensitive drum driving motor 95, respectively. 11C and 11K are rotated (forward rotation) in the direction of arrow A shown in FIG. Further, the intermediate transfer belt drive motor 97 rotates (normally rotates) the intermediate transfer belt 20 in the direction of the arrow B shown in FIG. 1, and the secondary transfer roll drive clutch 98 is inserted, whereby the secondary transfer roll 31 is driven by a drive motor (not shown). Also rotate forward. In this state, the image forming operation described above is executed.

  Next, when the image forming operation is completed, the yellow photoconductor drum drive motor 92, the M photoconductor drum drive motor 93, the C photoconductor drum drive motor 94, and the K photoconductor drum drive motor 95 are stopped by driving. The rotation of the magenta, cyan, and black photoconductive drums 11Y, 11M, 11C, and 11K is stopped. Further, the rotation of the intermediate transfer belt 20 is stopped by stopping the driving by the intermediate transfer belt drive motor 97. Furthermore, the rotation of the secondary transfer roll 31 is stopped by stopping the drive by a drive motor (not shown). Furthermore, the secondary transfer roll drive clutch 98 is disengaged, and the secondary transfer roll 31 is in a state where it can freely rotate. Then, the retract roll 22 is moved in the retracting direction by the retract roll up-and-down moving mechanism 96 to separate the yellow, magenta, and cyan photosensitive drums 11Y, 11M, and 11C from the intermediate transfer belt 20.

Thereafter, the black photosensitive drum 11K is rotated (reversed) in the direction opposite to the arrow A direction shown in FIG. 1 by the K photosensitive drum drive motor 95, and the intermediate transfer belt 20 is moved to the state shown in FIG. Rotate (reverse) in the direction opposite to the direction of arrow B shown. At this time, as described above, the secondary transfer roll 31 is in a state in which the secondary transfer roll drive clutch 98 is disengaged and can freely rotate, and maintains a contact state with the intermediate transfer belt 20. Therefore, the intermediate transfer belt 20 that rotates in the reverse direction rotates (reverses) in the reverse direction to that during image formation. At this time, the reverse rotation speed of the black photosensitive drum 11K and the reverse rotation speed of the intermediate transfer belt 20 are different. The reason will be described later.
As the intermediate transfer belt 20 rotates in the reverse direction in this way, foreign matters such as paper dust sandwiched between the intermediate transfer belt 20 and the cleaning blade 62 are drawn out to the upstream side of the opposing portions and removed. . On the other hand, when the secondary transfer roll 31 rotates in reverse with the intermediate transfer belt 20, foreign matters such as paper dust sandwiched between the secondary transfer roll 31 and the cleaning blade 35 are placed on the opposing portions of both. Pulled upstream and removed. Further, since the yellow, magenta, and cyan photosensitive drums 11Y, 11M, and 11C are separated from the intermediate transfer belt 20, problems such as scratches do not occur even if they are not reversely rotated. Further, since the black photosensitive drum 11K is rotated in the reverse direction like the intermediate transfer belt 20, problems such as scratches are unlikely to occur.

  Then, after the predetermined time has elapsed, the driving of the black photosensitive drum 11K is stopped by stopping the driving by the K photosensitive drum driving motor 95, and the driving by the intermediate transfer belt driving motor 97 is stopped. As a result, the rotation of the intermediate transfer belt 20 is stopped. Further, when the rotation of the intermediate transfer belt 20 is stopped, the rotation of the secondary transfer roll 31 is also stopped.

Here, the reason why the reverse rotation speed of the black photosensitive drum 11K and the reverse rotation speed of the intermediate transfer belt 20 are different in the above-described paper dust removing operation will be described.
In the present embodiment, the distance between the cleaning blade 62 and the seal 65 in the belt cleaner 60 shown in FIG. 1 is about 20 mm, and the distance between the cleaning blade 17 and the seal 19 in the drum cleaner 16 shown in FIG. Each is set to about 15 mm. When the black photosensitive drum 11K is rotated in the direction opposite to the arrow A direction, the toner dam adhering to the free end side of the cleaning blade 17 moves toward the seal 19 side by the movement of the photosensitive drum 11K. Overcoming the seal 19 causes toner scattering, which is not preferable. On the other hand, when the intermediate transfer belt 20 is rotated in the direction opposite to the arrow B direction, similarly, the toner dam adhering to the free end side of the cleaning blade 62 moves toward the seal 65 side by the movement of the intermediate transfer belt 20. However, overcoming the seal 65 causes toner scattering, which is not preferable.

  Therefore, in this embodiment, the reverse rotation amount of the black photosensitive drum 11K is set so that the toner dam detached from the cleaning blade 17 does not get over the seal 19, and the toner dam detached from the cleaning blade 62 sets the seal 65. The reverse rotation amount of the intermediate transfer belt 20 is set so as not to get over. The reverse rotation speed of the black photosensitive drum 11K is slightly slower than the reverse rotation speed of the intermediate transfer belt 20 in order to allow different reverse amounts (distances) to be moved in the same time. The black photosensitive drum 11K and the intermediate transfer belt 20 have different reverse rotational speeds, so that a slight slip occurs at the contact portion between the black photosensitive drum 11K and the intermediate transfer belt 20, but the black photosensitive drum The body drum 11K is larger in diameter than the yellow, magenta, and cyan photoconductor drums 11Y, 11M, and 11C, so that the body drum 11K is less likely to be damaged and is not particularly problematic.

  As described above, in the present embodiment, the paper sandwiched between the intermediate transfer belt 20 and the cleaning blade 62 by rotating the secondary transfer roll 31 in reverse with the reverse rotation of the intermediate transfer belt 20. Foreign matter such as powder and foreign matter such as paper dust sandwiched between the secondary transfer roll 31 and the cleaning blade 35 can be removed together. At that time, the drive of the secondary transfer roll 31 is released so that the secondary transfer roll 31 can freely rotate, and when the intermediate transfer belt 20 is rotated in the reverse direction, the secondary transfer roll 31 is also rotated in the reverse direction by the follower. As a result, the configuration becomes simple, and the increase in size and complexity of the apparatus can be suppressed.

Further, in the present embodiment, when the intermediate transfer belt 20 is rotated in the reverse direction, the yellow, magenta, and cyan photosensitive drums 11Y, 11M, and 11C are separated from the intermediate transfer belt 20 in advance. The photosensitive drums 11Y, 11M, and 11C can be prevented from being damaged. Further, since the black photosensitive drum 11K is reversely rotated in conjunction with the reverse rotation of the intermediate transfer belt 20, the black photosensitive drum 11K can be prevented from being damaged. Here, when the black photosensitive drum 11K is reversely rotated, the toner dam (residual toner) separated from the cleaning blade 17 gets over the seal 19 by setting the speed different from the reverse rotation speed of the intermediate transfer belt 20. It is possible to prevent a situation such as flying into the aircraft.
In this embodiment, the paper dust removing operation, that is, the reverse rotation of the intermediate transfer belt 20 and the like is executed after the image forming operation is completed and every predetermined number of prints. It is possible to suppress the occurrence of poor cleaning due to, and obtain a clean image.

  In the present embodiment, a so-called tandem image forming apparatus has been described as an example. However, the present invention is not limited to this. For example, every time the intermediate transfer belt makes one round, yellow, magenta, cyan, black The present invention can be similarly applied to a so-called four-cycle type image forming apparatus in which a full-color toner image is formed by superimposing and transferring the toner image, and then the full-color toner image is collectively transferred to a sheet.

1 is a diagram illustrating an image forming apparatus to which the exemplary embodiment is applied. It is a figure which shows the structure of an image forming unit. (a) is a diagram showing a contact state of each photosensitive drum and the intermediate transfer belt in a full color mode, and (b) is a black and white mode. It is a block diagram which shows the paper dust removal control part which performs paper dust removal operation | movement. It is a flowchart which shows the flow of the process which determines execution of paper dust removal. It is a flowchart which shows the flow of the process in paper dust removal operation | movement. It is a timing chart which shows operation | movement of each component in paper dust removal operation | movement.

Explanation of symbols

10 (10Y, 10M, 10C, 10K) ... Image forming unit, 11 (11Y, 11M, 11C, 11K) ... Photoconductor drum, 12 ... Charger, 13 ... Laser exposure unit, 14 ... Developer, 15 (15Y, 15M, 15C, 15K) ... primary transfer roll, 16 ... drum cleaner, 17 ... cleaning blade, 18 ... drum cleaner housing, 19 ... seal, 20 ... intermediate transfer belt, 21 ... drive roll, 22 ... retract roll, 23 ... idle Roll, 24 ... Sensor roll, 25 ... Tension roll, 26 ... Pre-roll, 27 ... Backup roll, 28 ... Brush facing roll, 29 ... Blade facing roll, 30 ... Secondary transfer device, 31 ... Secondary transfer roll, 32 ... Power feeding Roll, 33 ... Roll cleaner, 34 ... Cleaning brush, 35 ... Cleaning blade, 36 ... Block 37 ... flicker bar, 40 ... fixing device, 60 ... belt cleaner, 61 ... cleaning brush, 62 ... cleaning blade 63 ... scraper, 64 ... belt cleaner housing, 65 ... seal

Claims (8)

An image carrier on which a toner image is formed and carried rotatably;
An intermediate transfer body on which the toner image carried rotatably and carried on the image carrier is primarily transferred;
A secondary transfer member that is disposed in pressure contact with the intermediate transfer member and secondarily transfers the toner image that has been primarily transferred to the intermediate transfer member to a recording material;
First cleaning means for cleaning the intermediate transfer member after secondary transfer;
A second cleaning means for cleaning the secondary transfer member after the secondary transfer;
In an image forming operation for forming an image on the recording material, the intermediate transfer member is driven and rotated in a first direction to remove paper dust in the first cleaning unit and the second cleaning unit. In the paper dust removing operation, driving means for driving the intermediate transfer member to rotate in the second direction opposite to the image forming operation;
In the image forming operation, the driving unit and the secondary transfer member are connected and the driving force of the driving unit is transmitted to the secondary transfer member, whereby the secondary transfer member and the intermediate transfer member are transferred. In the paper dust removing operation, the connection between the driving unit and the secondary transfer member is interrupted and the driving unit is transferred to the secondary transfer member. An image forming apparatus comprising: an intermittent unit that releases the transmission of the driving force to cause the secondary transfer member to follow the intermediate transfer member and rotate in the same direction as the second direction at the press contact portion . It said first cleaning means includes the intermediate transfer member wherein the first blade is pressed disposed counter direction against the direction of,
The image forming apparatus according to claim 1, wherein the second cleaning unit includes a blade press-contacted in a counter direction with respect to a rotation direction of the secondary transfer member in the image forming operation . A third cleaning means for cleaning the image carrier after the primary transfer;
The image forming apparatus according to claim 1, further comprising a reverse rotation unit configured to rotate the image carrier in the reverse direction in conjunction with the rotation of the intermediate transfer body in the second direction . The first cleaning unit is configured to come into contact with the intermediate transfer member on the upstream side of the blade in the first direction with a blade press-contacted in the counter direction with respect to the first direction of the intermediate transfer member. And a sealing member disposed in the
The third cleaning unit includes another blade arranged in pressure contact with the rotational direction of the image carrier in the image forming operation, and the rotational direction of the image carrier in the image forming operation. Another seal member arranged to contact the image carrier upstream of the other blade,
When the distance between the blade and the seal member is greater than the distance between the other blade and the other seal member, the reverse rotation speed of the intermediate transfer member is set to the reverse of the image carrier. The image forming apparatus according to claim 3 , wherein the image forming apparatus is faster than the rotation speed . A yellow image carrier that forms and supports a yellow toner image, a magenta image carrier that forms and supports a magenta toner image, a cyan image carrier that forms and supports a cyan toner image, and a black toner image that is formed and supported A tandem type image forming apparatus that primarily transfers a toner image formed by a black image carrier to an intermediate transfer member, and secondarily transfers the toner image primarily transferred to the intermediate transfer member to a recording material,
Said pressed against disposed intermediate transfer body, a secondary transfer member is secondarily transferred to the recording material the toner image primarily transferred to the intermediate transfer member,
An intermediate transfer cleaning means for cleaning the intermediate transfer body after the secondary transfer; a secondary transfer cleaning means for cleaning the secondary transfer member after the secondary transfer ;
In an image forming operation for forming an image on the recording material, the intermediate transfer member is driven and rotated in a first direction to remove paper dust on the intermediate transfer cleaning unit and the secondary transfer cleaning unit. In the powder removal operation, a driving unit that drives the intermediate transfer member to rotate in the second direction opposite to the image forming operation;
In the image forming operation, the driving unit and the secondary transfer member are connected and the driving force of the driving unit is transmitted to the secondary transfer member, whereby the secondary transfer member and the intermediate transfer member are transferred. In the paper dust removing operation, the connection between the driving unit and the secondary transfer member is interrupted and the driving unit is transferred to the secondary transfer member. The intermittent transfer means for causing the secondary transfer member to follow the intermediate transfer member and to rotate in the same direction as the second direction at the pressure contact portion by releasing the transmission of the driving force of
In the paper dust removal operation, the yellow image carrier, the magenta image carrier, and the cyan image carrier are separated from the intermediate transfer member while the black image carrier is in contact with the intermediate transfer member. An image forming apparatus including a separating unit . An image carrier cleaning means for cleaning the image carrier after the primary transfer ;
6. The image forming apparatus according to claim 5 , further comprising reverse rotation means for rotating the black image carrier in contact with the intermediate transfer member in the reverse direction in the paper dust removing operation . The intermediate transfer cleaning unit is configured to be in contact with the intermediate transfer member on the upstream side of the blade in the first direction with a blade disposed in pressure contact with the first direction of the intermediate transfer member. Having a sealing member disposed,
The image carrier cleaning means includes another blade arranged in pressure contact with the rotation direction of the image carrier in contact with the intermediate transfer member in the image forming operation, and the blade in the image forming operation. Another seal member arranged to contact the image carrier upstream of the other blade in the rotation direction of the image carrier;
When the distance between the blade and the seal member is greater than the distance between the other blade and the other seal member, the reverse rotation speed of the intermediate transfer member is set to the reverse of the image carrier. The image forming apparatus according to claim 6 , wherein the image forming apparatus is faster than a rotational speed . The intermediate transfer cleaning unit includes a first blade which is pressed against arranged in the counter direction against the direction of the intermediate transfer member,
The image forming apparatus according to claim 5 , wherein the secondary transfer cleaning unit includes a blade press-contacted in a counter direction with respect to a rotation direction of the secondary transfer member in the image forming operation .

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