Image forming apparatus

Abstract

To reduce the possibility that, in removing an intermediate transfer unit from an apparatus body, an operator and an installation environment of an image forming apparatus become dirty due to an attachment remaining on the intermediate transfer belt.SOLUTION: An image forming apparatus has: image carriers; a toner image forming section; an intermediate transfer belt stretched by a plurality of stretch rollers; a cleaning device for the intermediate transfer belt; a belt driving section; a control section; and an input section inputting an instruction based on an operation made by an operator to the control section. A unit comprising the intermediate transfer belt and the plurality of stretch rollers is removably attached to an apparatus body. When the unit is removed from the apparatus body, according to the instruction from the input section, prior to the removal and after the last image formation before the removal, the control section can control the belt driving section to execute a belt cleaning operation of driving to rotate the intermediate transfer belt and causing the cleaning device to clean the surface of the intermediate transfer belt.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having a combination of the functions of these machines, which uses an electrophotographic or electrostatic recording system. [Background technology]

[0002] Conventionally, as an image forming apparatus such as a copying machine using an electrophotographic method, there is an intermediate transfer method in which a toner image formed on an image carrier is primarily transferred from the image carrier to an intermediate transfer body, and then the toner image is secondarily transferred from the intermediate transfer body to a recording material. As the image carrier, a photosensitive drum, which is a drum-shaped photosensitive body, is often used. Also, as the intermediate transfer body, an intermediate transfer belt, which is an endless belt stretched around a plurality of tension rollers, is often used.

[0003] In such an image forming apparatus, the intermediate transfer belt may be subject to fatigue damage due to changes over time or long-term operation, and therefore it is desirable to replace the intermediate transfer belt periodically, for example, depending on the amount of use. In view of this, there is a configuration in which the intermediate transfer belt is integrated into a unit together with a plurality of tension rollers and a belt cleaning device that cleans the intermediate transfer belt, and this unit (intermediate transfer unit) is detachable from the main body of the image forming apparatus (hereinafter, also simply referred to as the "main body") (for example, Patent Document 1). By making the intermediate transfer belt detachable from the main body as an intermediate transfer unit, it is possible to easily replace the intermediate transfer belt. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-191584 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, for example, when an operator removes the intermediate transfer unit from the apparatus body, there may be residual matter such as toner or paper powder remaining on the intermediate transfer belt. In such a case, there is a possibility that the operator or the installation environment of the image forming apparatus may be soiled. Therefore, it is desirable to suppress the occurrence of such soiling. Conventionally, the intermediate transfer unit has generally been attached to and detached from the apparatus body by a maintenance worker, but when this is made possible for the user to easily maintain the image forming apparatus, it becomes even more important to suppress the occurrence of the above-mentioned soiling.

[0006] Therefore, an object of the present invention is to reduce the possibility of an operator or the installation environment of an image forming apparatus becoming dirty due to deposits remaining on the intermediate transfer belt when the intermediate transfer unit is removed from the apparatus main body. [Means for solving the problem]

[0007] The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides an image forming apparatus including an image carrier that carries a toner image, a toner image forming section that forms a toner image on the surface of the image carrier, a rotatable intermediate transfer belt that is stretched around a plurality of tension rollers and contacts the image carrier to form a transfer section, the toner image being transferred from the image carrier in the transfer section, a cleaning device that removes toner from the surface of the intermediate transfer belt in a cleaning section, a belt drive section that drives and rotates the intermediate transfer belt, a control section that can control the belt drive section, and an input section that inputs instructions based on operations by an operator to the control section, and the toner image transferred from the image carrier to the intermediate transfer belt is transferred to the intermediate transfer belt by a toner image forming section that forms a toner image on the surface of the image carrier. This is an image forming apparatus that performs image formation by transferring an image from a transfer belt to a recording material, wherein a unit having the intermediate transfer belt and the multiple tension rollers is detachable from the main body of the image forming apparatus, and the control unit is capable of controlling the belt drive unit, in response to instructions from the input unit, when the unit is removed from the main body of the apparatus, to perform a belt cleaning operation in which the intermediate transfer belt is rotated and the cleaning device cleans the surface of the intermediate transfer belt after the last image formation before the removal and prior to the removal, in accordance with instructions from the input unit.

[0008] According to another aspect of the present invention, there is provided a cleaning device comprising: an image carrier that carries a toner image; a toner image forming unit that forms a toner image on a surface of the image carrier; a rotatable intermediate transfer belt that is stretched around a plurality of tension rollers and contacts the image carrier to form a transfer unit, the toner image being transferred from the image carrier at the transfer unit; and a cleaning device that removes toner from the surface of the intermediate transfer belt at a cleaning unit, the cleaning device comprising: a cleaning member that removes toner from the surface of the intermediate transfer belt; a cleaning container that contains the toner removed from the surface of the intermediate transfer belt; and a transport member that transports the toner in the cleaning container to be discharged outside the cleaning container; and a cleaning device that drives the transport member. An image forming apparatus is provided which has a drive unit, a storage unit which stores toner discharged from the cleaning container, and a control unit capable of controlling the cleaning drive unit, and which performs image formation by transferring a toner image transferred from the image carrier to the intermediate transfer belt, and then from the intermediate transfer belt to a recording material, wherein the cleaning device is detachable from the main body of the image forming apparatus, and the control unit is capable of controlling the cleaning drive unit to perform a toner discharge operation, which drives the conveying member to discharge toner from the cleaning container after the last image formation before the removal, and prior to the removal, when the cleaning device is removed from the main body of the apparatus. Effect of the Invention

[0009] According to the present invention, it is possible to reduce the possibility that an operator or the installation environment of the image forming apparatus will become soiled due to deposits remaining on the intermediate transfer belt when the intermediate transfer unit is removed from the apparatus main body. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Diagram 2] FIG. 2 is a schematic cross-sectional view of an image forming unit. [Diagram 3] FIG. 2 is a schematic perspective view of an intermediate transfer unit. [Figure 4] FIG. 2 is a schematic cross-sectional view for explaining a stretching form of an intermediate transfer belt. [Diagram 5] 4 is a schematic perspective view showing a drive connection portion between a belt conveying portion and a belt cleaning device in the intermediate transfer unit; FIG. [Figure 6] FIG. 2 is a schematic diagram for explaining a configuration of a belt cleaning device. [Figure 7] FIG. 2 is a schematic perspective view for explaining an attachment / detachment operation of the intermediate transfer unit to / from the main body of the apparatus. [Figure 8] FIG. 2 is a schematic block diagram for explaining a control configuration of the image forming apparatus. [Figure 9] 5 is a schematic diagram for explaining toner remaining on the surface of the intermediate transfer belt. FIG. [Figure 10] FIG. 11 is a flowchart illustrating an example of a procedure for replacing an intermediate transfer unit. [Figure 11] FIG. 13 is a schematic diagram showing an example of a display screen related to a cleaning mode. [Figure 12] FIG. 11 is a timing chart of the operation in the cleaning mode. [Figure 13] FIG. 11 is a timing chart of another example of the operation in the cleaning mode. [Figure 14] 13 is a schematic diagram showing a belt conveying section and a belt cleaning device according to another example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[0012] [Example 1] 1. Overall configuration of image forming device 1 is a schematic cross-sectional view of an image forming apparatus 1 according to this embodiment. The image forming apparatus 1 according to this embodiment is a tandem-type full-color image forming apparatus (a multifunction machine having the functions of a copier, printer, and fax) that employs an intermediate transfer system and is capable of forming a full-color image on a sheet-shaped recording material S using an electrophotographic system.

[0013] In addition, with respect to the image forming apparatus 1 and its elements, the front side of the paper in FIG. 1 is referred to as the "front side (front side)" and the back side of the paper is referred to as the "rear side (back side)". The front-rear direction connecting the "front side" and the "rear side" is approximately parallel to the rotation axis direction of the photosensitive drum 3 and the tension roller of the intermediate transfer belt 111 described later. In addition, with respect to the image forming apparatus 1 and its elements, the left side when viewed from the front side is referred to as the "left side" and the right side is referred to as the "right side". In addition, with respect to the image forming apparatus 1 and its elements, the up-down direction refers to the up-down direction in the direction of gravity (vertical direction), but does not mean only directly above and directly below, but also includes the upper side and the lower side of a horizontal plane passing through a target element or position. In addition, with respect to the rotating members provided in the image forming apparatus 1, the rotation in the direction when rotating during image formation is referred to as the "forward rotation", and the rotation in the opposite direction is referred to as the "reverse rotation".

[0014] The image forming apparatus 1 has a plurality of image forming units, i.e., image forming units Pa, Pb, Pc, and Pd, which form toner images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. Elements having the same or corresponding functions or configurations provided for each color may be generally described by omitting the suffixes a, b, c, and d indicating that the element is for one of the colors. In this embodiment, the image forming unit P is configured to include a photosensitive drum 3, a charging roller 4, an exposure device 7, a developing device 5, and a drum cleaning device 6, which will be described later. FIG. 2 is a schematic cross-sectional view showing one representative image forming unit P.

[0015] The photosensitive drum 3, which is a rotatable drum-type (cylindrical) photosensitive member (electrophotographic photosensitive member), is rotated in a clockwise direction (positive rotation direction) indicated by an arrow R1 in FIG. 2 during image formation. The surface of the rotating photosensitive drum 3 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by a charging roller 4, which is a roller-type charging member serving as a charging means. The charging roller 4 constitutes a charging device that charges the photosensitive drum 3. During charging, a predetermined charging voltage (charging bias) of the same polarity as the charging polarity (negative polarity in this embodiment) of the photosensitive drum 3 is applied to the charging roller 4 by a charging power source E1 serving as a charging voltage application means (charging voltage application section). The surface of the charged photosensitive drum 3 is scanned and exposed by an exposure device (laser scanner) 7 serving as an exposure means in accordance with an image signal (image information), and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 3. The exposure device 7 of each image forming station P receives image signals for yellow, magenta, cyan, and black, respectively, and irradiates the surface of each photosensitive drum 3 with laser light in accordance with these image signals, neutralizing the charge on the photosensitive drum 3 and forming an electrostatic latent image on the photosensitive drum 3.

[0016] The electrostatic latent image formed on the photosensitive drum 3 is developed (visualized) by supplying toner by the developing device 5 as a developing means, and a toner image (toner image, developer image) is formed on the photosensitive drum 3. In this embodiment, the developing device 5 uses a two-component developer including toner (non-magnetic toner particles) and carrier (magnetic carrier particles) as the developer. The developing device 5 has a developing container 51 that contains the developer, and a developing sleeve 52 as a developing member (developer carrier) that carries the developer and transports it to the portion facing the photosensitive drum 3 (developing portion). The developing sleeve 52 is disposed with a predetermined gap between it and the photosensitive drum 3. The developing device 5 for each color is replenished with a refill developer (including toner and carrier in this embodiment) from the toner bottle 20 for each color. During development, a predetermined developing voltage (developing bias) of the same polarity as the charging polarity (negative polarity in this embodiment) of the photosensitive drum 3 is applied to the developing sleeve 52 by a developing power source E2 as a developing voltage application means (developing voltage application portion). In this embodiment, toner charged with the same polarity as the charge polarity of the photosensitive drum 3 (negative polarity in this embodiment) adheres to the exposed portion (image portion) on the photosensitive drum 3, which has been uniformly charged and then exposed to light to reduce the absolute value of the potential (reverse development method). In this embodiment, the normal charge polarity of the toner, which is the main charge polarity of the toner during development, is negative polarity. In this embodiment, the charging roller 4, exposure device 7, developing device 5, etc. constitute a toner image forming portion that forms a toner image on the photosensitive drum 3.

[0017] An intermediate transfer belt 111, which is a rotatable endless belt serving as an intermediate transfer body, is disposed so as to face the four photosensitive drums 3. The intermediate transfer belt 111 is tensioned by a drive roller 112, a tension roller 113, and an idler roller 115 serving as a plurality of tension rollers (support rollers). The intermediate transfer belt 111 receives a driving force as the drive roller 112 is driven to rotate, and rotates (moves around) in a counterclockwise direction (positive rotation direction) indicated by an arrow R2 in FIG. 1 and FIG. 2. Primary transfer rollers 114a, 114b, 114c, and 114d, which are roller-type primary transfer members serving as primary transfer means, are disposed on the inner peripheral surface side of the intermediate transfer belt 111, corresponding to the photosensitive drums 3a, 3b, 3c, and 3d. The tension rollers other than the drive roller 112 and each primary transfer roller 114 are driven to rotate with the rotation of the intermediate transfer belt 111. The primary transfer roller 114 presses the intermediate transfer belt 111 against the photosensitive drum 3, forming a primary transfer portion N1 which is a contact portion between the photosensitive drum 3 and the intermediate transfer belt 111. The toner image formed on the photosensitive drum 3 is transferred (primary transfer) onto the rotating intermediate transfer belt 111 by the action of the primary transfer roller 114 at the primary transfer portion N1. During the primary transfer, a primary transfer voltage (primary transfer bias) which is a DC voltage of the opposite polarity (positive polarity in this embodiment) to the normal charging polarity of the toner is applied to the primary transfer roller 114 by a primary transfer power source E3 as a primary transfer voltage application means (primary transfer voltage application portion). For example, when a full-color image is formed, the toner images of each color of yellow, magenta, cyan, and black formed on each photosensitive drum 3 are transferred onto the intermediate transfer belt 111 in a manner to be superimposed in sequence at each primary transfer portion N1.

[0018] On the outer peripheral surface side of the intermediate transfer belt 111, a secondary transfer outer roller 8 is disposed at a position facing the driving roller 112 with the intermediate transfer belt 111 sandwiched therebetween. In this embodiment, the driving roller 112 also functions as a secondary transfer inner roller, which is a roller-type secondary transfer member as a secondary transfer means. In this embodiment, the secondary transfer outer roller 8 also functions as a secondary transfer opposing roller, which is an opposing member (opposing electrode) of the driving roller 112. The secondary transfer outer roller 8 is pressed against the driving roller 112 via the intermediate transfer belt 111, forming a secondary transfer portion N2, which is a contact portion between the intermediate transfer belt 111 and the secondary transfer outer roller 8. A predetermined pressure force and an electrostatic load bias are applied to the toner image formed on the intermediate transfer belt 111 at the secondary transfer portion N2. As a result, the toner image on the intermediate transfer belt 111 is transferred (secondarily transferred) onto the recording material (transfer material, recording medium, sheet) S that is being conveyed while being sandwiched between the intermediate transfer belt 111 and the secondary transfer outer roller 8. During the secondary transfer, a secondary transfer voltage (secondary transfer bias), which is a DC voltage of the same polarity (negative in this embodiment) as the normal charging polarity of the toner, is applied to the drive roller 112 by a secondary transfer power source E4 (FIG. 8) serving as a secondary transfer voltage application means (secondary transfer voltage application unit). The secondary transfer outer roller 8 is electrically grounded. Note that a secondary transfer voltage may be applied to a secondary transfer outer roller serving as a secondary transfer member corresponding to the secondary transfer outer roller 8 in this embodiment, and a secondary transfer inner roller serving as an opposing member corresponding to the drive roller 112 in this embodiment may be electrically grounded. In that case, during the secondary transfer, a secondary transfer voltage of the opposite polarity to the normal charging polarity of the toner is applied to the secondary transfer outer roller.

[0019] A recording material S such as paper is stored inside a cassette 9 serving as a feeding section, or is stacked on a manual feed tray 10 serving as a feeding section. The recording materials S in the cassette 9 or on the manual feed tray 10 are fed out one by one, starting from the top, by a feeding roller 11 serving as a feeding member, and are transported to a pair of registration rollers 12 serving as a transport member. The recording materials S are transported to the secondary transfer section N2 by the pair of registration rollers 12 at a predetermined timing in accordance with the toner on the intermediate transfer belt 111 being transported to the secondary transfer section N2.

[0020] The recording material S onto which the toner image has been transferred is conveyed to a fixing device 13 serving as a fixing means. The fixing device 13 heats and presses the recording material S carrying the unfixed toner image with a pair of fixing rollers, thereby fixing (melting and bonding) the toner image onto the recording material S. The recording material S onto which the toner image has been fixed is discharged (output) onto a discharge tray 14 serving as a discharge section provided outside the device body 2 of the image forming apparatus 1, by a pair of discharge rollers 21 serving as a discharge member or the like.

[0021] In addition, the toner remaining on the photosensitive drum 3 after the primary transfer (primary transfer residual toner) is removed from the photosensitive drum 3 and collected by a drum cleaning device 6 serving as a photosensitive body cleaning means. The drum cleaning device 6 is configured to have a cleaning container 61, a cleaning blade 62 serving as a cleaning member arranged in contact with the surface of the photosensitive drum 3, and a conveying screw 63 serving as a collected toner conveying member. The drum cleaning device 6 scrapes off the primary transfer residual toner from the surface (outer peripheral surface) of the rotating photosensitive drum 3 by the cleaning blade 62, and stores it in the cleaning container 61. The collected matter such as the toner collected by the drum cleaning device 6 is conveyed by the conveying screw 63 and discharged from the cleaning container 61, and is conveyed to the waste toner container 22 via a waste toner conveying path. In addition, a belt cleaning device 150 serving as an intermediate transfer body cleaning means is arranged on the outer peripheral surface side of the intermediate transfer belt 111. The belt cleaning device 150 is located downstream of the secondary transfer portion N2 and upstream of the primary transfer portion N1 (the most upstream primary transfer portion N1a) in the forward rotation direction of the intermediate transfer belt 111. In this embodiment, the belt cleaning device 150 is disposed at a position facing the tension roller 113 with the intermediate transfer belt 111 in between. The toner (secondary transfer residual toner) remaining on the intermediate transfer belt 111 after the secondary transfer and the adhering materials such as paper powder are removed from the intermediate transfer belt 111 and collected by the belt cleaning device 150. The collected materials such as the toner collected by the belt cleaning device 150 are transported to the waste toner container 22 via a waste toner transport path. The belt cleaning device 150 will be described in further detail later.

[0022] Incidentally, the collected material collected by the drum cleaning device 6 and the belt cleaning device 150 generally contains not only toner but also paper powder, toner external additives, and the like, and may also contain carriers. However, here, the collected material may simply be referred to as "toner (or collected toner)." In addition, although transfer residual toner is mainly used as an example of the residual toner remaining on the photosensitive drum 3 or the intermediate transfer belt 111, the residual toner is not limited to transfer residual toner. Residual toner may also be a test image (control image, patch) that is formed on the photosensitive drum 3 or the intermediate transfer belt 111 and is not transferred to the transfer target.

[0023] In this embodiment, in each image forming section P, the photosensitive drum 3 and the charging roller 4, developing device 5 and drum cleaning device 6 acting on it as process means integrally constitute a process cartridge 23 that is detachably attached to the main body 2 of the apparatus.

[0024] In this embodiment, the intermediate transfer belt 111, the multiple tension rollers 112, 113, 115, the primary transfer rollers 114, the belt cleaning device 150, etc., integrally constitute an intermediate transfer unit (intermediate transfer device) 100 that is detachable from the apparatus main body 2. The intermediate transfer unit 100 will be described in further detail later.

[0025] The waste toner container 22 is detachable from the apparatus main body 2, and when it becomes full of collected toner, it is replaced with an empty waste toner container 22.

[0026] In this embodiment, the apparatus main body 2 corresponds to a configuration of the image forming apparatus 1 excluding the process cartridges 23, the intermediate transfer unit 100, and the waste toner container 22.

[0027] In this embodiment, the intermediate transfer unit 100 is detachably disposed at a vertically middle position in the apparatus main body 2. In this embodiment, four image forming sections P that form images on the intermediate transfer belt 111 are disposed below the intermediate transfer unit 100 from the upstream side to the downstream side along the moving direction of the image transfer surface of the intermediate transfer belt 111. In this embodiment, the arrangement direction of the four image forming sections P (photosensitive drums 3) is approximately horizontal. That is, in this embodiment, the common tangent plane of the four photosensitive drums 3 on the side that contacts the intermediate transfer belt 111 is approximately horizontal. In this embodiment, the exposure device 7 is disposed below the photosensitive drum 3. In this embodiment, a drive unit 130 (FIG. 8) is disposed at the rear side in the apparatus main body 2 as a drive means for driving the photosensitive drum 3 (and the conveying screw 63 of the drum cleaning device 61), the developing device 5, the intermediate transfer belt 111 (and the conveying screw 153 of the belt cleaning device 150 described later), and the like. The drive unit 130 will be described in more detail later.

[0028] The image forming apparatus 1 is also provided with an operation unit 200. In this embodiment, the operation unit 200 is disposed at the front upper portion of the apparatus main body 2. The operation unit 200 is attached to the apparatus main body 2 so as to be capable of communicating with a control unit 140 (FIG. 8) provided in the apparatus main body 2. The operation unit 200 has keys as an input unit that can input information to the control unit 140 by an operation by an operator such as a user or a maintenance worker. The operation unit 200 also has a display screen (display panel) using a liquid crystal panel as a display unit that can display information to the operator under the control of the control unit 140. In this embodiment, the operation unit 200 is configured to have a touch panel (operation display unit) having the functions of an input unit and a display unit. The operation unit 200 is configured to display information necessary for the operator to operate the image forming apparatus 1, such as the remaining amount of consumables such as the recording material S and toner supplied to the image forming apparatus 1, a warning message when the consumables run out, and a procedure for supplying the consumables. The operation unit 200 also receives input of information from an operator, such as the size and basis weight of the recording material S, image density adjustment, and setting of the number of copies to be output.

[0029] The image forming apparatus 1 can execute a job (print job) in response to an instruction from the operation unit 200 or an external device 500 (FIG. 8) such as a personal computer (host device) communicably connected to the image forming apparatus 1. For example, when the image forming apparatus 1 functions as a copier, it executes an image forming operation based on image information of an original read by an original reading unit (not shown) provided in the image forming apparatus 1 in response to an instruction from the operation unit 200. Also, for example, when the image forming apparatus 1 functions as a printer, it executes an image forming operation based on image information sent from the external device 500 in response to an instruction from the external device 500.

[0030] A job is a series of operations that starts with a start instruction and forms an image on one or more recording materials S with toner based on image information and outputs the image. A job generally consists of a pre-rotation process, which is a preparation operation before image formation, an image formation process, which forms an image to be transferred to the recording material S and output, a paper-interval process, which is an operation between recording materials S during continuous image formation on multiple recording materials S, and a post-rotation process, which is an arrangement operation after image formation. The period of the image formation process corresponds to the image formation time, and the period other than the image formation time (the pre-rotation process, paper-interval process, and post-rotation process, standby state, sleep state, etc.) corresponds to the non-image formation time. For example, when the image formation process on the last recording material S in a job is completed and the recording material S is discharged from the device main body 2, the image forming device 1 executes the post-rotation process. The post-rotation process is a process in which, even after the image formation process is completed, a predetermined process device such as the intermediate transfer belt 111 and the photosensitive drum 3 is operated to prepare for the next job.

[0031] 2. Intermediate transfer unit Next, the configuration of the intermediate transfer unit (intermediate transfer device) 100 in this embodiment will be further described. Fig. 2 is a schematic perspective view of the intermediate transfer unit 100 in this embodiment. In Fig. 2, the intermediate transfer belt 111 is shown with a part of the rear side in its width direction (a direction substantially perpendicular to the moving direction of the surface) cut away.

[0032] The intermediate transfer unit 100 is configured by integrating a belt conveying section (belt conveying device) 110 and a belt cleaning device 150.

[0033] The belt conveying section 110 of the intermediate transfer unit 100 has a drive roller 112, a tension roller 113, and an idler roller 115 as tension rollers (support rollers) that suspend the intermediate transfer belt 111 so as to be rotatable. Both ends of each of these tension rollers 112, 113, and 115 in the direction of their respective rotation axes are rotatably supported by bearings (not shown) provided on an intermediate transfer frame 116 as a support body. In this embodiment, the drive roller 112 also functions as a secondary transfer inner roller to which a secondary transfer voltage is applied.

[0034] A drive coupling 117 serving as a drive connecting member is provided at the rear end of the drive roller 112 in the direction of the rotation axis. When the intermediate transfer unit 100 is attached to the apparatus main body 2, the drive roller 112 receives a driving force from the drive unit 130 via the drive coupling 117 and rotates. The intermediate transfer belt 111 is conveyed by the drive roller 112 being driven to rotate. The tension rollers other than the drive roller 112 are rotated in accordance with the rotation of the intermediate transfer belt 111. In this embodiment, the intermediate transfer belt 111 is configured as an endless belt (film) formed using polyimide resin.

[0035] Between a tension roller 113 that stretches the intermediate transfer belt 111 and an idler roller 115, primary transfer rollers 114a to 114d are disposed. Both ends of the primary transfer rollers 114a to 114d in the direction of their respective rotational axes are rotatably supported by bearings (not shown) that are movably provided on the intermediate transfer frame 116. The bearings of the primary transfer rollers 114a to 114d are biased from the inner periphery side toward the outer periphery side of the intermediate transfer belt 111 by elastic members (not shown) such as compression coil springs as biasing means. Furthermore, the primary transfer rollers 114a to 114d are movable between a biasing position where the intermediate transfer belt 111 is pressed against the photosensitive drums 3a to 3d to bring the intermediate transfer belt 111 into contact with the photosensitive drums 3a to 3d, and a retracted position where the intermediate transfer belt 111 is separated from the photosensitive drums 3a to 3d. When the primary transfer rollers 114a to 114d are in the urging position, they can transfer toner images from the photosensitive drums 3a to 3d to the intermediate transfer belt 111. In this embodiment, the idler roller 115 is also movable between the urging position where the intermediate transfer belt 111 contacts the photosensitive drums 3a to 3d and the retracted position where the intermediate transfer belt 111 is separated from the photosensitive drums 3a to 3d.

[0036] 4 is a schematic cross-sectional view for explaining the tension state of the intermediate transfer belt 111 in this embodiment. Figures 4(a), (b), and (c) respectively show the tension state of the intermediate transfer belt 111 in the "full separation" state, the "color contact" state, and the "monochrome contact" state, which will be described below.

[0037] The belt conveying section 110 of the intermediate transfer unit 100 has a contact / separation mechanism (movement mechanism) 121 that moves the primary transfer rollers 114a-114d and the idler roller 115 in a direction toward and away from a common tangential plane (here, also simply referred to as a "photoconductor tangential plane") PL on the side of the multiple photoconductor drums 3a-3d that contacts the intermediate transfer belt 111. The contact / separation mechanism 121 moves the bearings of the rollers in the above directions, thereby enabling each roller to be located at a first position (biased position) and a second position (retracted position) that is farther away from the photoconductor tangential plane PL than the first position.

[0038] As shown in FIG. 4(a), when the intermediate transfer unit 100 is attached to or detached from the apparatus main body 2 for maintenance or replacement, the intermediate transfer belt 111 is in a "full separation" state. In the "full separation" state, all the primary transfer rollers 114a to 114d and the idler roller 115 are disposed at the retracted positions, and the intermediate transfer belt 111 is separated from all the photosensitive drums 3a to 3d. This prevents the intermediate transfer belt 111 from rubbing against the photosensitive drums 3a to 3d when the intermediate transfer unit 100 is attached or detached, thereby suppressing damage to the intermediate transfer belt 111 and the photosensitive drums 3a to 3d and improving maintainability. In addition, as will be described in detail later, in this embodiment, the intermediate transfer belt 111 is in a "full separation" state even in the "cleaning mode".

[0039] 3(b), in full-color mode (full-color printing), the intermediate transfer belt 111 is stretched in a "color contact" state. In the "color contact" state, all of the primary transfer rollers 114a to 114d and the idler roller 115 are disposed in the biasing position, and the intermediate transfer belt 111 contacts all of the photosensitive drums 3a to 3d. This makes it possible to print a full-color image using all of the primary transfer rollers 114a to 114d and the photosensitive drums 3a to 3d.

[0040] As shown in FIG. 3(c), in the monochrome mode (black-and-white print mode), the intermediate transfer belt 111 is stretched in a "monochrome contact" state. In the "monochrome contact" state, the primary transfer rollers 114a to 114c for each color (herein also referred to as "color") of yellow, magenta, and cyan are disposed in the retreated position, and the primary transfer roller 114d for black and the idler roller 115 are disposed in the biased position, so that the intermediate transfer belt 111 contacts only the black photosensitive drum 3d among the four photosensitive drums 3a to 3d. This makes it possible to print a monochrome image (black-and-white image) using the primary transfer roller 114d and the photosensitive drum 3d for black. In the monochrome mode, the color photosensitive drums 3a to 3c and the like are not rotated, so that the life of the color photosensitive drums 3a to 3c and the like can be extended. In the monochrome mode, the rotation of the rotary members of the color developing device 7 and the application of voltage to the color charging roller 5, the developing device 7 and the primary transfer roller 7 are not performed.

[0041] Here, in this embodiment, during print standby, the intermediate transfer belt 111 is tensioned in a "monochrome contact" state as shown in FIG. 4(c). This is to shorten the time from when a print command is issued until the recording material S on which the first image is formed is output in a monochrome mode that is generally used frequently in business use, for example. Note that, for the same reason, the black image forming unit Pd among the multiple image forming units Pa to Pd is disposed at the most downstream position in the forward rotation direction of the intermediate transfer belt 111. However, this is not limited to this, and the tension of the intermediate transfer belt 111 during print standby may be in a "full separation" state or a "color contact" state.

[0042] In this embodiment, the contact / separation mechanism 121 includes a separation shaft 118, a separation member 119, and a separation coupling 120, as shown in FIG. 3. The separation shaft 118 is rotatably supported at both ends in the rotation axis direction by the intermediate transfer frame 116. The separation coupling 120 as a drive connecting member is provided at the rear end of the separation shaft 118 in the rotation axis direction. The separation shaft 118 as a drive transmission member rotates by receiving a driving force from the drive unit 130 via the separation coupling 120 in a state in which the intermediate transfer unit 100 is mounted on the apparatus main body 2. As a result, the separation shaft 118 can selectively move the separation member 119 as an acting part acting on the bearings of the primary transfer rollers 114a to 114d and the idler roller 115 to a position where the intermediate transfer belt 111 takes the above-mentioned three tension forms.

[0043] In this embodiment, the belt transport section 110 of the intermediate transfer unit 100 is made up of an intermediate transfer belt 111, tension rollers 112, 113, and 115 for the intermediate transfer belt 111, primary transfer rollers 114a to 114d, a contact / separation mechanism 121, an intermediate transfer frame 116, and the like.

[0044] In this embodiment, a belt cleaning device 150 is attached to the belt conveyance 110 of the intermediate transfer unit 100. In this embodiment, the belt cleaning device 150 is positioned by the tension roller 113 and attached to the belt conveyance section 110. As a result, the belt conveyance section 110 and the belt cleaning device 150 are integrated to configure the intermediate transfer unit 100.

[0045] 3.Belt cleaning device Next, the configuration of the belt cleaning device 150 in this embodiment will be further described. FIG. 5 is a schematic perspective view showing the vicinity of the belt cleaning device 150 in the intermediate transfer unit 100. In FIG. 5, the intermediate transfer belt 111 is shown with a part of the rear side in its width direction (direction substantially perpendicular to the moving direction of the surface) cut away. FIG. 6(a) is a schematic cross-sectional view (cross-section substantially perpendicular to the rotation axis direction of the photosensitive drum 3 and the tension roller of the intermediate transfer belt 111) of the vicinity of the belt cleaning device 150. FIG. 6(b) is a schematic diagram showing the discharge path of collected materials from the belt cleaning device 150 (schematic cross-sectional side view of the belt cleaning device 150 seen from the left side).

[0046] As shown in FIG. 5 and FIG. 6(a), in this embodiment, the belt cleaning device 150 is disposed at a position facing the tension roller 113 with the intermediate transfer belt 111 interposed therebetween. The belt cleaning device 150 has a cleaning container 151, and a cleaning blade 152 and a conveying screw 153 provided inside the cleaning container 151. The cleaning blade 152 as a cleaning member is disposed in contact with the surface of the intermediate transfer belt 111 wound around the tension roller 113. The belt cleaning device 150 scrapes off deposits such as secondary transfer residual toner and paper powder from the surface (outer peripheral surface) of the rotating intermediate transfer belt 111 by the cleaning blade 152, and stores them in the cleaning container 151. The contact portion between the cleaning blade 152 and the intermediate transfer belt 111 in the circumferential direction (positive rotation direction) of the intermediate transfer belt 111 is a belt cleaning section CL where the belt cleaning device 150 removes deposits on the intermediate transfer belt 111. A conveying screw 153 as a collected toner conveying member conveys collected matters such as secondary transfer residual toner and paper powder, which are collected in the cleaning container by the cleaning blade 152, to the outside of the cleaning container 151.

[0047] 5 shows a drive connection between the belt conveying section 110 and the belt cleaning device 150 in the intermediate transfer unit 100. A drive transmission gear 122 serving as a drive transmission member is provided at the front end of the tension roller 113 in the direction of its rotation axis. A screw input gear 154 serving as a drive transmission member is provided at the front end of the conveying screw 153 in the direction of its rotation axis. With the belt cleaning device 150 attached to the belt conveying section 110, the drive transmission gear 122 and the screw input gear 153 mesh with each other. As a result, when the tension roller 113 rotates, the conveying screw 153 also rotates.

[0048] As shown in FIG. 6B, the toner, paper powder, and other collected materials collected by the belt cleaning device 150 are conveyed by the conveying screw 153, discharged from the cleaning container 151, and conveyed to the waste toner container 22 via the waste toner conveying path (container) 160. As described above, in this embodiment, the conveying screw 153 of the belt cleaning device 150 is driven in conjunction with the intermediate transfer belt 111 by a common driving source. During image formation, the conveying screw 153 is rotated in a forward direction indicated by an arrow R3 in FIG. 6A, for example, to convey the toner in the cleaning container 151 in a direction from the rear side to the front side (from the left side to the right side in FIG. 6B). Then, the toner in the cleaning container 151 is discharged from the discharge port 155 provided at the front end of the cleaning container 151 toward the waste toner conveying path 160. In this embodiment, the toner is conveyed by gravity through the connection between the discharge port 155 and the receiving port 161 on the waste toner conveying path 160 side.

[0049] Here, the discharge port 155 and the receiving port 161 are connected when the intermediate transfer unit 100 is attached to the apparatus main body 2. A shutter may be provided at the connection between the discharge port 155 and the receiving port 161 to cover the opening when the connection is released. The toner discharged from the belt cleaning device 150 may be merged with toner discharged from other discharge sources such as the drum cleaning device 6 in the waste toner transport path 160 and transported to the waste toner container 22. A transport screw or the like may be provided in the waste toner transport path 160 as a recovered toner transport member.

[0050] Inside the cleaning container 151, between the inner wall of the cleaning container 151 and the transport screw 153, a collection (immobile layer) of collected matter (foreign matter) such as untransported toner and paper powder occurs.

[0051] 4. Installing and Removing the Intermediate Transfer Unit Next, a description will be given of the attachment and detachment (insertion and removal) of the intermediate transfer unit 100 to and from the apparatus main body 2 in this embodiment. Figure 7 is a perspective view that shows a main body frame 300 provided in the apparatus main body 2 and the intermediate transfer unit 100 in a state where it is attached to the apparatus main body 2.

[0052] The main body frame 300 is composed of a bottom plate 301, a front plate 302, a rear plate 303, and a left side plate 304 which are erected on the bottom plate 301. The front plate 302 and the rear plate 303 are provided facing each other and approximately parallel to each other. The left side plate 304 is provided on the left side of the device main body 2, approximately perpendicular to the front plate 302 and the rear plate 303 so as to connect them. In addition, a right door 305 is provided for opening and closing the right side of the device main body 2 so as to divide the conveying path (FIG. 1) of the recording material S from the feeding roller 11 to the fixing device 13 into the front side and the back side of the recording material S. The right door 305 is attached to the front plate 302 and the rear plate 303 so as to be rotatable about a rotation axis line approximately parallel to the front-rear direction by a rotation shaft 306. The right door 305 is opened and closed by an operator operating a handle portion or the like provided on the right door 305.

[0053] By opening the right door 305, an operator can access the intermediate transfer unit 100. The intermediate transfer unit 100 can be removed from the device body 2 by pulling it out to the right side of the device body 2. Conversely, the intermediate transfer unit 100 can be attached to the device body 2 by inserting it into the left side of the device body 2. The intermediate transfer unit 100 can be attached to and detached from the device body 2 by an operator operating a handle 123 (FIG. 3) provided on the intermediate transfer unit 100. Rails 307 are attached to the front plate 302 and the rear plate 303 as mounting portions that support the intermediate transfer unit 100. The intermediate transfer unit 100 is guided by the rails 307 and moves in a substantially horizontal direction (in the direction of the arrow in FIG. 7) approximately parallel to the planes of the front plate 302 and the rear plate 303, making it detachable (insertable and removable) from the device body 2.

[0054] When the intermediate transfer unit 100 is mounted in a predetermined mounting position in the apparatus body 2, the belt cleaning device 150 provided in the intermediate transfer unit 100 is connected to a waste toner transport path 160 (FIG. 6(b)) provided in the apparatus body 2. When the intermediate transfer unit 100 is mounted in the above mounting position, a drive coupling 117 (FIG. 3) and a separation coupling 120 provided on the rear side of the intermediate transfer unit 100 are each connected to a drive unit 130 provided in the apparatus body 2. In this way, when the intermediate transfer unit 100 is mounted in or removed from the apparatus body 2, connection and disconnection of the drive force between the intermediate transfer unit 100 and the drive unit 130 and connection and disconnection between the belt cleaning device 150 and the waste toner transport path 160 can be performed.

[0055] 5. Control Configuration FIG. 8 is a schematic block diagram showing the control mode of the main part of the image forming apparatus 1 of this embodiment. The image forming apparatus 1 is provided with a control unit 140. The control unit 140 is configured to have a CPU 141 as an arithmetic control means which is a central element for performing arithmetic processing, a storage unit (storage medium) 142 such as a ROM, RAM, or non-volatile memory as a storage means, and an input / output circuit (I / F) 143. The RAM, which is a rewritable memory, stores information input to the control unit 140, detected information, arithmetic results, etc. The ROM also stores a control program, a data table obtained in advance, etc. The non-volatile memory stores various settings, usage history information, etc. The input / output circuit inputs and outputs signals between the control unit 140 and devices connected thereto.

[0056] The control unit 140 is connected to each section (various driving devices, various power sources, various sensors, etc.) of the image forming apparatus 1. For example, in this embodiment, the control unit 140 is connected to the exposure device 7, the charging power source E1, the developing power source E2, the primary transfer power source E3, the secondary transfer power source E4, etc. Although not shown in the figure, in this embodiment, the charging power source E1, the developing power source E2, and the primary transfer power source E3 are provided independently for the image forming units P for each color. In addition, the control unit 140 is connected to the driving unit 130. In this embodiment, the drive unit 130 includes a drum drive device (image carrier drive unit) 131 that drives the photosensitive drums 3 for each color and the conveying screw 63 of the drum cleaning device 6, a belt drive device (belt drive unit, cleaning drive unit) 132 that drives the intermediate transfer belt 111 and the conveying screw 153 of the belt cleaning device 150, a contact and separation drive device 133 that drives the contact and separation mechanism (movement mechanism) 121, and a development drive device (development drive unit) 134 that drives the development device 5 for each color. Although not shown in the figure, in this embodiment, the drum drive device 131 is provided for color and black. Although not shown in the figure, in this embodiment, the development drive device 134 is provided for color and black. In addition, an operation unit 200 is connected to the control unit 140. In addition, an original reading unit (not shown) provided in the image forming apparatus 1 and an external device 500 connected to the image forming apparatus 1 are connected to the control unit 140.

[0057] The control unit 140 can control each part of the image forming apparatus 1 to execute the image forming operation described above. In addition, as will be described later in detail, the control unit 140 can control each part of the image forming apparatus 1 (such as the belt driving device 132 and the approach / separation driving device 133) to execute a "cleaning mode."

[0058] 6. Challenges The intermediate transfer belt 111 may be subject to fatigue damage due to changes over time or long-term operation, and therefore it is desirable to replace it periodically, for example, according to the amount of use. Similarly, the cleaning blade 152 of the belt cleaning device 150 is also subject to wear due to use, and therefore it is desirable to replace it periodically, for example, according to the amount of use. In this embodiment, the intermediate transfer unit 100, which is configured by integrating the belt conveying section 110 and the belt cleaning device 150, is detachable from the device main body 2. Therefore, in this embodiment, the intermediate transfer belt 111 and further the belt cleaning device 150 (cleaning blade 152) can be easily replaced by removing the intermediate transfer unit 100 from the device main body 2 and replacing the entire intermediate transfer unit 100.

[0059] However, as described above, when an operator such as a user or a maintenance worker removes the intermediate transfer unit 100 from the apparatus main body 2, toner, paper powder, and other adhering matter may remain on the intermediate transfer belt 111.

[0060] For example, during normal operation of the image forming apparatus 1, toner and external additives are attached to the surface of the intermediate transfer belt 111 due to a phenomenon generally called "fogging." Fogging is a phenomenon in which toner with a low charge amount or toner charged with a polarity opposite to the normal charge polarity adheres to a non-image portion on the photosensitive drum 3 from the developing device 5. The toner that has caused the fogging (herein also referred to as "fogging toner") moves onto the intermediate transfer belt 111 by physical or electrostatic adhesion at the primary transfer portion N1 and adheres to the intermediate transfer belt 111. The fogging toner attached to the intermediate transfer belt 111 is of a level that does not affect the quality of the image even if it is transferred to the recording material S at the secondary transfer portion N2. In addition, the fogging toner and external additives attached to the intermediate transfer belt 111 also play a role in suppressing excessive friction between the cleaning blade 152 of the belt cleaning device 150 and the intermediate transfer belt 111. Therefore, during normal operation of the image forming apparatus 1, generally no operation is performed to remove the fog toner and external additives adhering to the intermediate transfer belt 111, and essentially the amount of toner and external additives adhering to the surface of the intermediate transfer belt 111 is always the same as the fog toner.

[0061] During normal operation of the image forming apparatus 1, a test image for color misregistration correction and a test image for density correction, which are made of a toner image, are generally formed on the intermediate transfer belt 111 at a predetermined timing. This test image is read by, for example, a sensor 24 (FIG. 1) provided at a position opposite to the idler roller 115, passes through the secondary transfer section N2 without being transferred to the recording material S, and is removed from the intermediate transfer belt 111 by the belt cleaning device 150. However, for example, when a test image is formed on the intermediate transfer belt 111 in the post-rotation process, the driving of the intermediate transfer belt 111 may be stopped before the test image is removed from the intermediate transfer belt 111 by the belt cleaning device 150. This is to suppress shortening of the life span of the photosensitive drum 3, the intermediate transfer belt 111, and other members by shortening the driving time of these members as much as possible during normal operation of the image forming apparatus 1. 9A, when the intermediate transfer belt 111 stops, a test image Tt remains attached to the surface between the secondary transfer portion N2 and the belt cleaning device 150 in the forward rotation direction of the intermediate transfer belt 111. If an image is subsequently formed, this test image Tt is removed by the belt cleaning device 150 in the pre-rotation process. However, if the intermediate transfer unit 100 is removed from the apparatus main body 2 without subsequently forming an image, the test image Tt remains attached to the intermediate transfer belt 111.

[0062] Furthermore, during normal operation of the image forming apparatus 1, a predetermined toner image may be interposed between the photosensitive drum 3 and the intermediate transfer belt 111, which are in contact with the intermediate transfer belt 111 while the image forming apparatus 1 is stopped. This is to suppress the influence on image formation caused by changes in the physical or chemical state of the surface of the photosensitive drum 3 and the surface of the intermediate transfer belt 111 due to the photosensitive drum 3 and the intermediate transfer belt 111 being left in direct contact with each other for a long period of time. For example, before stopping the photosensitive drum 3 and the intermediate transfer belt 111 after the post-rotation process, a band-shaped halftone image or solid image is formed on the photosensitive drum 3, which is in contact with the intermediate transfer belt 111 while the image forming apparatus 1 is stopped. This image is formed along the width direction of the intermediate transfer belt 111 (the direction of the rotation axis of the photosensitive drum 3), for example, in almost the entire area where the photosensitive drum 3 and the intermediate transfer belt 111 are in contact with each other. Then, the photosensitive drum 3 and the intermediate transfer belt 111 are stopped so that this image is interposed between the photosensitive drum 3 and the intermediate transfer belt 111 at the contact portion between the photosensitive drum 3 and the intermediate transfer belt 111. In this case, as shown in FIG. 9B, when the intermediate transfer belt 111 stops, the belt-like image (here, also referred to as a "spacer image") Ts is present on the intermediate transfer belt 111 that is in contact with the photosensitive drum 3. In this embodiment, as described above, during print standby, the tension state of the intermediate transfer belt 111 is set to the "monochrome contact" state shown in FIG. 4C, so that the spacer image Ts is present between the black photosensitive drum 3d and the intermediate transfer belt 111. This spacer image Ts may adhere to the surfaces of both the photosensitive drum 3 and the intermediate transfer belt 111, but when image formation is performed thereafter, it is removed by the drum cleaning device 6 and the belt cleaning device 150 in the pre-rotation process. However, if the intermediate transfer unit 100 is removed from the apparatus main body 2 without image formation thereafter, the spacer image Ts remains attached on the intermediate transfer belt 111.

[0063] In this way, if toner or paper dust such as fog toner, test images, spacer images, etc. is present on the intermediate transfer belt when the operator removes the intermediate transfer unit 100 from the device main body 2, there is a possibility that the operator or the installation environment of the image forming apparatus 1 will become dirty.

[0064] Furthermore, in the case where the intermediate transfer unit 100 is provided with the belt cleaning device 150 as in this embodiment, if a large amount of toner, paper powder, etc. remains in the belt cleaning device 150 when the intermediate transfer unit 100 is removed from the apparatus main body 2, there is a possibility that this may leak out and soil the operator or the installation environment of the image forming apparatus 1.

[0065] Furthermore, in recent years, from the viewpoint of environmental protection and effective use of resources, there has been a growing demand for the reuse of image forming apparatuses and their replacement units. Used products of image forming apparatuses and their replacement units are collected from users, and the parts are cleaned, regenerated, and the like, and are shipped to the market again as regenerated products with quality assurance. If a large amount of toner or paper powder remains in the belt cleaning device 150 when the intermediate transfer unit 100 is removed from the apparatus main body 2, the following possibility may occur. That is, when the intermediate transfer unit 100 is collected from the market for reuse, the toner or the like may scatter in the packaging box due to vibrations during transportation, and the inside of the intermediate transfer unit 100 may become dirty. Then, the used product may become unsuitable as a base for reuse, or may be difficult to clean even if it can be reused.

[0066] For example, it is conceivable to drive the conveying screw 153 of the belt cleaning device 150 in the post-rotation process so as to always sufficiently reduce the amount of toner in the belt cleaning device 150 during normal operation of the image forming apparatus 1. However, in that case, the driving time of the conveying screw 153 of the belt cleaning device 150 and other members such as the intermediate transfer belt 111 that operates in conjunction with it may become longer, and their lifespan may become shorter. Therefore, generally, a relatively large amount of toner and paper powder is accumulated in the belt cleaning device 150 during normal operation of the image forming apparatus 1.

[0067] Therefore, when an operator removes the intermediate transfer unit 100 from the apparatus main body 2, it is desirable to prevent toner and paper powder adhering to the intermediate transfer belt 111 from soiling the operator or the installation environment of the image forming apparatus 1. At that time, it is also desirable to prevent toner and paper powder remaining in the belt cleaning device 150 from leaking and soiling the operator or the installation environment of the image forming apparatus 1. Furthermore, it is desirable to prevent toner and the like from scattering from the belt cleaning device 150 when the intermediate transfer unit 100 is collected.

[0068] 7. Cleaning Mode Next, a cleaning mode for the intermediate transfer unit 100 that can be executed prior to removal of the intermediate transfer unit 100 from the apparatus main body 2 in this embodiment will be described.

[0069] Fig. 10 is a flow chart showing an outline of a procedure for replacing the intermediate transfer unit 100, as an example of a case where an operator removes the intermediate transfer unit 100 from the apparatus main body 2. Fig. 11 is a schematic diagram showing an example of a display screen displayed on the operation unit 200 in relation to the cleaning mode.

[0070] In this embodiment, the usage limit (lifespan) of the intermediate transfer unit 100 (particularly, the intermediate transfer belt 111 in this embodiment) is set by the number of sheets of recording material S on which image formation has been performed (also referred to as the "number of sheets passed" here). The number of sheets passed can be converted into the number of sheets of recording material S of a predetermined size and used. Specifically, in this embodiment, the usage limit of the intermediate transfer unit 100 (particularly, the intermediate transfer belt 111 in this embodiment) is set to 200,000 sheets of A4-sized recording material S as the number of sheets passed. Note that, since durability performance differs from product to product, the usage limit number of sheets passed is not limited to the numerical value in this embodiment. The control unit 140 counts the number of sheets passed every time image formation is performed, and updates and stores the cumulative number of sheets passed since the start of use of the intermediate transfer unit 100 in the memory unit 142 as information on the amount of use since the start of use of the intermediate transfer unit 100 (when new). Then, when the cumulative number of sheets of paper passed stored in the memory unit 142 reaches a preset threshold value (200,000 sheets of A4 size in this embodiment), the control unit 140 can detect that the intermediate transfer unit 100 has reached its usage limit. In this embodiment, the control unit 140 (more specifically, the CPU 141) functions as a detection unit that detects that the intermediate transfer unit 100 has reached its usage limit.

[0071] When the control unit 140 detects that the intermediate transfer unit 100 has reached its usage limit (S101), it notifies the user that the intermediate transfer unit 100 has reached its usage limit. In this embodiment, at this time, the control unit 140 controls the operation unit 200 to display information (herein also referred to as "replacement notification") that prompts the user to replace the intermediate transfer unit 100, as shown in FIG. 11(a) (S102). In the illustrated example, the replacement notification is a message that prompts the user to replace the intermediate transfer unit 100. However, this is not limited to this, and it may simply display that the intermediate transfer unit 100 has reached its usage limit. Also, in this embodiment, at this time, the control unit 140 controls the operation unit 200 to display a replacement start icon 202 for inputting that the user will start the replacement work of the intermediate transfer unit 100, as shown in FIG. 11(a) (S102). The user can select whether to replace the intermediate transfer unit 100 or to continue using the image forming apparatus 1 (intermediate transfer unit 100). If the user selects to replace the intermediate transfer unit 100, the user operates the replacement start icon 202, and if the user selects to continue using the unit, the user proceeds to use a desired function such as a copy function.

[0072] If the user selects continued use, the replacement notification can be displayed on the operation unit 200 at all times until the intermediate transfer unit 100 is replaced, as shown in FIG. 11(a). Alternatively, during maintenance work, the maintenance worker may instruct the control unit 140 to display information on the operation unit 200 indicating whether the intermediate transfer unit 100 has reached its usage limit. This display may be the same as the replacement notification, or may simply indicate, for example, the usage history (number of sheets passed) of the intermediate transfer unit 100. The maintenance worker can check this display and decide whether to replace the intermediate transfer unit 100. In this case, the control unit 140 may not automatically display the replacement notification on the operation unit 200 even if the intermediate transfer unit 100 has reached its usage limit.

[0073] When the user selects replacement of the intermediate transfer unit 100 and operates the replacement start icon 202 displayed on the operation panel 200 (S103), the control section 140 executes the cleaning mode of the intermediate transfer unit 100 (S104).

[0074] FIG. 12 is a timing chart showing the operation state of each part in the cleaning mode in this embodiment. In the cleaning mode, a belt cleaning process (belt cleaning operation) is performed to remove adhesions such as toner and paper powder remaining on the surface of the intermediate transfer belt 111 after the post-rotation process. In the belt cleaning process, the intermediate transfer belt 111 is brought into a state in which toner such as fog toner does not newly adhere to it (or is difficult to adhere to it). Then, in the belt cleaning process, the intermediate transfer belt 111 is rotated forward to remove adhesions from the surface of the intermediate transfer belt 111 by the belt cleaning device 150. In this embodiment, while the image forming apparatus 1 is stopped, the tension state of the intermediate transfer belt 111 is in a "monochrome contact" state. When the control unit 140 starts the cleaning mode, first, the control unit 140 controls the tension state of the intermediate transfer belt 111 to be in a "full separation" state by the contact / separation mechanism 121 (t1). Thereafter, the control unit 140 controls the belt driving device 132 to rotate the intermediate transfer belt 111 in the forward direction for approximately one revolution of the intermediate transfer belt 111 (t2 to t3). At this time, the photosensitive drum 3 and the developing device 5 (developing sleeve 52) of each image forming portion P are kept stopped. At this time, high voltages such as the charging voltage, developing voltage, primary transfer voltage, and secondary transfer voltage of each image forming portion P are kept OFF. In this embodiment, the rotation speed of the intermediate transfer belt 111 at this time is the same as that during normal image formation. In addition, if a mechanism for separating the secondary transfer outer roller 8 from the intermediate transfer belt 8 is provided, the secondary transfer outer roller 8 may be separated from the intermediate transfer belt 8 at this time.

[0075] In this embodiment, the period from t1 to t3 in the cleaning mode is the period of the belt cleaning process. However, in this embodiment, since the conveying screw 153 and the intermediate transfer belt 111 rotate in conjunction with each other, the collected material is also discharged from the cleaning container 151 during the forward rotation of the intermediate transfer belt 111 in this belt cleaning process.

[0076] After the post-rotation process, the toner, paper powder, and other deposits may remain between the most upstream primary transfer unit N1a and the belt cleaning unit CL along the forward rotation direction of the intermediate transfer belt 111. Therefore, in this embodiment, the forward rotation distance of the intermediate transfer belt 111 in the belt cleaning process is set to at least approximately one revolution of the intermediate transfer belt 111. Since the arrangement of the photosensitive drum 3, the belt cleaning device 150, and the like differs for each product, the forward rotation distance of the intermediate transfer belt 111 required for the belt cleaning process is not limited to the numerical value of this embodiment. However, the forward rotation distance of the intermediate transfer belt 111 in the belt cleaning process is often sufficient if it is 10 revolutions or less of the intermediate transfer belt 111, preferably 5 revolutions or less, and typically 3 revolutions or less.

[0077] As described above, in this embodiment, the spacer image Ts is present between the black photosensitive drum 3d and the intermediate transfer belt 111 while the image forming apparatus 1 is stopped. The spacer image Ts is, for example, a belt-shaped image formed over substantially the entire width of the intermediate transfer belt 111, and contains a relatively large amount of toner. Therefore, in a configuration in which the spacer image Ts is formed, it is important to remove the spacer image Ts in the belt cleaning process. From this perspective, the forward rotation distance of the intermediate transfer belt 111 required for the belt cleaning process can be at least the distance until the area on the intermediate transfer belt 111 that was at the primary transfer unit N1 at the most upstream in the forward rotation direction of the intermediate transfer belt 111 among the primary transfer units N1 where the spacer image Ts is arranged passes through the belt cleaning unit CL. In this embodiment, since the spacer image Ts is arranged at the primary transfer unit N1d for black, the forward rotation distance of the intermediate transfer belt 111 required for the belt cleaning process can be at least the distance until the area on the intermediate transfer belt 111 that was at the primary transfer unit N1d for black passes through the belt cleaning unit CL. As described above, the black image forming unit Pd is often disposed at the most downstream position in the forward rotation direction of the intermediate transfer belt 111. In other words, the forward rotation distance of the intermediate transfer belt 111 required for the belt cleaning process can be at least the distance until the area on the intermediate transfer belt 111 that was at the most downstream primary transfer unit N1d in the forward rotation direction of the intermediate transfer belt 111 passes through the belt cleaning unit CL. In general, the distance from this black primary transfer unit N1d (the most downstream primary transfer unit N1d in the forward rotation direction of the intermediate transfer belt 111) to the belt cleaning unit CL is approximately half a circumference of the intermediate transfer belt 111.

[0078] In addition, in this embodiment, in the cleaning mode, a toner discharge step (toner discharge operation) is also performed to transport the collected matter (collected toner) remaining inside the cleaning container 151 to the outside of the cleaning container 151. It is preferable to perform the toner discharge step after the belt cleaning step so that the toner collected in the belt cleaning step can be discharged. In the toner discharge step, the conveying screw 153 is rotated forward by an amount necessary to sufficiently discharge the collected matter from the cleaning container 151 so as to suppress the above-mentioned problems. In addition, in the toner discharge step, it is preferable to perform an operation to break up the immovable layer of the collected matter occurring inside the cleaning container 151 as described above. It is preferable to perform an operation to sufficiently discharge the collected matter from the cleaning container 151 after performing an operation to break up the immovable layer of the collected matter so that the collected matter is finally sufficiently discharged from the cleaning container 151. The collected matter discharged from the cleaning container 151 is transported to the waste toner collection container 22 via the waste toner transport path 160 as described above.

[0079] In this embodiment, in the toner discharging process, the conveying screw 153 is rotated forward and backward. In this embodiment, since the conveying screw 153 and the intermediate transfer belt 111 rotate in conjunction with each other, the control unit 140 controls the intermediate transfer belt 111 to rotate forward and backward, and the conveying screw 153 to rotate forward and backward (t3 to t4). In addition, in this embodiment, the conveying screw 153 is rotated forward and backward alternately multiple times. By rotating the conveying screw 153 backward, a conveying force by the conveying screw 153 is applied to a different place inside the cleaning container 151 than when the conveying screw 153 is rotated forward, so that the immobile layer of the collected material can be broken down. By alternately rotating the conveying screw 153 forward and backward multiple times, the effect of breaking down the immobile layer of the collected material can be obtained more reliably. In addition, by making the rotation speed of the conveying screw 153 different between forward and reverse rotation, the conveying force of the conveying screw 153 differs between forward and reverse rotation, and the effect of breaking down the immovable layer is enhanced. At this time, it is preferable to make at least one of the rotation speeds of the forward and reverse rotations faster than the rotation speed of the forward rotation during image formation. This is from the viewpoint of increasing the effect of breaking down the immovable layer and from the viewpoint of shortening the time required for the cleaning mode (toner discharge process). From the viewpoint of effectively breaking down the immovable layer by applying a force different from that during image formation to the immovable layer of the collected material, it is preferable to make the rotation speed of the reverse rotation faster than the rotation speed of the forward rotation, and to make the rotation speed of the reverse rotation faster than the rotation speed of the forward rotation during image formation. However, this is not limited to this, and for example, the rotation speeds of the forward and reverse rotations may be made faster than the rotation speed of the forward rotation during image formation, and the rotation speeds of the forward and reverse rotations may be made different. This operation breaks up the collected matter that is not transported by the transport screw 153 and remains inside the cleaning container 151 as a non-moving layer, and makes it possible for the collected matter to be transported again by the transport screw 153 to the outside of the cleaning container 151. In this embodiment, five sets of forward and reverse rotations of 1 / 4 rotation of the intermediate transfer belt 111 are performed, and the rotation speed during reverse rotation is set to 1.2 times the rotation speed during forward rotation.In this embodiment, the rotation speed of the forward rotation of the conveying screw 153 in the toner discharging process is the same as the rotation speed of the forward rotation during image formation. Therefore, the rotation speed of the reverse rotation of the conveying screw 153 in the toner discharging process is 1.2 times the rotation speed of the forward rotation during image formation.

[0080] In the toner discharge process, the conveying screw 153 is rotated forward again in order to sufficiently convey the collected matter remaining inside the cleaning container 151 to the outside of the cleaning container 151. In this embodiment, since the conveying screw 153 and the intermediate transfer belt 111 rotate in conjunction with each other, the control unit 140 controls the intermediate transfer belt 111 to rotate forward and the conveying screw 153 to rotate forward (t4 to t5). This final forward rotation of the intermediate transfer belt 111 also has the effect of removing again adhesions such as toner and paper powder that may remain on the surface of the intermediate transfer belt 111. In this embodiment, the final forward rotation of the conveying screw 153 is set to three revolutions of the intermediate transfer belt 111. Since the arrangement of the photosensitive drum 3, the primary transfer roller 114, and the cleaning member 152, and the specifications of the belt cleaning device 150, etc. differ for each product, the rotation setting required for discharging the collected matter is not limited to the numerical value of this embodiment. For example, in a configuration in which the primary transfer unit N1 and the belt cleaning unit CL are arranged on the same plane of the intermediate transfer belt 111, the rotation setting required for discharging the collected material may be more than half a revolution of the intermediate transfer belt 111. The forward rotation of the last conveying screw 153 can be set, for example, as follows. In other words, if the driving time of the last conveying screw 153 is ta (seconds), the time ta (seconds) can be expressed as follows: conveying distance (mm) of the conveying screw 153 / {maximum conveying capacity (mm / s) of the conveying screw 153×collected toner conveying efficiency β}. The conveying distance (length of the area in which the collected toner can be conveyed in the conveying direction of the collected toner) and the maximum conveying capacity (movement amount of the collected toner in the conveying direction of the collected toner per unit time) are determined by the configuration of the conveying screw 153 (conveying distance, pitch and number of rotations of the screw, etc.). The collected toner conveying efficiency β is a conveying efficiency that changes depending on the physical properties of the powder such as the toner that is the collected material, and is typically set in the range of 1 to 1 / 5. In other words, it is preferable that the driving time of this final conveying screw 153 be at least a time sufficient for the collected material located at the most upstream side in the conveying direction in the conveying area of ​​the conveying screw 153 to be conveyed to the most downstream side in the conveying direction and discharged from the discharge outlet 156.

[0081] In this embodiment, the period from t3 to t5 is the period of the toner discharging process in the cleaning mode. However, in this embodiment, since the conveying screw 153 and the intermediate transfer belt 111 rotate in conjunction with each other, during the discharge of the collected matter from the cleaning container 151 in this toner discharging process, the deposits are also removed from the surface of the intermediate transfer belt 111.

[0082] After the cleaning mode has ended as described above, the user opens the right door 305 and replaces the intermediate transfer unit 100 with a new one that has been prepared separately. The control unit 140 may control the operation unit 200 to display information notifying the user that the cleaning mode is being executed, that the cleaning mode has ended, and the like. Furthermore, when the replacement start icon 202 is operated, the control unit 140 may control the operation unit 200 to display information (message, image, video, etc.) notifying the user of the replacement procedure for the intermediate transfer unit 100. Alternatively, similar information may be displayed when the cleaning mode has ended.

[0083] Thereafter, when the user closes the right door 305, the control unit 140 controls the operation unit 200 to display a replacement completion icon 203 for the user to confirm the completion of replacement (S105). Then, when the user operates the replacement completion icon 203, the control unit 140 controls the operation unit 200 to reset the cumulative number of sheets passed through the intermediate transfer unit 100 stored in the storage unit 142 to an initial value (zero in this embodiment) (S106). At this time, the control unit 140 may also control the intermediate transfer unit 100 to perform an initial adjustment. The initial adjustment of the intermediate transfer unit 100 may include an operation of forming a predetermined toner image on the intermediate transfer belt 111 and supplying toner and external additives to the belt cleaning unit CL.

[0084] After the replacement, the old intermediate transfer unit 100 is collected, for example, in a packaging box (not shown) that the new intermediate transfer unit 100 was packed in. The collected intermediate transfer unit 100 can be regenerated as a reused item after cleaning, parts replacement, and the like.

[0085] In addition, the displays and operations described above as being performed on the operation unit 200 of the image forming apparatus 1 can be performed on an external device 500 such as a personal computer communicatively connected to the image forming apparatus 1, in addition to or instead of the displays and operations. In this case, the input / output circuit 143 functions as a notification unit for notifying the operator of information and an input unit for inputting instructions based on the operator's operation to the control unit.

[0086] In this embodiment, in order to prevent new toner such as fog toner from adhering to the intermediate transfer belt 111 in the cleaning mode, the intermediate transfer belt 111 is separated from all the photosensitive drums 3. However, this is not limited to this. By separating the intermediate transfer belt 111 from at least one of the multiple photosensitive drums 3, a suitable effect can be obtained. Also, as shown in FIG. 13, the cleaning mode may be performed in a state in which the intermediate transfer belt 111 is in contact with at least one or all of the multiple photosensitive drums 3. In this case, the photosensitive drum 3 in contact with the intermediate transfer belt 111 is rotated (forward rotation, reverse rotation) in conjunction with the intermediate transfer belt 111. However, in the image forming portion P in which the photosensitive drum 3 is in contact with the intermediate transfer belt 111, the developing device 5 (developing sleeve 52) is stopped and high voltages such as the charging voltage, developing voltage, and primary transfer voltage are kept OFF so that new toner such as fog toner is not adhering to the intermediate transfer belt 111 from the photosensitive drum 3. For example, a configuration may be considered in which the intermediate transfer belt 111 cannot be separated from the photosensitive drum 3 in the black image forming station P. In this case, the cleaning mode may be executed in a state in which the intermediate transfer belt 111 is separated from the photosensitive drum 3 in the color image forming stations P, and the intermediate transfer belt 111 is kept in contact with the photosensitive drum 3 in the black image forming station P.

[0087] In addition, in the image forming section where the photosensitive drum is in contact with the intermediate transfer belt in the cleaning mode, in the case where a developing member (developer carrier) such as a developing roller is in contact with the photosensitive drum, the following can be done. If a separation mechanism for separating the developing member from the photosensitive drum is provided, the developing member can be separated from the photosensitive drum. If such a separation mechanism is not provided, the developing member needs to be rotated together with the photosensitive drum. Therefore, in this case, the potential difference between the surface potential of the photosensitive drum and the potential of the developing member in the developing section can be set so as to suppress the movement of the toner to the photosensitive drum, thereby suppressing the adhesion of the toner to the photosensitive drum. For example, a voltage of a polarity opposite to the normal charging polarity of the toner can be applied to the developing member without charging the photosensitive drum. Another example is to apply a voltage of the same polarity as the normal charging polarity of the toner to the primary transfer roller. These may be used in combination. Even in such a configuration, for example, the above-mentioned test image and spacer image can be more reliably removed by the cleaning mode, and the adhesion of new toner to the intermediate transfer belt can be suppressed in the cleaning mode.

[0088] Thus, in this embodiment, the image forming apparatus 1 includes an image carrier (photosensitive drum) 3 that carries a toner image, a toner image forming unit (charging roller 4, exposure device 7, developing device 5, etc.) that forms a toner image on the surface of the image carrier 3, a rotatable intermediate transfer belt 111 that is stretched around a plurality of tension rollers 112, 113, and 115 and comes into contact with the image carrier 3 to form a transfer unit N1, to which the toner image is transferred from the image carrier 3 at the transfer unit N1, a cleaning device 150 that removes toner from the surface of the intermediate transfer belt 111 at a cleaning unit CL, a belt drive unit (belt drive device) 132 that drives and rotates the intermediate transfer belt 111, a control unit 140 that can control the belt drive unit 132, and an input unit (operation unit) 200 that inputs instructions based on operations by an operator to the control unit 140, and performs image formation by transferring the toner image transferred from the image carrier 3 to the intermediate transfer belt 111 from the intermediate transfer belt 111 to a recording material S. In this embodiment, the image forming apparatus 1 has a unit (intermediate transfer unit, intermediate transfer device) 100 including the intermediate transfer belt 111 and a plurality of tension rollers 112, 113, and 115, which is detachable from the apparatus body 2 of the image forming apparatus 1, and the control unit 140 can control the belt drive unit 132 to perform a belt cleaning operation (cleaning process) in which the intermediate transfer belt 111 is rotated and the surface of the intermediate transfer belt 111 is cleaned by the cleaning device 150 in response to an instruction from the input unit 200 when the unit 100 is removed from the apparatus body 2 after the last image formation before the removal and prior to the removal. In this embodiment, the image forming apparatus 1 has a contact / separation mechanism 121 that contacts and separates the intermediate transfer belt 111 from the image carrier 3, and the control unit 140 controls the contact / separation mechanism 121 to perform the belt cleaning operation in a state in which the intermediate transfer belt 111 is separated from the image carrier 3.

[0089] However, the image forming apparatus 1 may have an image carrier driving section (drum driving device) 131 that rotates the rotatable image carrier 3, and the control section 140 may be configured to control the image carrier driving section 131 so as to perform a belt cleaning operation in a state in which the image carrier 3 in contact with the intermediate transfer belt 111 is rotated. In this case, the toner image forming section has a rotatable developing member 52 that supplies toner to the surface of the image carrier 3, and a developing driving section (developing driving device) 134 that rotates and drives the developing member 52, and the control section 144 can control the developing driving section 134 so as to perform a belt cleaning operation in a state in which the developing member 52 is stopped. In this case, the toner image forming unit has a charging device 4 that charges the image carrier 3, a charging voltage application unit E1 that applies a charging voltage to the charging device 4, and a developing voltage application unit E2 that applies a developing voltage to the developing member 52, and the control unit 140 can control the charging voltage application unit E1 and the developing voltage application unit E2 to perform the belt cleaning operation without applying a charging voltage to the charging device 4 by the charging voltage application unit E1 and without applying a developing voltage to the developing member 52 by the developing voltage application unit E2.

[0090] Furthermore, the control unit 140 can control the toner image forming unit and the belt driving unit 132 so that, after the image formation, a predetermined toner image formed on the image carrier is disposed between the image carrier 3 and the intermediate transfer belt 111, and the intermediate transfer belt 111 is stopped in a state in which the intermediate transfer belt 111 is in contact with the image carrier 3 via the predetermined toner image. In this case, it is preferable that the control unit 140 controls the belt driving unit 132 so as to rotate and drive the intermediate transfer belt 111 in the rotation direction during the image formation in the belt cleaning operation, at least until the area on the intermediate transfer belt that was in the transfer unit N1 while the intermediate transfer belt 111 was stopped after the last image formation passes the cleaning unit CL. In this embodiment, the control unit 140 controls the belt driving unit 132 so as to rotate and drive the intermediate transfer belt 111 in the rotation direction during the image formation at least for one revolution of the intermediate transfer belt 111 in the belt cleaning operation. The image forming apparatus 1 may further include other image carriers 3b, 3c (for example, photosensitive drums 3b, 3c, 3d when the image carrier 3 is the photosensitive drum 3a) that carry a toner image to be transferred to the intermediate transfer belt 111, other toner image forming units that form toner images on the surfaces of the other image carriers 3b, 3c, 3d, a contact / separation mechanism 121 that contacts and separates the intermediate transfer belt 111 with respect to the other image carriers 3b, 3c, 3d, and an image carrier drive unit 131 that drives the rotation of the rotatable image carrier 3a (for example, the photosensitive drum 3a), and the control unit 140 can control the contact / separation mechanism 121 and the image carrier drive unit 131 to perform a belt cleaning operation while separating the intermediate transfer belt 111 from the other image carriers 3b, 3c, 3d and driving the rotation of the image carrier 3a with which the intermediate transfer belt 111 is in contact.

[0091] In addition, in this embodiment, the cleaning device 150 is provided in the unit 100 and is detachable from the apparatus main body 2 together with the intermediate transfer belt 111 and the multiple tension rollers 112, 113, and 115, and has a cleaning member (cleaning blade) 152 that removes toner from the surface of the intermediate transfer belt 111, a cleaning container 151 that stores the toner removed from the surface of the intermediate transfer belt 111, and a conveying member (conveying screw) 153 that conveys the toner in the cleaning container to be discharged outside the cleaning container 151, and the image forming apparatus 1 has a cleaning drive unit (belt drive unit) 132 that drives the conveying member 153 and a storage unit (waste toner conveying path 160) that stores the toner discharged from the cleaning container 151, and the control unit 140 is capable of controlling the cleaning drive unit 132 to perform a toner discharge operation (toner discharge process) that drives the conveying member 153 to discharge the toner from the cleaning container 151 after the final image formation and prior to the removal when performing a belt cleaning operation. Here, the transport member 153 may be a rotating member that rotates in a first rotation direction (forward rotation direction) during image formation, the cleaning drive unit 132 may be capable of rotationally driving the transport member 153 in the first rotation direction and a second rotation direction (reverse rotation direction) opposite to the first rotation direction, and the control unit 140 can control the cleaning drive unit 132 to rotationally drive the transport member 153 in the first rotation direction and the second rotation direction during the toner discharging operation. Furthermore, the control unit 140 can control the cleaning drive unit 132 to make at least one of the rotation speed of the transport member 153 in the first rotation direction or the rotation speed of the transport member 153 in the second rotation direction faster than the rotation speed of the transport member 153 in the first rotation direction during image formation. Furthermore, the control unit 140 can control the cleaning drive unit 132 to make the rotation speed in the second rotation direction faster than the rotation speed in the first rotation direction of the transport member 153 during the toner discharging operation. In this embodiment, the belt drive unit and the cleaning drive unit drive and rotate the intermediate transfer belt 111 and the transport member 153 in conjunction with each other using a common drive source.

[0092] In this embodiment, the image forming apparatus 1 has a storage unit 142 that stores usage history information of the intermediate transfer belt 111, and a notification unit (operation unit) 200 that notifies the operator of the information, and the control unit 140 controls the belt cleaning operation to be performed in response to an instruction from the input unit 200 when the notification unit 200 notifies the operator of information regarding replacement of the unit 100 based on the usage history information. In other words, in this embodiment, the image forming apparatus 1 has a cleaning device 150 that is detachable from the apparatus body 2 of the image forming apparatus 1, and the control unit 140 can control the cleaning drive unit 132 to perform a toner discharge operation of driving the conveying member 153 to discharge toner from the cleaning container 151 after the last image formation before the removal and prior to the removal when the cleaning device 150 is removed from the apparatus body 2.

[0093] 8. Effects According to this embodiment, the amount of toner, paper powder, and other deposits remaining on the surface of the intermediate transfer belt 111 when the intermediate transfer unit 100 is removed from the apparatus main body 2 can be significantly reduced compared to when this embodiment is not implemented. This can significantly reduce the risk of soiling the operator or the installation environment of the image forming apparatus 1. In addition, since most of the collected materials inside the cleaning container 151 have been discharged, the risk of soiling the operator or the installation environment of the image forming apparatus 1 due to toner leaked from the cleaning container 151 can also be reduced. Furthermore, since most of the collected materials inside the cleaning container 151 have been discharged, toner scattering in a packaging box can be suppressed when the intermediate transfer unit 100 is collected from the market. This can minimize the soiling of the inside of the intermediate transfer unit 100 when it is reused.

[0094] [Other Examples] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-mentioned embodiments.

[0095] In the above embodiment, the cleaning mode is executed in response to the input of an instruction by the user, but the present invention is not limited to this. For example, the cleaning mode may be automatically executed in the post-rotation process immediately after the intermediate transfer unit 100 reaches its usage limit, and then a display prompting the replacement of the intermediate transfer unit 100 may be displayed on the operation unit 200. A similar display may be displayed on an external device 500 such as a personal computer communicably connected to the image forming apparatus 1 in addition to or instead of the operation unit 200. This can reduce the time required for the user to replace the intermediate transfer unit 100. In this way, the image forming apparatus 1 has a storage unit 142 that stores the usage history information of the intermediate transfer belt 111 and a notification unit 200 that notifies the operator of the information, and the control unit 140 can control the notification unit 200 to notify the operator of information regarding the replacement of the unit 100 when the belt cleaning operation is executed based on the usage history information. This also applies to the belt conveying unit 110 and the belt cleaning device 150 when they are individually replaceable as described later.

[0096] It is also possible to send an instruction from the operation unit 200 or the external device 500 to the control unit 140 so that an operator such as a user or a maintenance worker arbitrarily executes the cleaning mode. This makes it possible to respond to the case where the intermediate transfer unit 100 needs to be replaced due to an accidental breakdown or the like before the limit of use, for example. Similarly, it is possible to respond not only to the case where the intermediate transfer unit 100 is replaced, but also to the case where the intermediate transfer unit 100 needs to be removed from the device body 2 for inspection or repair. Furthermore, when the entire image forming apparatus 1 is collected, it is possible to suppress the scattering of toner in the device body 2 or in the packaging. This is also true for the belt cleaning process and the toner discharging process in the case where the belt conveying unit 110 and the belt cleaning device 150 can be replaced separately as described later. In other words, the image forming apparatus 1 may be capable of executing at least one of the belt cleaning operation and the toner discharging operation at any timing without accompanying the image forming operation. In addition, not involving an image forming operation means that it does not involve input of an instruction to start a job to the image forming apparatus 1, and more specifically, it means that a toner image is not formed on the photosensitive drum 3 to be transferred to the recording material S and output.

[0097] In the above embodiment, the belt conveying section 110 (intermediate transfer belt 111) and the belt cleaning device 150 (conveying screw 153) are driven by the same driving source, but they may be driven by different driving sources. In that case, the belt cleaning process and the toner discharging process in the cleaning mode described in the above embodiment may be performed independently. For example, the intermediate transfer unit 100 having the belt conveying section 110 and the belt cleaning device 150 may be detachable from the device main body 2 as a whole, and the belt conveying section 110 and the belt cleaning device 150 may be separated and individually replaceable. In such a configuration, when only the belt conveying section 110 is replaced, only the belt cleaning process may be performed in the cleaning mode. When only the belt cleaning device 150 is replaced, it is desirable to perform the belt cleaning process and the toner discharging process in the cleaning mode so as not to soil the operator or the surrounding environment with the deposits on the surface of the intermediate transfer belt 111.

[0098] Also, as shown in Fig. 14, a configuration is conceivable in which the belt conveying section 110 and the belt cleaning device 150 can be separated inside the apparatus main body 2. Fig. 14 is a schematic diagram of the image forming apparatus 1 as viewed from above. In this case, the belt conveying section 110 and the belt cleaning device 150 can be configured to be replaceable separately according to their respective usage limits. In this case, when the belt conveying section 110 is replaced separately, only the belt cleaning process needs to be performed in the cleaning mode, and when the belt cleaning device 150 is replaced separately, only the toner discharging process needs to be performed in the cleaning mode.

[0099] In addition, it is also possible to replace only the belt after removing the intermediate transfer unit in the above embodiment or the belt transport unit in the above modification from the main body of the apparatus. In this case, too, by executing the belt cleaning mode before removing the intermediate transfer unit or the belt transport unit from the main body of the apparatus, it is possible to obtain the effect of preventing the operator and the surrounding environment from being soiled with toner, as in the above embodiment.

[0100] In addition, the notification of information to the operator, which has been described in the above embodiments as being done by displaying messages or the like, can also be done by emitting light from the light-emitting unit (illuminating or flashing) or by emitting sound from a speaker (warning sound, message, etc.).

[0101] In the above embodiment, the usage limit (life) of the intermediate transfer unit (intermediate transfer belt, belt cleaning device) is set by the number of sheets passed, but is not limited to this. This usage limit can be set by any index value related to the usage amount from the start of use of the intermediate transfer unit (intermediate transfer belt, belt cleaning device). This index value may be a value that correlates with the usage amount of the intermediate transfer unit (intermediate transfer belt, belt cleaning device) accompanying the operation of the image forming apparatus. For example, the print time, the conveying distance (or the number of rotations) or the conveying time (or the rotation time) of the intermediate transfer belt may be used. This is also true for the detection of the usage limit (life) of each of the belt conveying unit 110 and the belt cleaning device 150 in the case where the belt conveying unit 110 and the belt cleaning device 150 are individually replaceable as described above. The usage limit of the intermediate transfer belt and the usage limit of the belt cleaning device 150 can be set individually and detected (storage of accumulated values, comparison with a threshold value, etc.).

[0102] In addition, the image forming apparatus is not limited to an image forming apparatus capable of forming a full-color image, but may be an image forming apparatus capable of forming only a monochrome (black and white or monochromatic) image. For example, the present invention can be applied to a monochrome image apparatus having a configuration in which elements for forming images of yellow, magenta, and cyan are removed from the image forming apparatus of the above embodiment, and the same effects as those of the above embodiment can be obtained. [Explanation of symbols]

[0103] 1. Image forming device 2. Device body 3 Photosensitive drum 100 Intermediate transfer unit 110 Belt conveyor 111 Intermediate transfer belt 114 Primary transfer roller 150 Belt cleaning device 151 Cleaning container 152 Cleaning blade 153 Conveying screw 200 Operation section

Claims

1. an image carrier that carries a toner image; a toner image forming unit that forms a toner image on the surface of the image carrier; a rotatable intermediate transfer belt that is stretched around a plurality of tension rollers and comes into contact with the image carrier to form a transfer section, and onto which a toner image is transferred from the image carrier at the transfer section; a cleaning device for removing toner from the surface of the intermediate transfer belt at a cleaning portion; a belt drive unit that drives and rotates the intermediate transfer belt; A control unit capable of controlling the belt drive unit; An input unit that inputs an instruction based on an operation by an operator to the control unit, an image forming apparatus for performing image formation by transferring a toner image transferred from the image carrier to the intermediate transfer belt, and then transferring the toner image from the intermediate transfer belt to a recording material, a unit including the intermediate transfer belt and the plurality of tension rollers is detachable from a main body of the image forming apparatus, The control unit is capable of controlling the belt drive unit in response to instructions from the input unit when the unit is removed from the device main body, so as to perform a belt cleaning operation in which the intermediate transfer belt is rotated and the cleaning device cleans the surface of the intermediate transfer belt after the final image formation before the removal and prior to the removal, in accordance with instructions from the input unit.

2. a contact / separation mechanism for contacting and separating the intermediate transfer belt with respect to the image carrier; 2 . The image forming apparatus according to claim 1 , wherein the control unit controls the contact / separation mechanism so as to perform the belt cleaning operation in a state in which the intermediate transfer belt is separated from the image carrier.

3. an image carrier driving unit that drives and rotates the rotatable image carrier; 2. The image forming apparatus according to claim 1, wherein the control unit controls the image carrier driving unit to perform the belt cleaning operation while rotating the image carrier against which the intermediate transfer belt is in contact.

4. the toner image forming unit has a rotatable developing member that supplies toner to a surface of the image carrier, and a developing drive unit that drives and rotates the developing member; 4. The image forming apparatus according to claim 3, wherein the control section controls the developing drive section so as to execute the belt cleaning operation while the developing member is stopped.

5. the toner image forming section includes a charging device that charges the image carrier, a charging voltage applying section that applies a charging voltage to the charging device, and a developing voltage applying section that applies a developing voltage to the developing member, 5. The image forming apparatus according to claim 4, wherein the control unit controls the charging voltage application unit and the developing voltage application unit so as to perform the belt cleaning operation without applying the charging voltage to the charging device by the charging voltage application unit and without applying the developing voltage to the developing member by the developing voltage application unit.

6. 2. The image forming apparatus according to claim 1, wherein the control unit controls the toner image forming unit and the belt drive unit so that, after image formation, a predetermined toner image formed on the image carrier is placed between the image carrier and the intermediate transfer belt, and the intermediate transfer belt is stopped in a state in which the intermediate transfer belt is in contact with the image carrier via the predetermined toner image.

7. The image forming apparatus according to claim 6, characterized in that, during the belt cleaning operation, the control unit controls the belt drive unit to rotate the intermediate transfer belt in the rotation direction during image formation at least until the area on the intermediate transfer belt that was in the transfer unit while the intermediate transfer belt was stopped after the final image formation passes through the cleaning unit.

8. 2. The image forming apparatus according to claim 1, wherein the control unit controls the belt drive unit so as to rotate the intermediate transfer belt in a rotation direction during image formation for at least one revolution of the intermediate transfer belt during the belt cleaning operation.

9. Another image carrier that carries a toner image to be transferred to the intermediate transfer belt; Another toner image forming unit forms a toner image on the surface of the other image carrier; a contact / separation mechanism for contacting and separating the intermediate transfer belt with respect to the other image carrier; an image carrier driving unit that drives and rotates the rotatable image carrier; 2. The image forming apparatus according to claim 1, wherein the control unit controls the contact / separation mechanism and the image carrier drive unit to separate the intermediate transfer belt from the other image carrier and perform the belt cleaning operation while rotating the image carrier with which the intermediate transfer belt is in contact.

10. the cleaning device is provided in the unit, is detachable from the device body together with the intermediate transfer belt and the plurality of tension rollers, and includes a cleaning member that removes toner from a surface of the intermediate transfer belt, a cleaning container that contains the toner removed from the surface of the intermediate transfer belt, and a transport member that transports the toner in the cleaning container to be discharged outside the cleaning container; the image forming apparatus includes a cleaning drive unit that drives the conveying member, and a container that contains the toner discharged from the cleaning container; 2. The image forming apparatus according to claim 1, wherein the control unit is capable of controlling the cleaning drive unit to perform a toner discharge operation in which the conveying member is driven to discharge toner from the cleaning container after the final image formation and prior to the removal when the belt cleaning operation is performed.

11. the conveying member is a rotating member that rotates in a first rotation direction during image formation, the cleaning drive unit is capable of rotationally driving the conveying member in the first rotation direction and a second rotation direction opposite to the first rotation direction, 11. The image forming apparatus according to claim 10, wherein the control unit controls the cleaning drive unit so as to rotate the conveying member in the first rotation direction and the second rotation direction during the toner discharging operation.

12. The image forming apparatus according to claim 11, characterized in that the control unit controls the cleaning drive unit so that, during the toner discharging operation, at least one of the rotational speed of the transport member in the first rotational direction or the rotational speed of the transport member in the second rotational direction is faster than the rotational speed of the transport member in the first rotational direction during image formation.

13. 12. The image forming apparatus according to claim 11, wherein the control unit controls the cleaning drive unit so that, during the toner discharging operation, the rotation speed of the conveying member in the second rotation direction is faster than the rotation speed in the first rotation direction.

14. 11. The image forming apparatus according to claim 10, wherein the belt driving section and the cleaning driving section drive and rotate the intermediate transfer belt and the transport member in cooperation with each other by a common driving source.

15. a storage unit for storing usage history information of the intermediate transfer belt; A notification unit that notifies an operator of information, The image forming apparatus according to any one of claims 1 to 14, characterized in that the control unit controls the belt cleaning operation to be performed in response to an instruction from the input unit when the notification unit notifies an operator of information regarding replacement of the unit based on the usage history information.

16. an image carrier that carries a toner image; a toner image forming unit that forms a toner image on the surface of the image carrier; a rotatable intermediate transfer belt that is stretched around a plurality of tension rollers and comes into contact with the image carrier to form a transfer section, and onto which a toner image is transferred from the image carrier at the transfer section; a cleaning device that removes toner from the surface of the intermediate transfer belt at a cleaning section, the cleaning device including a cleaning member that removes toner from the surface of the intermediate transfer belt, a cleaning container that contains the toner removed from the surface of the intermediate transfer belt, and a transport member that transports the toner in the cleaning container to be discharged outside the cleaning container; a cleaning drive unit that drives the conveying member; a container for containing the toner discharged from the cleaning container; a control unit capable of controlling the cleaning drive unit, an image forming apparatus for performing image formation by transferring a toner image transferred from the image carrier to the intermediate transfer belt, and then transferring the toner image from the intermediate transfer belt to a recording material, the cleaning device is detachable from a main body of the image forming apparatus, An image forming apparatus characterized in that, when the cleaning device is removed from the apparatus main body, the control unit is capable of controlling the cleaning drive unit to perform a toner discharge operation of driving the conveying member to discharge toner from the cleaning container after the last image formation before the removal and prior to the removal.

Images