Cleaning device and image forming apparatus

Abstract

To excellently maintain the performance of a cleaning device by suppressing deposition of toner in the cleaning device and re-adhesion of toner to a cleaning member with a simpler structure.SOLUTION: A cleaning device 30 comprises: a first cleaning part 301; a second cleaning part 302; a conveyance member 34 which conveys toner dropped from a first recovery part N1 and a second recovery part N2; and an electrode member 35 which is arranged along the width direction of an image carrier 20, and is opposed to a member that constitutes the first recovery part and a member that constitutes the second recovery part on the side opposite to the image carrier 20 with respect to a member 321 that constitutes the first recovery part N1 and recovers toner by the first recovery part N1 and a member 322 that constitutes the second recovery part N2 and recovers toner by the second recovery part N2. The potential of the electrode member 35 can be set to the potential that generates the electric field in which toner recovered by the second cleaning part 302 heads to the first recovery part N1 side from the electrode member 35 side.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a cleaning device used in an image forming apparatus such as a copying machine, printer, or facsimile machine that uses an electrophotographic or electrostatic recording method, or a multifunction machine that has two or more of these functions, and to an image forming apparatus equipped with the cleaning device. [Background technology]

[0002] In conventional image forming apparatuses using electrophotography or the like, a toner image formed on an image carrier is electrically transferred to a transferee at a transfer unit. Such image forming apparatuses are equipped with a cleaning device for removing toner (transfer residual toner) that remains on the surface of the image carrier without being transferred from the image carrier to the transferee, and unnecessary toner (such as a test toner image) from the surface of the image carrier.

[0003] One known example of such a cleaning device is an electrostatic cleaning device that electrostatically collects toner from an image carrier. This cleaning device includes, for example, a cleaning member that collects positively charged toner, a cleaning member that collects negatively charged toner, a housing, and a transport member that transports the collected toner. Multiple cleaning members are arranged in order in the direction of movement of the image carrier surface, and each electrostatically transfers toner from the image carrier surface to the surface of the cleaning member, removing it from the image carrier surface. The toner collected by the multiple cleaning members is then transported by a single transport member to an outlet provided in the housing. The toner discharged from the outlet is transported to a collected toner box or other container provided in the image forming apparatus.

[0004] As image forming devices become faster and produce higher quality images, they require improved cleaning performance for image carriers. Increasing the number of cleaning members is one way to improve the cleaning performance of cleaning devices. However, if a single transport member is used to transport toner collected from multiple cleaning members (e.g., three), the distance from the most upstream cleaning member to the most downstream cleaning member in the direction of movement of the image carrier surface becomes long. This can lead to toner collected by the most downstream cleaning member scattering within the cleaning device and re-adhering to the cleaning member or accumulating within the housing. Increasing the number of cleaning members to improve the cleaning performance of image carriers increases the toner collection path, potentially causing toner to accumulate within the cleaning device or re-adhere to the cleaning member on its way from the cleaning member to the transport member. This can hinder toner discharge from the cleaning device or reduce cleaning performance. The same applies to cleaning devices with two cleaning members.

[0005] In response to this, Patent Document 1 discloses a configuration in which one cleaning member is provided with one conveying member, thereby preventing the distance from the cleaning member from increasing and preventing the collected toner from re-adhering to the cleaning member. Patent Document 2 also discloses a configuration in which a loosening means is provided on the inner wall surface of the housing, preventing the collected toner from accumulating inside the housing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-233946 [Patent Document 2] Japanese Patent Application Publication No. 2016-218262 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, in the configuration described in Patent Document 1, the same number of conveying members are provided for each cleaning member, thereby suppressing toner scattering within the cleaning device. In addition, in the configuration described in Patent Document 2, a loosening means is provided that oscillates in the axial direction of the conveying member in conjunction with the driving of the conveying member, thereby suppressing toner accumulation within the cleaning device.

[0008] However, in all of these configurations, there are concerns that the cost will increase due to the complexity of the device configuration and the increase in the number of component parts.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to maintain good performance of a cleaning device by suppressing toner accumulation in the cleaning device and toner re-adhesion to a cleaning member with a simpler configuration. [Means for solving the problem]

[0010] The above object is achieved by a cleaning device and an image forming apparatus according to the present invention. In summary, the present invention provides a cleaning device for cleaning the surface of a rotatable image carrier on which a toner image is formed at an image forming position, the cleaning device comprising: a first cleaning unit arranged along a width direction substantially perpendicular to a direction of movement of the surface of the image carrier, the first cleaning member electrostatically removing toner charged to a predetermined polarity from the surface of the image carrier, and a first collection unit dropping and collecting the toner removed from the image carrier by the first cleaning member; a second cleaning member arranged along the width direction downstream of the first cleaning member in the direction of movement of the surface of the image carrier and upstream of the image forming position, the second cleaning member electrostatically removing toner from the surface of the image carrier, and a first collection unit dropping and collecting the toner removed from the image carrier by the second cleaning member; a second cleaning unit having a second collection section that drops and collects toner removed from a carrier; a transport member that transports the toner that has dropped from the first collection section and the second collection section; and an electrode member that is arranged along the width direction and faces the members that constitute the first collection section and the members that constitute the second collection section on the opposite side of the image carrier from the members that constitute the first collection section and from which toner is collected in the first collection section and the members that constitute the second collection section and from which toner is collected in the second collection section, and the potential of the electrode member can be set to a potential that generates an electric field in which the toner collected in the second cleaning unit is directed from the electrode member side to the first collection section side.

[0011] According to another aspect of the present invention, there is provided an image forming apparatus comprising an image carrier, an image forming unit that forms a toner image on the image carrier at an image forming position, and the cleaning device of the present invention. [Effects of the Invention]

[0012] According to the present invention, with a simpler configuration, it is possible to suppress toner accumulation in the cleaning device and toner re-adhesion to the cleaning member, thereby maintaining good performance of the cleaning device. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Figure 2] FIG. 2 is a schematic cross-sectional view for explaining the basic configuration of a cleaning device. [Figure 3] 5A and 5B are schematic diagrams for explaining the movement of toner around an electrode member. [Figure 4] 10 is a graph showing the relationship between electric field strength and toner flying rate. [Figure 5] FIG. 2 is a schematic cross-sectional view illustrating a cleaning device according to an embodiment. [Figure 6] FIG. 10 is a schematic cross-sectional view illustrating a cleaning device according to another embodiment. [Figure 7] FIG. 4 is a schematic diagram illustrating an example of a power supply mode in a cleaning device. [Figure 8] 10A and 10B are schematic diagrams illustrating another example of a power supply mode in the cleaning device. [Figure 9] 10A and 10B are schematic diagrams illustrating another example of a power supply mode in the cleaning device. [Figure 10] 10A and 10B are schematic diagrams illustrating another example of a power supply mode in the cleaning device. DETAILED DESCRIPTION OF THE INVENTION

[0014] The cleaning device and image forming apparatus according to the present invention will be described in more detail below with reference to the drawings.

[0015] [Example 1] 1. Overall configuration and operation of the image forming apparatus 1 is a schematic cross-sectional view of an image forming apparatus 100 according to this embodiment (a cross-section substantially perpendicular to the rotation axis direction of a photosensitive drum 11 and a tension roller for an intermediate transfer belt 20, which will be described later). The image forming apparatus 100 according to this embodiment is a tandem printer that employs an intermediate transfer method.

[0016] Image forming apparatus 100 has four image forming units 1Y, 1M, 1C, and 1K that form images in the colors yellow (Y), magenta (M), cyan (C), and black (K), respectively. The four image forming units 1Y, 1M, 1C, and 1K are arranged in a row along the direction of movement of a substantially horizontally disposed flat portion of intermediate transfer belt 20, which will be described later. Image forming apparatus 100 is capable of forming full-color images on recording material S by electrophotography in response to image signals transmitted from an external device such as a personal computer. Elements in each image forming unit 1Y, 1M, 1C, and 1K that have the same or corresponding functions or configurations may be generally described by omitting the Y, M, C, or K suffix to the reference numerals indicating that the element is for one of the colors. In this embodiment, the image forming unit 1 includes photosensitive drums 11 (11Y, 11M, 11C, 11K), chargers 12 (12Y, 12M, 12C, 12K), exposure devices 13 (13Y, 13M, 13C, 13K), developing devices 14 (14Y, 14M, 14C, 14K), primary transfer rollers 21 (21Y, 21M, 21C, 21K), and drum cleaning devices 15 (15Y, 15M, 15C, 15K), which will be described later. The order (position) of the image forming units for each color is not limited to that of this embodiment. Furthermore, the number of image forming units and the colors of the images to be formed are also not limited to those of this embodiment.

[0017] The photosensitive drum 11, a rotatable drum-type (cylindrical) photosensitive member (electrophotographic photosensitive member) serving as a first image carrier, is driven to rotate at a predetermined peripheral speed (process speed) in the direction of arrow R1 (counterclockwise) in FIG. 1 . The surface of the rotating photosensitive drum 11 is uniformly charged to a predetermined potential of a predetermined polarity (negative in this embodiment) by a charger 12 serving as charging means. During the charging process, a predetermined charging bias (charging voltage) is applied to the charger 12 by a charging power supply (not shown). The charged surface of the photosensitive drum 11 is scanned and exposed by an exposure device (laser scanner) 13 serving as exposure means, and an electrostatic image (electrostatic latent image) is formed on the photosensitive drum 11. The exposure device 13 irradiates the surface of the photosensitive drum 11 with laser light (image light) modulated based on image information from an external device. The electrostatic image formed on the photosensitive drum 11 is developed (visualized) by the developing device 14 as a developing means, which supplies toner as a developer, and a toner image is formed on the photosensitive drum 11. In this embodiment, toner charged with the same polarity as the charge polarity of the photosensitive drum 11 (negative in this embodiment) adheres to the exposed portion (image portion) of the photosensitive drum 11, which has been uniformly charged and then exposed based on image information 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. During the development process, a predetermined development bias (developing voltage) is applied by a development power supply (not shown) to the developing roller, which serves as a developer carrier (developing member) provided in the developing device 14.

[0018] An intermediate transfer belt 20, an intermediate transfer body formed of an endless belt serving as a second image carrier, is disposed facing the four photosensitive drums 11. The intermediate transfer belt 20 is stretched around a plurality of tension rollers 22, 24, 25, 26, 27, 28, and 29 and tensioned with a predetermined tension. A drive roller (e.g., tension roller 25 or tension roller 29), which is one of the tension rollers, is driven to rotate. As a result, the intermediate transfer belt 20 rotates (circularly moves) in the direction of arrow R2 (clockwise) in FIG. 1 at a predetermined peripheral speed (process speed) corresponding to the peripheral speed of the photosensitive drums 11. Another of the tension rollers, an inner secondary transfer roller 22, functions as an opposing member (counter electrode) of an outer secondary transfer roller 23 (described later). The inner secondary transfer roller 22 is electrically grounded (connected to ground). Primary transfer rollers 21Y, 21M, 21C, and 21K, which are roller-type primary transfer members serving as primary transfer means, are arranged on the inner circumferential surface of the intermediate transfer belt 20, corresponding to the photosensitive drums 11Y, 11M, 11C, and 11K, respectively. In this embodiment, the primary transfer rollers 21 are arranged at positions where they contact the photosensitive drums 11 via the intermediate transfer belt 20. The primary transfer rollers 21 are pressed against the photosensitive drums 11 and contact the photosensitive drums 11 via the intermediate transfer belt 20, forming a primary transfer portion (primary transfer nip, image forming position) T1 where the photosensitive drums 11 and the intermediate transfer belt 20 come into contact. The tension rollers other than the drive roller among the multiple tension rollers, and each primary transfer roller 21, are rotated in accordance with the rotation of the intermediate transfer belt 20. The toner image formed on the photosensitive drum 11 is transferred (primary transfer) onto the rotating intermediate transfer belt 20 at the primary transfer portion T1 by the action of the primary transfer rollers 21. During the primary transfer process, a primary transfer bias (primary transfer voltage), which is a DC voltage of opposite polarity (positive polarity in this embodiment) to the normal charging polarity of the toner, is applied to the primary transfer roller 21 by a primary transfer power supply (high-voltage power supply) not shown. This supplies a primary transfer current to the primary transfer portion T1. For example, when forming a full-color image, the toner images of yellow, magenta, cyan, and black formed on each photosensitive drum 11 are sequentially primary-transferred so as to be superimposed on the same image position (image area) on the intermediate transfer belt 20.

[0019] On the outer peripheral surface of the intermediate transfer belt 20, a secondary transfer outer roller 23, which is a roller-type secondary transfer member serving as a secondary transfer means, is disposed at a position facing the inner secondary transfer roller 22. The outer secondary transfer roller 23 is pressed against the inner secondary transfer roller 22 and abuts against the inner secondary transfer roller 22 via the intermediate transfer belt 20, forming a secondary transfer portion (secondary transfer nip) T2 where the intermediate transfer belt 20 and the outer secondary transfer roller 23 come into contact. At the secondary transfer portion T2, the toner image formed on the intermediate transfer belt 20 is transferred (secondarily transferred) onto a recording material (transfer material, recording medium, sheet) S, which is being conveyed while being sandwiched between the intermediate transfer belt 20 and the outer secondary transfer roller 23, by the action of the outer secondary transfer roller 23. During the secondary transfer process, a secondary transfer bias (secondary transfer voltage), which is a DC voltage of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment), is applied to the outer secondary transfer roller 23 by a secondary transfer power supply (high-voltage power supply) not shown. This supplies a secondary transfer current to the secondary transfer portion T2. ​​Recording material S, such as paper or plastic sheets, is stored in cassettes 61 and 62 serving as recording material storage portions. The recording material S is fed one sheet at a time from either cassette 61 or 62 to a feeding path 81 by the rotation of either feed roller 71 or 72 serving as a feeding member. The recording material S is then conveyed to the secondary transfer portion T2 by a registration roller 74 serving as a conveying member, synchronized with the toner image on the intermediate transfer belt 20. The position and number of recording material storage portions are not limited to those in this embodiment. Alternatively, a roller corresponding to the inner secondary transfer roller 22 in this embodiment may be used as a secondary transfer member, and a secondary transfer bias of the opposite polarity (the same polarity as the normal charging polarity of the toner) may be applied to it. In this case, a roller corresponding to the outer secondary transfer roller 23 in this embodiment may be used as a counter member (counter electrode) and electrically grounded.

[0020] The recording material S onto which the toner image has been transferred is conveyed to a fixing device (thermal fixing device) 5 as fixing means. The fixing device 5 applies heat and pressure (thermocompression) to the recording material S carrying the unfixed toner image, thereby fixing (melting and solidifying) the toner image onto the recording material S. The recording material S onto which the toner image has been fixed passes through a discharge conveyance path 82 and is discharged (output) to a discharge tray 64 provided outside the main body of the image forming apparatus 100.

[0021] Furthermore, deposits such as toner (primary transfer residual toner) remaining on the photosensitive drum 11 without being transferred to the intermediate transfer belt 20 are removed and collected by a drum cleaning device 15 serving as a photosensitive body cleaning means. Also, deposits such as toner (secondary transfer residual toner) remaining on the intermediate transfer belt 20 without being transferred to the recording material S and unnecessary toner (such as a test toner image) are removed and collected from the intermediate transfer belt 20 by a cleaning device (belt cleaning device) 30 serving as an intermediate transfer body cleaning means. The cleaning device 30 will be described in more detail later.

[0022] In this embodiment, the intermediate transfer belt 20 is a multi-layer belt having a base layer (backside layer), an elastic layer (middle layer), and a surface layer. The base layer is made of a material such as a resin, such as polyimide or polycarbonate, or various rubbers, containing an appropriate amount of carbon black as an antistatic agent. The elastic layer is made of a material such as various rubbers, such as CR rubber, urethane rubber, or silicone rubber, containing an appropriate amount of an ion conductive agent. Examples of ion conductive agents include aliphatic sulfonates. The surface layer is made of a resin, such as a urethane resin or fluororesin. In this embodiment, the intermediate transfer belt 20, the multiple tension rollers, each primary transfer roller 21, and the cleaning device 30 integrally constitute an intermediate transfer unit that is detachable from the main body of the image forming apparatus 100.

[0023] 2.Cleaning device Next, a cleaning device (belt cleaning device) 30 in this embodiment will be described. In this embodiment, the present invention is applied to a cleaning device 30 equipped with three cleaning members, which makes the effect of the present invention more pronounced. However, to facilitate understanding of the principles of the present invention, the basic configuration of a cleaning device 30 according to the present invention will first be described using an example of a configuration equipped with two cleaning members.

[0024] <Basic configuration> 2 is a schematic cross-sectional view (a cross-section substantially perpendicular to the rotation axis direction of the photosensitive drum 11 and the tension roller of the intermediate transfer belt 20) of the vicinity of the cleaning device 30. The cleaning device 30 is disposed downstream of the secondary transfer portion T2 and upstream of the primary transfer portion T1 (the most upstream primary transfer portion T1Y) in terms of the movement direction (rotation direction, conveyance direction) of the surface of the intermediate transfer belt 20.

[0025] Note that, here, positions such as upstream (most upstream), downstream (most downstream), and center with respect to the cleaning device 30 and its elements refer to positions relative to the moving direction of the surface of the intermediate transfer belt 20, unless otherwise specified. Furthermore, with respect to the image forming apparatus 100 and its elements, the front side of the paper in FIG. 1 is referred to as the front (front) side, and the back side of the paper in FIG. 1 is referred to as the rear (rear) side. The front-to-rear direction (depth direction) connecting the front and rear sides of the image forming apparatus 100 is assumed to be approximately parallel to the direction of the rotation axis of the tension roller of the photosensitive drum 11 or the intermediate transfer belt 20 (a direction approximately perpendicular to the moving direction of the surface of the photosensitive drum 11 or the intermediate transfer belt 20). Furthermore, with respect to the image forming apparatus 100 and its elements, the up-down direction refers to the up-down direction relative to the direction of gravity (vertical direction), but does not mean only directly above or directly below, but also includes above and below a horizontal plane passing through a position or element of interest.

[0026] In this embodiment, the cleaning device 30 is an electrostatic cleaning device that electrostatically collects toner and other adhering matter on the intermediate transfer belt 20. The cleaning device 30 removes adhering matter, such as secondary transfer residual toner, remaining on the intermediate transfer belt 20 after the secondary transfer. The cleaning device 30 is also used to remove unnecessary toner images, such as test toner images and toner images remaining after jamming, from the intermediate transfer belt 20. In this embodiment, the cleaning device 30 includes a plurality of cleaning members that are arranged to contact a plurality of tension rollers that tension the intermediate transfer belt 20 and each of which has the intermediate transfer belt 20 interposed therebetween, and electrostatically moves the transfer residual toner and unnecessary toner images on the intermediate transfer belt 20 onto the cleaning members for removal.

[0027] The cleaning device 30 shown in FIG. 2 includes a first cleaning unit 301 and a second cleaning unit 302, which are arranged adjacent to each other in order from the upstream side to the downstream side in the moving direction of the surface of the intermediate transfer belt 20. The cleaning device 30 also includes a transport member 34 that transports the toner collected by each cleaning unit 301, 302 to an outlet (not shown) provided in a housing 36 (described later). The cleaning device 30 also includes an electrode member 35 (described later). The cleaning device 30 also includes a housing 36 that houses the cleaning units 301, 302, the transport member 34, and the electrode member 35. The transport member 34 is positioned below all of the cleaning units to transport the toner scraped off by each cleaning unit. The transport member 34 is configured by a screw or the like that transports the toner along the front-to-rear direction of the cleaning device 30, for example, from front to rear.

[0028] The first cleaning unit 301 includes a first cleaning member 311 that contacts a first tension roller 24, which is one of the tension rollers of the intermediate transfer belt 20, via the intermediate transfer belt 20, a first collection member 321, and a first scraping member 331. The second cleaning unit 302 includes a second cleaning member 312 that contacts a second tension roller 25, which is one of the tension rollers of the intermediate transfer belt 20, via the intermediate transfer belt 20, a second collection member 322, and a second scraping member 332.

[0029] In the first and second cleaning units 301 and 302, first and second cleaning members 311 and 312, respectively, electrostatically transfer toner on the intermediate transfer belt 20 to the surfaces of the cleaning members 311 and 312, thereby removing the toner from the intermediate transfer belt 20. Thereafter, the first and second cleaning units 301 and 302 electrostatically transfer the toner to the surfaces of first and second collection members 321 and 322, which rotate opposite the first and second cleaning members 311 and 312, respectively. Thereafter, the first and second cleaning units 301 and 302 scrape the toner from the first and second collection members 321 and 322 using first and second scraping members 331 and 332, which are arranged to rub against the surfaces of the first and second collection members 321 and 322, respectively. The toner scraped in this manner falls toward the conveying member 34 (falls toward the bottom of the housing 35 in which the conveying member 34 is provided). Here, the contact position between the first collection member 321 and the first scraping member 331 is referred to as a first collection position (first collection section) N1, and the contact position between the second collection member 322 and the second scraping member 332 is referred to as a second collection position (second collection section) N2. Similarly, the contact position between the third collection member 323 (or the third cleaning member 313) described below and the third scraping member 333 is referred to as a third collection position (third collection section) N3.

[0030] The first and second cleaning members 311 and 312 (and the third cleaning member 313 described later) are preferably brush rollers having a rotatably supported metal rotating shaft and a plurality of raised bristles made of conductive fibers arranged on the circumferential surface of the rotating shaft. However, depending on the amount of toner to be removed and other conditions, the first and second cleaning members 311 and 312 (and the third cleaning member 313 described later) may also be conductive rubber rollers or sponge rollers having an elastic layer made of conductive rubber or sponge on the circumferential surface of the rotating shaft. In this embodiment, brush rollers are used as the first and second cleaning members 311 and 312 (and the third cleaning member 313 described later). In other words, in this embodiment, rotatable roller-shaped conductive fur brushes (conductive fur brush rollers) are used as the first and second cleaning members 311 and 312 (and the third cleaning member 313 described later). The first and second cleaning members 311 and 312 (and a third cleaning member 313 described later) are each driven to rotate in the direction of arrow R3 in the drawing (clockwise direction) by a drive motor (not shown) serving as a drive unit. That is, the first and second cleaning members 311 and 312 (and a third cleaning member 313 described later) rotate so as to move in the opposite direction to the movement direction of the intermediate transfer belt 20 at the contact portion with the intermediate transfer belt 20, thereby rubbing the surface of the intermediate transfer belt 20. The first and second cleaning members 311 and 312 (and a third cleaning member 313 described later) are disposed such that their rotation axes are substantially parallel to a direction substantially perpendicular to the movement direction of the surface of the intermediate transfer belt 20. In this embodiment, the length of the rotation axes of the first and second cleaning members 311 and 312 (and a third cleaning member 313 described later) is substantially equal to or shorter than the width of the intermediate transfer belt 20 (the length in the direction substantially perpendicular to the movement direction of the surface). The length of the first and second cleaning members 311 and 312 (and the third cleaning member 313 described later) in the direction of their rotational axes may be longer than the maximum image formation width on the intermediate transfer belt 20 in a direction approximately perpendicular to the direction of movement of the surface of the intermediate transfer belt 20.

[0031] Metal rollers are preferably used as the first and second collection members 321, 322 (and the third collection member 323 described later). In this embodiment, metal rollers are used as the first and second collection members 321, 322 (and the third collection member 323 described later). The first and second collection members 321, 322 (and the third collection member 323 described later) are each driven to rotate in the direction of arrow R4 in the drawing (counterclockwise) by a drive motor (not shown) serving as a drive means. In other words, the first and second collection members 321, 322 (and the third collection member 323 described later) rotate so as to move in the same direction as the movement of the first and second cleaning members 311, 312 (and the third cleaning member 313 described later) at their contact portions with the first and second cleaning members 311, 312 (and the third cleaning member 313 described later). The first and second recovery members 321 and 322 (and a third recovery member 323, which will be described later) are arranged such that their rotational axis direction is substantially parallel to a direction substantially perpendicular to the moving direction of the surface of the intermediate transfer belt 20. In this embodiment, the length in the rotational axis direction of the first and second recovery members 321 and 322 (and a third recovery member 323, which will be described later) is substantially equal to or longer than the length in the rotational axis direction of the first and second cleaning members 311 and 312 (and a third cleaning member 313, which will be described later).

[0032] The first and second scraping members 331, 332 (and the third scraping member 333 described later) are desirably elastic blade members formed from rubber, a PET sheet, or the like. The first and second scraping members 331, 332 (and the third scraping member 333 described later) are arranged in contact with the first and second collection members 321, 322 (and the third collection member 323 described later), respectively. The first and second scraping members 331, 332 (and the third scraping member 333 described later) have predetermined lengths and thicknesses in the longitudinal direction, which is approximately parallel to the rotational axis direction of the first and second collection members 321, 322 (and the third collection member 323 described later), and in the lateral direction, which is approximately perpendicular to the longitudinal direction. The first and second scraping members 331, 332 (and the third scraping member 333 described later) are abutted against the respective recovery members so as to be in the counter direction (the direction in which the free ends face upstream in the rotation direction) with respect to the rotation direction of the first and second recovery members 321, 322 (and the third recovery member 323 described later). In this embodiment, the longitudinal lengths of the first and second scraping members 331, 332 (and the third scraping member 333 described later) are approximately equal to or shorter than the length in the rotational axis direction of the first and second recovery members 321, 322 (and the third recovery member 323 described later).

[0033] Furthermore, the cleaning device 30 according to the present invention is provided with an electrode member 35 at a position facing the first recovery member 321 and the second recovery member 322 on the opposite side from the first cleaning member 311 and the second cleaning member 312 and the intermediate transfer belt 20. The electrode member 35 is made of a conductive material. In this embodiment, the electrode member 35 is made of a metal material such as stainless steel (SUS) or aluminum, but may also be made of a conductive resin material. In this embodiment, the housing 36 of the cleaning device 30 (excluding the electrode member 35) is made of an electrically insulating resin material. The electrode member 35 has a length in the front-rear direction of the cleaning device 30 that is approximately equal to the lengths of the first recovery member 321 and the second recovery member 322. Here, "approximately equal to the lengths of the first recovery member 321 and the second recovery member 322" typically means a length that is 70% to 130%, preferably 90% to 110%, of the lengths of the first recovery member 321 and the second recovery member 322, which are defined as 100%. The shorter ones are arranged inside the longer ones. The position of the upper end of the electrode member 35 is set so that the electrode member 35 is arranged at a position where it overlaps at least the second recovery member 322 in the vertical direction. The position of the upper end of the electrode member 35 is preferably at least opposite the second recovery position N2 or at a position higher than that position (at the same height as the second recovery position N2 or at a position higher than the second recovery position N2). The position of the lower end of the electrode member 35 will be described later in the description of the specific configuration of each embodiment.

[0034] 3 is a schematic diagram illustrating the movement of toner around the electrode member 35. When the toner collected by the second cleaning unit 302 is negative, the potential of the electrode member 35 is set lower than the potential of the first recovery member 321 (so as to be more negative than the potential of the first recovery member 321). Conversely, when the toner collected by the second cleaning unit 302 is positive, the potential of the electrode member 35 is set higher than the potential of the first recovery member 321 (so as to be more positive than the potential of the first recovery member 321). This creates an electric field such that the toner scraped from the second recovery member 322 by the second scraping member 332 is subjected to a force from the electrode member 35 toward the first recovery member 321. The toner scraped from the second recovery member 322 by the second scraping member 332 is subjected to a force due to the charge of the toner and the electric field, and is more likely to fly toward the first recovery member 321 than toward the electrode member 35. Therefore, the toner falls directly toward the conveying member 34 or adheres to the first recovery member 321. The toner adhering to the first recovery member 321 is then scraped off by the first scraping member 331 and falls toward the conveying member 34.

[0035] Toner flies while being influenced by the charge of the toner and the electric field. Figure 4 shows the flying rate of toner with a mass-to-charge ratio of about -20 to -200 kg / C. From this figure, it can be seen that the stronger the electric field strength, the easier the toner is to fly. Also, from this figure, when the electric field strength is 0.5 x 10 7 When the electric field strength is 0.8×10 V / m or more, it becomes easier for the particles to fly. 7 V / m~1.4×10 7 It can be seen that the toner flies sufficiently when the electric field strength is about 0.5×10 V / m. However, if the electric field strength becomes too large, discharge is likely to occur between the electrodes. If a discharge occurs, the charge polarity of the toner may change, making it difficult to achieve the desired effect. From the above, it can be seen that the electric field strength E between the electrode member 35 and the first recovery member 321 is about 0.5×10 7 <E<1.4×10 7 It is desirable to determine and arrange the potential of the electrode member 35 so that the potential is [V / m].

[0036] In order to generate this electric field over almost the entire area of ​​the first recovery member 321 and the second recovery member 322 in the front-to-back direction of the cleaning device 30, it is desirable that the length (width) of the electrode member 35 in the front-to-back direction be approximately equal to the length (width) of the first recovery member 321 and the second recovery member 322 in the front-to-back direction.

[0037] Furthermore, it is desirable to position the first scraping member 331 downstream in the rotation direction of the first recovery member 321 from the position where the first scraping member 331 is exposed below the second recovery position N2 and upstream in the rotation direction of the first recovery member 321 from the contact position between the first recovery member 321 and the first cleaning member 311. More specifically, it is desirable to position the first scraping member 331 in a position where it is hidden below the first recovery member 321 with respect to the second recovery position N2 (a position below a horizontal plane passing through the rotation center of the first recovery member 321). This ensures that even if toner scraped by the second scraping member 332 adheres to the first recovery member 321, it can be more effectively scraped off by the first scraping member 311. Note that in order to receive the toner scraped by the second scraping member 332 over a wider range in the circumferential direction of the first recovery member 321, it is desirable to rotate the first recovery member 321 in the opposite direction to the rotation direction of the intermediate transfer belt 20 (in terms of the movement direction at the opposing position).

[0038] The action of the electrode member 35 as described above can prevent the collected toner from accumulating inside the housing 36 (particularly on the inner wall at the position corresponding to the electrode member 35). This can prevent the collected toner from clogging the inside of the cleaning device 30 and the collected toner from re-adhering to the cleaning members 311 and 312.

[0039] Here, the electrode member 35 can be provided so as to constitute a part of the housing 36. In other words, the electrode member 35 can constitute at least a part of the wall of the housing 36 (the electrode member 35 can be arranged so as to cover the opening of the frame that constitutes the housing 36). This makes it possible to reduce the size of the cleaning device 30 and the number of component parts.

[0040] <Specific Configuration of this Example> 5 is a schematic cross-sectional view (a cross-section substantially perpendicular to the rotation axis direction of the photosensitive drum 11 and the tension roller of the intermediate transfer belt 20) of the vicinity of the cleaning device 30 of this embodiment. In this embodiment, a third cleaning unit 303 is provided adjacent to the upstream side of the first cleaning unit 301 in the moving direction of the surface of the intermediate transfer belt 20. In the cleaning device 30 of this embodiment shown in FIG. 5, elements having the same or corresponding functions or configurations as those of the cleaning device 30 shown in FIG. 2 above will be assigned the same reference numerals and descriptions thereof will be omitted as appropriate (the same applies to other embodiments described later).

[0041] In this embodiment, the first cleaning unit 301 and the second cleaning unit 302 collect negative toner, and the third cleaning unit 303 collects positive toner.

[0042] FIG. 7 is a schematic diagram illustrating a method for supplying power to the cleaning unit in this embodiment. In this embodiment, to electrostatically move negative toner on the intermediate transfer belt 20 to the first cleaning member 311 and the second cleaning member 312, a positive voltage is applied to the first collection member 321 and the second collection member 322, and the first tension roller 24 and the second tension roller 25 are electrically grounded. That is, in this embodiment, a cleaning bias (cleaning voltage), which is a positive DC voltage, is applied to the first collection member 321 and the second collection member 322 from the first cleaning power source E1 and the second cleaning power source E2, respectively. Note that a positive voltage may be applied directly to at least one of the first cleaning member 311 and the second cleaning member 312, rather than to the first collection member 321 and the second collection member 322.

[0043] The third cleaning unit 303 includes a third cleaning member 313 that contacts the third tension roller 26, which is one of the tension rollers for the intermediate transfer belt 20, via the intermediate transfer belt 20, a third collection member 323, and a third scraping member 333. In the configuration of this embodiment shown in FIG. 5, the drive roller for the intermediate transfer belt 20 is the second tension roller 25, which allows the number of components of the image forming apparatus 100 to be reduced.

[0044] 7, in this embodiment, in order to electrostatically move positive toner on the intermediate transfer belt 20 to the third cleaning member 313, a positive voltage is applied to the third tension roller 26, and the third collection member 323 is electrically grounded. That is, in this embodiment, a cleaning bias (cleaning voltage), which is a positive DC voltage, is applied to the third tension roller 26 from the third cleaning power source E3. Note that the third cleaning member 313 may be electrically grounded directly, instead of the third collection member 323. The toner on the third cleaning member 313 is electrostatically moved onto the third collection member 323 and scraped off by a third scraping member 333 that is arranged to rub against the surface of the third collection member 323.

[0045] 6, third collection member 323 may be omitted and third scraping member 333 may be disposed so as to rub against the surface of third cleaning member 313. In this case, a positive voltage is applied to third tension roller 26, and third cleaning member 313 is electrically grounded. Similarly, a configuration may be envisaged in which first scraping member 331 and second scraping member 332 are disposed so as to collect toner from first cleaning member 311 and second cleaning member 312, without providing first collection member 321 and second collection member 322.

[0046] The toner scraped off by the third scraping member 333 falls toward the conveying member 34 and is conveyed by the conveying member 34 to an outlet provided in the housing 36 together with the toner collected by the first cleaning section 301 and the second cleaning section 302.

[0047] In this embodiment, the electrode member 35 is electrically grounded. This creates an electric field that applies a force from the electrode member 35 to the second and first collection members 322 and 321 to negatively charged toner. Meanwhile, because the electrode member 35 and the third collection member 323 (or the third cleaning member 313) are both grounded, no electric field is formed between them. Both the positive toner collected by the third cleaning member 313 and the negative toner collected by the second and first cleaning members 312 and 311 fall toward the conveying member 34 without being affected by the electric field. Therefore, in this embodiment, the lower end of the electrode member 35 may extend below the third collection position N3, such as to the lower end of the interior of the cleaning device 30. The lower end of the electrode member 35 is positioned so that the electrode member 35 overlaps at least the first collection member 321 in the vertical direction. Therefore, in this embodiment, the position of the lower end of the electrode member 35 is typically set to a position between the first collection position N1 and the lower end inside the cleaning device 30 (a position below the third collection position N3).

[0048] The polarity of the toner collected by each cleaning unit may be reversed from that in this embodiment, with the first cleaning unit 301 and the second cleaning unit 302 collecting positive toner and the third cleaning unit collecting negative toner. In this case, the above description can be understood by replacing positive with negative and negative with positive.

[0049] Here, the electric field between the electrode member 35 and the cleaning unit according to the present invention only needs to be formed at least during the image forming operation (more specifically, during cleaning of secondary transfer residual toner during the image forming operation). Therefore, for example, there may be a period during which an electric field having a different relationship from the above electric field is formed, or a period during which no electric field is formed, such as during preparatory operations or adjustment operations of the image forming apparatus 100. Furthermore, the power sources E1, E2, and E3 (and E10, described later) for setting the above electric fields can be controlled by a control unit 150 (FIG. 1) provided in the image forming apparatus 100.

[0050] As described above, in this embodiment, the cleaning device 30 that cleans the surface of the rotatable image carrier 20 on which a toner image is formed at the image forming position T1 includes a first cleaning unit 301 that is arranged along the width direction substantially perpendicular to the direction of movement of the surface of the image carrier 20 and includes a first cleaning member 311 that electrostatically removes toner charged to a predetermined polarity from the surface of the image carrier 20 and a first collection unit N1 that drops and collects the toner removed from the image carrier 20 by the first cleaning member 311; a second cleaning member 312 that is arranged along the width direction downstream of the first cleaning member 311 in the direction of movement of the surface of the image carrier 20 and upstream of the image forming position T1 and electrostatically removes toner from the surface of the image carrier 20; 20 and collects the toner removed from the second cleaning section 302; a transport member 34 that transports the toner that has dropped from the first recovery section N1 and the second recovery section N2; and an electrode member 35 that is arranged along the width direction and faces the member 321 that constitutes the first recovery section N1 and the member 322 that constitutes the second recovery section N2 on the opposite side of the image carrier 20 from the member (first recovery member) 321 that constitutes the first recovery section N1 and from which the toner is collected in the first recovery section N1 and the member (second recovery member) 322 that constitutes the second recovery section N2 and from which the toner is collected in the second recovery section N2, and the potential of the electrode member 35 can be set to a potential that generates an electric field in which the toner collected in the second cleaning section N2 is directed from the electrode member side to the first recovery section side. In this embodiment, the first cleaning unit 301 includes a first recovery member 321 that electrostatically recovers toner from the first cleaning member 311 and a first scraping member 331 that contacts the first recovery member 321 to form a first recovery portion N1 on the first recovery member, while the second cleaning unit 302 includes a second recovery member 322 that electrostatically recovers toner from the second cleaning member 312 and a second scraping member 332 that contacts the second recovery member 322 to form a second recovery portion N2 on the second recovery member, and the electrode member 35 faces the first recovery member 321 and the second recovery member 322 on the side opposite to the image carrier 20. In this embodiment, the widthwise length of the electrode member 35 is approximately equal to the widthwise lengths of the first recovery member 321 and the second recovery member 322.

[0051] In addition, in this embodiment, the cleaning device 30 is arranged along the width direction downstream of the image forming position T1 and upstream of the first cleaning member 311 in the movement direction of the surface of the image carrier 20, and includes a third cleaning unit 303 equipped with a third cleaning member 313 that electrostatically removes toner from the surface of the image carrier 20 and a third collection unit N3 that drops and collects the toner removed from the image carrier 20 by the third cleaning member 313, the second cleaning member 312 electrostatically removes toner charged to the predetermined polarity from the surface of the image carrier 20, the third cleaning member 313 electrostatically removes toner charged to the polarity opposite to the predetermined polarity from the surface of the image carrier 20, the transport member 34 transports the toner that has dropped from the first collection unit N1, the second collection unit N2, and the third collection unit N3, and the member (third collection member) 323 that constitutes the third collection unit N3 and from which toner is collected in the third collection unit N3 and the electrode member 35 are electrically grounded. In this embodiment, the lower end of the electrode member 35 is located below the third collection portion N3. In this embodiment, a voltage of a polarity opposite to the predetermined polarity is applied to the member 321 constituting the first collection portion N1 and the member 322 constituting the second collection portion N2. In this embodiment, the third cleaning portion 301 includes a third collection member 323 that electrostatically collects toner from the third cleaning member 313 and a third scraping member 333 that contacts the third collection member 323 to form the third collection portion N3 on the third collection member. The third cleaning portion 301 may also include a third scraping member 333 that contacts the third cleaning member 313 to form the third collection portion N3 on the third cleaning member. In this embodiment, the electrode member 35 forms part of the housing of the cleaning device 30. This embodiment provides an image forming apparatus 100 including an image carrier 20, an image forming unit 1 that forms a toner image on the image carrier 20 at an image forming position T1, and the cleaning device 30.

[0052] As described above, in this embodiment, an electrode member is disposed opposite the image carrier and facing the cleaning member, creating an electric field that causes the collected toner to be subjected to a force from the electrode member toward the cleaning member. This allows the collected toner to fall toward the conveying member 34 without accumulating within the cleaning device 30. This embodiment can prevent toner accumulation within the cleaning device 30 and toner re-adhesion to the cleaning members 311, 312, and 313. Furthermore, it is possible to effectively convey collected toner to the multiple cleaning members 311, 312, and 313 using a single conveying member 34. Therefore, this embodiment can effectively maintain the performance of the cleaning device 30 by preventing toner accumulation within the cleaning device 30 and toner re-adhesion to the cleaning members 311, 312, and 313 with a simpler configuration.

[0053] [Example 2] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are assigned the same reference numerals as those of embodiment 1, and detailed descriptions thereof will be omitted.

[0054] In this embodiment, the polarity of the toner collected by each cleaning section of the cleaning device 30 is the same as in Example 1, but the potential of the electrode member 35 is different from that in Example 1. This embodiment also describes another example of a method of supplying power to the cleaning section. Figure 8 is a schematic diagram for explaining the method of supplying power to the cleaning section in this embodiment.

[0055] The following methods can be used to electrostatically move negative toner on the intermediate transfer belt 20 to the first cleaning member 311 and the second cleaning member 312. That is, as in the first embodiment, a positive voltage can be applied to the first collection member 321 and the second collection member 322, and the first tension roller 24 and the second tension roller 25 can be electrically grounded. Note that a positive voltage can be applied directly to at least one of the first cleaning member 311 and the second cleaning member 312, rather than to the first collection member 321 and the second collection member 322. Another method is to apply a negative voltage to the first tension roller 24 and the second tension roller 25, and electrically ground the first collection member 321 and the second collection member 322. Note that at least one of the first cleaning member 311 and the second cleaning member 312, rather than to the first collection member 321 and the second collection member 322, can be electrically grounded. Any of these methods may be used, and different methods may be used for the first cleaning unit 301 and the second cleaning unit 302. Here, the case where the method of supplying power to the first and second cleaning units 301 and 302 is the same as in the first embodiment will be taken as an example.

[0056] The following methods can be used as a means for electrostatically moving the positive toner on the intermediate transfer belt 20 to the third cleaning member 313. That is, as in the first embodiment, a positive voltage can be applied to the third tension roller 26 and the third collection member 323 can be electrically grounded. Note that the third cleaning member 313 can also be electrically grounded directly, instead of the third collection member 323. Another method is to apply a negative voltage to the third collection member 323 and electrically ground the third tension roller 26. Note that a negative voltage can also be applied directly to the third cleaning member 313, instead of the third collection member 323. Either of these methods can be used. Here, the case where the power supply method to the third cleaning unit 303 is the same as in the first embodiment is taken as an example.

[0057] 6, the third collection member 323 may be omitted and the third scraping member 333 may be disposed so as to rub against the surface of the third cleaning member 313. In this case, a positive voltage may be applied to the third tension roller 26, and the third cleaning member 313 may be electrically grounded, as in the case of the first embodiment. Alternatively, a negative voltage may be applied to the third cleaning member 313, and the third tension roller 26 may be electrically grounded.

[0058] In this embodiment, a negative voltage is applied to the electrode member 35 so that its potential is lower than that of the first collection member 321 and the third collection member 323 (or the third cleaning member 313). That is, in this embodiment, an electrode member bias (electrode member voltage), which is a negative DC voltage, is applied to the electrode member 35 from the electrode member power supply E10. This creates an electric field in which negatively charged toner is subjected to a force from the electrode member 35 toward the second collection member 322 and the first collection member 321. The negatively charged toner scraped from the second collection member 322 by the second scraping member 332 flies toward the first collection member 321 rather than the electrode member 35. In addition, an electric field is created in which the negatively charged toner scraped from the first collection member 321 by the first scraping member 331 is also subjected to a force from the electrode member 35 toward the third collection member 323 (or the third cleaning member 313). The toner scraped by first scraping member 331 flies as described above, and therefore falls directly toward conveying member 34 without accumulating on electrode member 35, or adheres to third collection member 323 (or third cleaning member 313), is scraped by third scraping member 333, and falls toward conveying member 34. In this way, toner collected from a plurality of cleaning units can be conveyed by common conveying member 34 to an outlet provided in housing 36, without toner accumulating on electrode member 35.

[0059] In this embodiment, the toner collected by the third cleaning member 313 has an opposite polarity to the toner scraped by the first scraping member 331. Therefore, the toner collected by the third cleaning member 313 is affected by the electric field, such that the toner is subjected to a force from the third collection member 323 (or the third cleaning member 313) toward the electrode member 35. Therefore, in this embodiment, in order to apply the effect of the electric field formed by the electrode member 35 and the third collection member 323 (or the third cleaning member 313) substantially only to the toner scraped by the first scraping member 331, it is desirable to set the position of the lower end of the electrode member 35 as follows. That is, in this embodiment, it is desirable that the lower end of the electrode member 35 does not extend below the third collection position N3, which is the contact position between the third collection member 323 (or the third cleaning member 313) and the third scraping member 333. Furthermore, the position of the lower end of the electrode member 35 is set so that the electrode member 35 is positioned so that it overlaps at least the first collection member 321 in the vertical direction. Therefore, in this embodiment, the position of the lower end of the electrode member 35 is typically set to a position between the first collection position N1 and a position above the third collection position N3.

[0060] As described above, in this embodiment, the first cleaning member 311 and the second cleaning member 312 electrostatically remove toner charged to a predetermined polarity from the surface of the image carrier 20, the third cleaning member 313 electrostatically remove toner charged to a polarity opposite to the predetermined polarity from the surface of the image carrier 20, the transport member 34 transports toner that has fallen from the first collection section N1, the second collection section N2, and the third collection section N3, a voltage of the predetermined polarity is applied to the electrode member 35, and the lower end of the electrode member 35 is located above the third collection section N3. Also, in this embodiment, the member (third collection member) 323 that constitutes the third collection section N3 and collects toner in the third collection section is electrically grounded.

[0061] The polarity of the toner collected by each cleaning unit may be reversed from that in this embodiment, with the first cleaning unit 301 and the second cleaning unit 302 collecting positive toner and the third cleaning unit collecting negative toner. In this case, the above description can be understood by replacing positive with negative and negative with positive, and reinterpreting the high and low potentials.

[0062] [Example 3] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are assigned the same reference numerals as those of embodiment 1, and detailed descriptions thereof will be omitted.

[0063] In this embodiment, the polarity of the toner collected by each cleaning unit of the cleaning device 30, the description of the first cleaning unit 301 and the second cleaning unit 302, and the potential of the electrode member 35 are the same as in Example 1. In this embodiment, the conditions for the third cleaning unit 303 are different from those in Example 1. Figure 9 is a schematic diagram for explaining the method of supplying power to the cleaning units in this embodiment.

[0064] In this embodiment, a negative voltage is applied to the third collection member 323 and the third tension roller 26 is electrically grounded in order to electrostatically move the positive toner on the intermediate transfer belt 20 to the third cleaning member 313. Note that a negative voltage may be applied directly to the third cleaning member 313 instead of the third collection member 323.

[0065] 6, the third scraping member 333 may be disposed so as to rub against the surface of the third cleaning member 313, without providing the third collection member 323. In this case, in this embodiment, a negative voltage is applied to the third cleaning member 313, and the third tension roller 26 is electrically grounded.

[0066] In this embodiment, the electrode member 35 is electrically grounded, as in the first embodiment. This creates an electric field that causes negatively charged toner to be subjected to a force from the electrode member 35 toward the second recovery member 322 and the first recovery member 321. The negatively charged toner scraped from the second recovery member 322 by the second scraping member 332 flies toward the first recovery member 321 rather than the electrode member 35. As a result, this toner falls directly toward the conveying member 34 without accumulating on the electrode member 35, or adheres to the first recovery member 321, is scraped by the first scraping member 331, and falls toward the conveying member 34. In this way, toner collected from multiple cleaning units can be conveyed by the common conveying member 34 to an outlet provided in the housing 36 without accumulating on the electrode member 35.

[0067] On the other hand, in this embodiment, because the third collection member 323 (or the third cleaning member 313) is negatively charged, an electric field is formed such that negatively charged toner is subjected to a force from the third collection member 323 (or the third cleaning member 313) toward the electrode member 35. When such an electric field is formed, there is a possibility that negatively charged toner will adhere to the electrode member 35. Therefore, in this embodiment, it is desirable that the lower end of the electrode member 35 does not extend below the first collection position N1. Furthermore, the position of the lower end of the electrode member 35 is set so that the electrode member 35 is positioned so that it overlaps at least the first collection member 321 in the vertical direction. Therefore, in this embodiment, the position of the lower end of the electrode member 35 is typically set to a position above the first collection position N1, within a range that overlaps at least the first collection member 321 in the vertical direction.

[0068] As described above, in this embodiment, the first cleaning member 311 and the second cleaning member 312 electrostatically remove toner charged to a predetermined polarity from the surface of the image carrier 20, the third cleaning member 313 electrostatically removes toner charged to a polarity opposite to the predetermined polarity from the surface of the image carrier 20, the transport member 34 transports toner that has fallen from the first recovery section N1, the second recovery section N2, and the third recovery section N3, a voltage of the predetermined polarity is applied to the member (third recovery member) 323 that constitutes the third recovery section N3 and from which toner is recovered in the third recovery section N3, the electrode member 35 is electrically grounded, and the lower end of the electrode member 35 is located above the first recovery section N1.

[0069] The polarity of the toner collected by each cleaning unit may be reversed from that in this embodiment, with the first cleaning unit 301 and the second cleaning unit 302 collecting positive toner and the third cleaning unit collecting negative toner. In this case, the above description can be understood by replacing positive with negative and negative with positive, and reinterpreting the high and low potentials.

[0070] [Example 4] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are assigned the same reference numerals as those of embodiment 1, and detailed descriptions thereof will be omitted.

[0071] In this embodiment, the first cleaning unit 301 collects positive toner, and the second cleaning unit 302 collects negative toner. The third cleaning unit 303 may be provided, or may not be provided as shown in Figure 2. Figure 10 is a schematic diagram for explaining the method of supplying power to the cleaning units in this embodiment.

[0072] The following methods can be used to electrostatically move the positive toner on the intermediate transfer belt 20 to the first cleaning member 311. That is, there is a method in which a negative voltage is applied to the first collection member 321 and the first tension roller 24 is electrically grounded. Note that a negative voltage may be applied directly to the first cleaning member 311 instead of the first collection member 321. Another method is to apply a positive voltage to the first tension roller 24 and electrically ground the first collection member 321. Note that the first cleaning member 311 may be electrically grounded directly instead of the first collection member 321. Either of these methods may be used. Here, a case in which a negative voltage is applied to the first collection member 321 will be taken as an example.

[0073] Similarly, the following method can be used to electrostatically move negative toner on the intermediate transfer belt 20 to the second cleaning member 312. That is, there is a method in which a positive voltage is applied to the second collection member 322 and the second tension roller 25 is electrically grounded. Note that a positive voltage may be applied directly to the second cleaning member 312 instead of the second collection member 322. Another method is to apply a negative voltage to the second tension roller 25 and electrically ground the second collection member 322. Note that the second cleaning member 312 may be electrically grounded directly instead of the second collection member 322. Either of these methods may be used. Here, a case in which a positive voltage is applied to the second collection member 322 will be taken as an example.

[0074] In this embodiment, a negative voltage is applied to the electrode member 35 so that the potential is lower than that of the first recovery member 321. This creates an electric field in which negatively charged toner is subjected to a force from the electrode member 35 toward the second recovery member 322 and the first recovery member 321. The negatively charged toner scraped from the second recovery member 322 by the second scraping member 332 flies toward the first recovery member 321 rather than the electrode member 35. As a result, this toner falls directly toward the conveying member 34 without accumulating on the electrode member 35, or adheres to the first cleaning member 311, is scraped by the first scraping member 331, and falls toward the conveying member 34. In this way, toner collected from multiple cleaning units can be conveyed by the common conveying member 34 to an outlet provided in the housing 36 without accumulating on the electrode member 35.

[0075] In this embodiment, the toner transferred from the first cleaning member 311 to the first collection member 321 has a polarity opposite to that of the toner scraped by the second scraping member 332. Therefore, the toner transferred from the first cleaning member 311 to the first collection member 321 is affected by the electric field, such that the toner is subjected to a force from the first collection member 311 toward the electrode member 35. Therefore, in this embodiment, the position of the lower end of the electrode member 35 is desirably set as follows to ensure that the electric field formed by the electrode member 35 and the first collection member 321 substantially only affects the toner scraped by the second scraping member 332. That is, in this embodiment, it is desirably set so that the lower end of the electrode member 35 does not extend below the first collection position N1. Furthermore, the position of the lower end of the electrode member 35 is set so that the electrode member 35 overlaps at least the first collection member 321 in the vertical direction. Therefore, in this embodiment, the lower end of the electrode member 35 is typically set above the first collection position N1, within a range that overlaps at least the first collection member 321 in the vertical direction.

[0076] As described above, in this embodiment, the first cleaning member 311 electrostatically removes toner charged to a predetermined polarity from the surface of the image carrier 20, the second cleaning member 312 electrostatically removes toner charged to a polarity opposite to the predetermined polarity from the surface of the image carrier 20, a voltage of a polarity opposite to the predetermined polarity is applied to a member (first collection member) 321 constituting the first collection section N1, a voltage of the predetermined polarity is applied to a member (second collection member) 322 constituting the second collection section N2, and a voltage of a polarity opposite to the predetermined polarity is applied to the electrode member 35. Also, in this embodiment, the lower end of the electrode member 35 is located above the first collection section N1.

[0077] The polarity of the toner collected by each cleaning unit may be reversed from that in this embodiment, with negative toner collected by the first cleaning unit 301 and positive toner collected by the second cleaning unit 302. In this case, the above description can be understood by replacing positive polarity with negative polarity and negative polarity with positive polarity, and reinterpreting the high and low potentials. [Explanation of symbols]

[0078] 20 Intermediate transfer belt 24 First tension roller 25 Second tension roller 26 Third tension roller 30 Cleaning device 311, 312, 313 First, second, and third cleaning members 321, 322, 323 First, second, and third recovery members 331, 332, 333 First, second, and third scraping members 34 Conveying member 35 Electrode material 36 Case

Claims

1. A cleaning device for cleaning a surface of a rotatable image carrier on which a toner image is formed at an image forming position, comprising: a first cleaning unit that is disposed along a width direction substantially perpendicular to a direction of movement of the surface of the image carrier, and that includes a first cleaning member that electrostatically removes toner charged to a predetermined polarity from the surface of the image carrier, and a first collection unit that drops and collects the toner removed from the image carrier by the first cleaning member; a second cleaning unit that is disposed along the width direction downstream of the first cleaning unit in the moving direction of the surface of the image carrier and upstream of the image forming position, and that includes a second cleaning unit that electrostatically removes toner from the surface of the image carrier, and a second collection unit that drops and collects the toner removed from the image carrier by the second cleaning unit; a conveying member that conveys the toner that has fallen from the first recovery section and the second recovery section; an electrode member that is disposed along the width direction, and that faces the members that constitute the first recovery portion and the members that constitute the second recovery portion on the opposite side of the image carrier from the members that constitute the first recovery portion and from which toner is recovered in the first recovery portion and the members that constitute the second recovery portion and from which toner is recovered in the second recovery portion; and a cleaning device capable of setting the potential of the electrode member to a potential that generates an electric field in which the toner collected in the second cleaning section moves from the electrode member side to the first collection section side;

2. the first cleaning section includes a first collection member that electrostatically collects toner from the first cleaning member, and a first scraping member that contacts the first collection member to form the first collection section on the first collection member; the second cleaning section includes a second collection member that electrostatically collects toner from the second cleaning member, and a second scraping member that contacts the second collection member to form the second collection section on the second collection member, 2. The cleaning device according to claim 1, wherein the electrode member faces the first and second recovery members on an opposite side of the image carrier with respect to the first and second recovery members.

3. 3. The cleaning device according to claim 2, wherein the length of the electrode member in the width direction is approximately equal to the lengths of the first recovery member and the second recovery member in the width direction.

4. a third cleaning unit that is disposed along the width direction downstream of the image forming position and upstream of the first cleaning member in the moving direction of the surface of the image carrier, and that includes a third cleaning member that electrostatically removes toner from the surface of the image carrier, and a third collection unit that drops and collects the toner removed from the image carrier by the third cleaning member; the second cleaning member electrostatically removes the toner charged to the predetermined polarity from the surface of the image carrier; the third cleaning member electrostatically removes toner charged with a polarity opposite to the predetermined polarity from the surface of the image carrier; the conveying member conveys the toner that has fallen from the first recovery section, the second recovery section, and the third recovery section; 4. The cleaning device according to claim 1, wherein the member constituting the third collection section and from which the toner is collected in the third collection section and the electrode member are electrically grounded.

5. 5. The cleaning device according to claim 4, wherein a lower end of the electrode member is located below the third collection section.

6. a third cleaning unit that is disposed along the width direction downstream of the image forming position and upstream of the first cleaning member in the moving direction of the surface of the image carrier, and that includes a third cleaning member that electrostatically removes toner from the surface of the image carrier, and a third collection unit that drops and collects the toner removed from the image carrier by the third cleaning member; the second cleaning member electrostatically removes the toner charged to the predetermined polarity from the surface of the image carrier; the third cleaning member electrostatically removes toner charged with a polarity opposite to the predetermined polarity from the surface of the image carrier; the conveying member conveys the toner that has fallen from the first recovery section, the second recovery section, and the third recovery section; A voltage of the predetermined polarity is applied to the electrode member, 4. The cleaning device according to claim 1, wherein a lower end of the electrode member is located above the third collection section.

7. 7. The cleaning device according to claim 6, wherein a member constituting the third collection section and collecting the toner in the third collection section is electrically grounded.

8. a third cleaning unit that is disposed along the width direction downstream of the image forming position and upstream of the first cleaning member in the moving direction of the surface of the image carrier, and that includes a third cleaning member that electrostatically removes toner from the surface of the image carrier, and a third collection unit that drops and collects the toner removed from the image carrier by the third cleaning member; the second cleaning member electrostatically removes the toner charged to the predetermined polarity from the surface of the image carrier; the third cleaning member electrostatically removes toner charged with a polarity opposite to the predetermined polarity from the surface of the image carrier; the conveying member conveys the toner that has fallen from the first recovery section, the second recovery section, and the third recovery section; a voltage of the predetermined polarity is applied to a member that configures the third collection section and collects toner in the third collection section; The electrode member is electrically grounded, 4. The cleaning device according to claim 1, wherein a lower end of the electrode member is located above the first collection section.

9. 9. The cleaning device according to claim 4, wherein a voltage of a polarity opposite to the predetermined polarity is applied to a member constituting the first collection section and a member constituting the second collection section.

10. 10. The cleaning device according to claim 4, wherein the third cleaning section comprises a third collection member that electrostatically collects toner from the third cleaning member, and a third scraping member that contacts the third collection member to form the third collection section on the third collection member.

11. 10. The cleaning device according to claim 4, wherein the third cleaning section includes a third scraping member that contacts the third cleaning member to form the third collection section on the third cleaning member.

12. the second cleaning member electrostatically removes toner charged with a polarity opposite to the predetermined polarity from the surface of the image carrier; a voltage of a polarity opposite to the predetermined polarity is applied to a member constituting the first recovery section, A voltage of the predetermined polarity is applied to the members constituting the second recovery section, 4. The cleaning device according to claim 1, wherein a voltage of a polarity opposite to the predetermined polarity is applied to the electrode member.

13. 13. The cleaning device according to claim 1, wherein a lower end of the electrode member is located above the first collection section.

14. 14. The cleaning device according to claim 1, wherein the electrode member forms a part of a housing of the cleaning device.

15. an image carrier; an image forming unit that forms a toner image on the image carrier at an image forming position; A cleaning device according to any one of claims 1 to 14; An image forming apparatus comprising:

Images