JP2007304217A - Cleaning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device of an image forming apparatus for improving durability by supplying a sufficient magnetic developer on a cleaning blade at a low cost without causing large size of the device and complicatedness of a device structure. <P>SOLUTION: The cleaning device 20 is incorporated in the image forming apparatus 1 using at least one kind of the magnetic developer for image formation. In addition, the cleaning device 20 is provided with a cleaning blade 22 for scratching off the developer remaining on an endless belt 2 by being contacted on a part wound on a suspension roller 23 of the endless belt 2 suspended on the suspension roller 23. The suspension roller 23 is a magnet roller arranging magnetic poles different in polarity in a circumferential direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cleaning device for an image forming apparatus using an electrophotographic process such as an electrostatic copying machine or a printer.

  As a conventional image forming apparatus of this type, a toner image formed on an image carrier that is a photosensitive member is transferred to an endless belt-shaped intermediate transfer belt suspended by a plurality of suspension rollers, and the toner on the intermediate transfer belt Some transfer images to sheets. A cleaning device is disposed on the downstream side of the sheet transfer position of the intermediate transfer belt, and the cleaning device has a cleaning blade that comes into contact with a portion of the intermediate transfer belt wound around a suspension roller. Then, when the intermediate transfer belt is driven, the edge portion (contact portion) of the cleaning blade is brought into sliding contact with the intermediate transfer belt, whereby the toner remaining on the intermediate transfer belt is scraped off and cleaned.

  Incidentally, the cleaning blade is generally formed of an elastic material such as rubber in order to bring the edge portion into uniform contact with the intermediate transfer belt. Therefore, the edge portion which is the belt sliding contact portion of the cleaning blade is easily worn out due to wear, and is inferior in durability. Therefore, in the case of an image forming apparatus using a magnetic developer for image formation, an apparatus in which a magnet roller is disposed on the upstream side of an intermediate transfer belt of a cleaning blade has been proposed (see Patent Document 1). The magnetic force of the magnet roller attracts and supplies toner (magnetic developer) as a lubricant to the edge portion of the cleaning blade to suppress wear of the edge portion, thereby improving durability.

  In addition, in order to reduce the sliding load of the cleaning blade and suppress the wear of the edge portion, toner is also supplied to the edge portion separately from the image forming.

  Further, there is an image forming apparatus that uses a transfer conveyance belt instead of an intermediate transfer belt and directly transfers a toner image from an image forming unit onto a sheet conveyed by the transfer conveyance belt (see Patent Document 2). As in the case of the intermediate transfer belt, a cleaning device is disposed on the downstream side of the sheet transfer position of the transfer conveyance belt. The edge portion of the cleaning blade that comes into contact with the portion of the transfer / conveying belt wound around the suspension roller is brought into sliding contact with the belt when the belt is driven, so that the toner remaining on the belt is scraped off and cleaned.

  In the case of the image forming apparatus using the transfer / conveying belt, the toner image is directly transferred onto the sheet, so the amount of toner remaining on the belt is very small. It is difficult to sufficiently supply toner as a lubricant. Therefore, similarly to the above, toner is supplied to the edge portion of the cleaning blade separately from the image forming portion to reduce the sliding load on the edge portion.

Japanese Patent Laid-Open No. 2004-347795 JP 2004-334242 A

  However, if the magnet roller is arranged on the upstream side of the belt of the cleaning blade of the cleaning device as in Patent Document 1, the number of parts increases and the size of the device increases. In addition, since a separate magnet roller driving device is required, the structure of the device becomes complicated and the cost is hindered.

  Further, in the image forming apparatus using the intermediate transfer belt or the transfer conveyance belt, if toner is supplied to the edge portion of the cleaning blade separately from the image forming, the supplied toner is consumed as it is not used for image formation. As a result, the toner consumption increases and the cost increases.

  Therefore, the present invention makes it possible to supply a sufficient magnetic developer to the cleaning blade at a low cost without increasing the size of the apparatus or complicating the structure of the apparatus, thereby improving durability. It is an object to provide a cleaning device and an image forming apparatus.

In order to achieve the above object, the present invention includes an image forming apparatus that uses at least one magnetic developer for image formation and that is wound around a suspension roller of an endless belt that is suspended by a suspension roller. A cleaning device comprising a cleaning blade that contacts and scrapes off the developer remaining on the endless belt,
The suspension roller is a magnet roller.

Further, the present invention comprises a cleaning device having a cleaning blade that contacts a portion of the endless belt that is suspended by the suspension roller and wound around the suspension roller, and scrapes off the developer remaining on the endless belt, An image forming apparatus that forms an image on the surface of a sheet using at least one magnetic developer for image formation,
The suspension roller is a magnet roller.

  According to the present invention, the suspension roller that suspends the endless belt at the contact position of the cleaning blade with the endless belt is the magnet roller. Accordingly, when the endless belt is driven, the magnet roller rotates as the belt advances, and the magnetic force moves in the belt moving direction, and the magnetic developer is attracted by the magnetic force and supplied to the edge portion of the cleaning blade. This reduces the sliding load on the edge portion of the cleaning blade, suppresses wear of the edge portion, and improves the durability of the cleaning device.

  In addition, since the suspension roller around which the endless belt is wound is a magnet roller, the number of parts is not increased, and there is no need to newly provide a magnet roller driving device. Thus, the magnetic developer can be sufficiently supplied to the cleaning blade at a low cost without causing an increase in the size of the cleaning device and a complicated structure of the device.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  First, an image forming apparatus incorporating an intermediate transfer belt cleaning device as an example of an embodiment of the present invention and a toner as a magnetic developer used for image formation will be described.

  The image forming apparatus 1 shown in FIG. 1 uses an intermediate transfer belt 2, and a paper feed cassette 3 on which a plurality of sheets are stacked is horizontally arranged at the bottom. The sheet taken out from the paper feed cassette 3 is conveyed to the second transfer member 5 through the registration roller 4. Above the intermediate transfer belt 2, four image forming portions Pa, Pb, Pc, Pd are arranged in series. Since the image forming portions Pa, Pb, Pc, and Pd have the same structure except that each forms a toner image of each color of magenta, cyan, yellow, and black, the image forming portion Pa will be described.

  The image forming portion Pa includes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 6 that is rotatably arranged. Around the photosensitive drum 6, process devices such as a primary charger 7 and a developing device 8 are arranged. The developing devices 8 of the image forming units Pa, Pb, Pc, and Pd store magenta toner, cyan toner, yellow toner, and black toner, respectively.

  An image signal based on the magenta component color of the original is projected onto the photosensitive drum 6 via a polygon mirror (not shown) or the like to form an electrostatic latent image. Magenta toner is applied to the electrostatic image from the developing unit 8. The supplied electrostatic latent image becomes a magenta toner image. When this toner image reaches the toner image transfer position where the photosensitive drum 6 and the intermediate transfer belt 2 come into contact with the rotation of the photosensitive drum 6, the magenta toner image is transferred by the transfer bias applied by the first transfer member 9. Transferred to the intermediate transfer belt 2.

  Similarly, as the intermediate transfer belt 2 carrying the magenta toner image advances to the image forming portions Pb, Pc, and Pd, the cyan toner image, the yellow toner image, and the black toner are similarly processed at the respective toner image transfer positions. Images are sequentially superimposed and transferred.

  Here, as a toner developing method of the electrostatic latent image, for the three color toners other than the black toner, a two-component contact developing method using a mixture of toner particles and a magnetic carrier as a developer is used. For black toner, the one-component contact development method using magnetic toner is used.

  The four color toner images transferred to the intermediate transfer belt 2 are transferred at a sheet transfer position below the intermediate transfer belt 2 by a transfer bias applied by the second transfer member 5 to the sheet that has reached the sheet transfer position. Is done. The sheet onto which the four color toner images have been transferred is conveyed to the fixing device 10, where the toner image is thermally fixed by heat and pressure, and the sheet on which the toner image has been fixed is discharged to the paper discharge tray 11. Also, an intermediate transfer belt cleaning device 20 that scrapes and cleans toner remaining on the intermediate transfer belt 2 is disposed downstream of the sheet transfer position of the intermediate transfer belt 2.

The intermediate transfer belt 2 employs a polyimide resin in which carbon as an electronic conductive material is dispersed, and has a surface resistivity of 10 ¹⁰ to 10 ¹³ Ω / □ and a volume resistivity of 10 ⁹ to 10 ¹¹ Ω · cm. It is said. The polyimide resin is a very strong resin and is optimal for extending the life of the intermediate transfer belt 2, but is not limited thereto. For example, a dielectric resin such as a polyethylene terephthalate resin film and a polyvinylidene fluoride resin film, or an organic compound having rubber elasticity such as urethane or chloroprene may be employed. Further, a composite of these resins and a material having rubber elasticity may be used.

  In this embodiment, a cleaningless system that does not have a step of cleaning the transfer residual toner on the photosensitive drum 6 is employed. That is, the transfer residual toner on the photosensitive drum 6 is removed from the photosensitive drum 6 by “development simultaneous cleaning” by the developing device 8 and collected and reused in the developing device 8.

  Simultaneous development cleaning refers to a fog removal bias (fogging potential difference Vback which is a potential difference between a DC voltage applied to the developing device and the surface potential of the photosensitive drum) when toner slightly remaining on the photosensitive drum 6 after transfer is developed in the subsequent process. ). According to this method, since the transfer residual toner is collected by the developing device 8 and used in the subsequent steps, waste toner can be eliminated, and troublesome maintenance can be reduced. Further, since the cleaner is not required, an advantage in terms of space is great, and the image forming apparatus can be greatly downsized.

  As a technology that supports this cleaningless system, there is a polymerized toner technology. In general, a toner produced by a polymerization method has a very high sphericity, and it is relatively easy to maintain a transfer efficiency of 98% or more. Further, by adopting the intermediate transfer method, it is possible to maintain high transfer efficiency relatively stably under any conditions. Therefore, it is possible to omit the cleaning device for the photosensitive drum 6 and collect the remaining transfer residual toner in the developing device 8.

  Further, by mixing the wax component when the toner is polymerized, it is not necessary to apply oil to the fixing portion, and the fixing device 10 can be downsized and the running cost can be reduced.

  Further, many proposals have been made regarding surface modification for improving the dispersibility of the magnetic substance in the polymerized toner. For example, various silane coupling agent treatment techniques for magnetic materials are disclosed in Japanese Patent Application Laid-Open Nos. 59-200254, 59-2000025, 59-200277, and 59-224102. Proposed. Japanese Patent Application Laid-Open No. 63-250660 and Japanese Patent Application Laid-Open No. 10-239897 disclose techniques for treating silicon element-containing magnetic particles with a silane coupling agent.

  If both magnetic and non-magnetic toners have poor sphericity, the amount of residual toner is increased, making it difficult to employ a cleaningless system. According to the study by the present inventors, the value of the shape factor SF-1 measured by the image analysis apparatus with respect to the sphericity is 100 ≦ SF-1 ≦ 160, and the value of SF-2 is 100 ≦ SF-2 ≦ 140. It turned out to be preferable. SF-1 and SF-2 indicating the shape factor are defined as follows.

  For example, using a FE-SEM (S-800) manufactured by Hitachi, Ltd., 100 toner images of 2 μm or larger magnified 1000 times are sampled randomly, and the image information is, for example, an image analyzer manufactured by Nireco Corporation ( (Luxex III (trade name)) for input and analysis. And the value obtained by calculating by the following formula based on the analysis result is defined as shape factors SF-1 and SF-2.

SF-1 = (MXLNG) 2 / (AREA) × (π / 4) × 100
SF-2 = (PERIME) 2 / (AREA) × (1 / 4π) × 100
Where MXLNG is the absolute maximum length of the particle, PERIME is the perimeter of the particle, and AREA is the projected area of the particle.

  The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape factor SF-2 indicates the degree of unevenness of the toner particles. The closer to 100, the closer to a true sphere. When the toner SF-1 exceeds 160, the toner moves away from the spherical shape and approaches an indeterminate shape, so that the toner is easily crushed in the developing device 8, the particle size distribution is fluctuated, the charge amount distribution is likely to be broad, Reversal fog is likely to occur.

  A toner having a high sphericity can be produced by a method of obtaining a spherical toner by atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in JP-B-56-13945. Further, it can be produced by a method for directly producing toner using the suspension polymerization method described in JP-A-59-53856 and JP-A-59-61842. Furthermore, a dispersion polymerization method in which a toner is directly produced using a water-based organic solvent in which the monomer is soluble and the resulting polymer is insoluble, or a soap is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator. It can be produced by an emulsion polymerization method typified by a free polymerization method.

  Among these, the method of directly producing toner using the suspension polymerization method described in JP-A-59-53856 and JP-A-59-61842 is particularly preferable. In addition, a seed polymerization method in which a monomer is further adsorbed to the obtained polymer particles and then polymerized using a polymerization initiator can also be suitably used. Furthermore, it is preferable to add polar resins such as a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, and a saturated polyester resin. Further, when the direct polymerization method is used, it is preferable to add a charge control agent which has no polymerization inhibition and does not have a solubilized product in an aqueous system.

  As a specific example of a method for producing a toner using a direct polymerization method, first, a release agent, a colorant, a charge control agent, a polymerization initiator and other additives composed of a low softening substance are added to a monomer. . Next, the monomer system uniformly dissolved or dispersed by a homogenizer / ultrasonic disperser or the like is dispersed in an aqueous phase containing a dispersion stabilizer by an ordinary stirrer, homomixer, homogenizer or the like. In this case, the granulation is preferably performed by adjusting the stirring speed and time so that the monomer droplets have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. The polymerization is carried out at a temperature of 40 ° C. or higher, generally 50 to 90 ° C.

  In this embodiment, since a cleaningless system is employed in the image forming unit, it is advantageous to use a spherical toner by a polymerization method or the like. However, when a cleaning device for the photosensitive drum 6 is provided in the image forming unit, An irregularly shaped toner obtained by a conventional pulverization method may be used.

  Next, an intermediate transfer belt cleaning device, which is an example of an embodiment of the present invention, will be described with reference to FIGS.

  As shown in FIG. 2, the intermediate transfer belt cleaning device 20, which is an example of an embodiment of the present invention, is attached to the cleaning container 21 and the cleaning container 21 and scrapes off residual toner on the intermediate transfer belt 2. And a blade 22.

  As shown in FIG. 1, the cleaning container 21 faces the portion of the intermediate transfer belt 2 that is suspended by the suspension roller 23 on the downstream side of the sheet transfer position of the second transfer member 5 and is wound around the suspension roller 23. Are arranged. The cleaning container 21 extends along the width direction of the intermediate transfer belt 2 (the axial direction of the suspension roller 23), and an opening 24 facing the portion of the intermediate transfer belt 2 wound around the suspension roller 23 is provided on the suspension roller 23. Open along the axial direction. Conveying means (not shown) for discharging residual toner is disposed inside the cleaning container 21. The conveying means conveys the residual toner dropped into the cleaning container 21 along the axial direction of the suspension roller 23 and discharges it from the cleaning container 21.

  The cleaning blade 22 is attached along the axial direction of the suspension roller 23 via a support member 25 above the opening 24 of the cleaning container 21. In such an attached state, the cleaning blade 22 is arranged with the width direction oriented substantially in the same direction as the direction in which the intermediate transfer belt 2 enters the suspension roller 23, and the leading end of the cleaning blade 22 serves as an edge portion. Is in contact with a portion wound around the suspension roller 23. When the intermediate transfer belt 2 is driven, if the toner that cannot be transferred by the second transfer member 5 and remains on the intermediate transfer belt 2 reaches the edge of the cleaning blade 22, the residual toner is scraped off by the edge. It is. A scooping sheet 26 is attached below the opening 24 of the cleaning container 21. The scooping sheet 26 causes the residual toner scraped off by the edge portion of the cleaning blade 22 to fall into the cleaning container 21 and prevents the residual toner that has fallen from flowing back to the intermediate transfer belt 2 in a large amount.

  Here, the cleaning blade 22 is attached to the support member 25 so that the pressing force per unit length against the intermediate transfer belt 2 is, for example, 500 mN / cm. The material of the cleaning blade 22 is, for example, polyurethane rubber, and its physical property values are actually measured values according to the JIS vulcanized rubber test method, and the A hardness is 73 ° and the rebound resilience is 50%.

  A suspension roller 23 that suspends the intermediate transfer belt 2 at a position where the cleaning blade 22 contacts the intermediate transfer belt 2 is a magnet roller as shown in FIG. In this embodiment, the magnet roller 23 has, for example, a total of eight magnetic poles of four N poles and four S poles arranged in the circumferential direction, and the magnetic flux density is 50 mT.

  When the intermediate transfer belt 2 is driven and the magnet roller 23 rotates as the belt travels, the magnetic force of the magnet roller 23 moves in the belt traveling direction. The residual toner staying in the cleaning container 21 by the moving magnetic force is attracted to the intermediate transfer belt 2 and is transported together with the intermediate transfer belt 2, and magnetic toner as a lubricant is always supplied to the edge portion of the cleaning blade 22.

  Thus, in this embodiment, the magnetic toner as the lubricant can be always supplied to the edge portion of the cleaning blade 22 when the intermediate transfer belt 2 is driven. Thereby, the sliding load of the edge part of the cleaning blade 22 is reduced, the wear of the edge part is suppressed, and the durability of the cleaning device 20 can be improved.

  Further, since the suspension roller 23 around which the intermediate transfer belt 2 is wound is a magnet roller, the number of parts is not increased, and a magnet roller driving device is not required to be newly installed. Accordingly, the magnetic toner as the lubricant can be sufficiently supplied to the cleaning blade 22 at a low cost without causing an increase in the size of the cleaning device 20 and a complicated structure of the device.

  Furthermore, since the durability of the cleaning device 20 can be improved simply by using the suspension roller 23 around which the intermediate transfer belt 2 is wound as a magnet roller, the effect of improving the durability can be easily obtained. In this case, the suspension roller 23 may be a magnet roller when the image forming apparatus is manufactured, or the existing suspension roller may be replaced with a magnet roller after the image forming apparatus is manufactured.

  Next, as an image forming apparatus with a built-in intermediate transfer belt cleaning device, a copier “trade name: iRC3200 (manufactured by Canon Inc.)” was used, and the durability test of the cleaning blade was performed on the present invention example and the comparative example. went. Here, the example of the present invention is the cleaning device 20 having the same configuration as that of FIG. 2, and the comparative example is that the suspension roller 23 of the cleaning device 20 of FIG. 2 is a normal suspension roller. The other conditions were the same for both the inventive example and the comparative example.

  In the example of the present invention, even when 100,000 solid white images were formed, the toner on the edge portion of the cleaning blade 22 was not depleted and could be normally cleaned. On the other hand, in the comparative example, when about 10,000 solid white images are formed, the toner near the edge of the cleaning blade 22 is depleted, the sliding load of the edge increases, and the frictional force increases. There was a problem that the cleaning blade 22 turned over.

  Next, referring to FIG. 3, an intermediate transfer belt cleaning device according to another embodiment of the present invention will be described. Note that portions overlapping with the above embodiment are described with the same reference numerals.

  In the other embodiment of the present invention, the intermediate transfer belt cleaning device 20A uses the suspension roller 23 as a magnet roller as in the above embodiment, but the magnetic pole arrangement of the magnet roller is changed. . That is, as shown in FIG. 3, the magnet roller 23 has a total of eight magnetic poles arranged in two sets of N poles, N poles, S poles, and S poles in the circumferential direction. A circumferential region of a magnetic pole having a repulsive polarity (a magnetic pole having no magnetic binding force) is large. The magnetic flux density is set to 50 mT as in the above embodiment.

  In this way, when the intermediate transfer belt 2 to which a large amount of magnetic toner adheres due to a paper jam or the like reaches the cleaning blade 22, the magnetic toner can be more easily peeled off from the cleaning blade 22 than in the above embodiment. it can. That is, since the area in the circumferential direction of the magnetic pole having a repulsive polarity with respect to the magnetic toner of the magnet roller 23 is large, the magnetic toner can be easily detached from the cleaning blade 22 by reaching the cleaning blade 22. Can do.

  On the other hand, an appropriate amount of magnetic toner is attracted from the cleaning container 21 to the intermediate transfer belt 2 by the magnetic pole having a magnetic binding force with respect to the magnetic toner of the magnet roller 23, and is conveyed together with the intermediate transfer belt 2.

  As a result, even when a large amount of residual toner adheres to the intermediate transfer belt 2 due to a paper jam or the like, the magnetic toner as the lubricant is properly applied to the cleaning blade 22 without depositing the magnetic toner on the edge portion of the cleaning blade 22. Quantity can be supplied.

  The magnetic developer, the image forming unit, the suspension roller, the endless belt, the cleaning blade, the cleaning container, the magnet roller, and the like of the present invention are not limited to those exemplified in the above embodiment, but the gist of the present invention. Changes can be made as appropriate without departing from the scope.

  For example, in the above embodiment, the intermediate transfer belt cleaning device built in the intermediate transfer belt type image forming apparatus is exemplified, but instead, the transfer conveyance built in the transfer conveyance belt type image forming apparatus. The present invention may be applied to a belt cleaning device.

  FIG. 4 shows an outline of a general transfer conveyance belt type image forming apparatus 1A. Note that portions that overlap or correspond to the intermediate transfer belt type image forming apparatus already described with reference to FIG.

  In the transfer conveyance belt type image forming apparatus 1 </ b> A, a sheet taken out from the paper feed cassette 3 is supplied onto the transfer conveyance belt 30 via the registration roller 3. After the supply, the sheet conveyed on the transfer conveyance belt 30 by the transfer bias applied by the first transfer member 9 at the toner image transfer position (= sheet transfer position) of each image forming portion Pa, Pb, Pc, Pd. The toner image is directly transferred to the toner image.

  Then, the cleaning device 20 having the same configuration as that of FIG. 2 is opposed to the portion of the transfer conveyance belt 30 that is suspended by the suspension roller 23 on the downstream side of the toner image transfer position of the image forming unit Pd and wound around the suspension roller 23. Are arranged. Since the belt traveling direction of the transfer conveyance belt 30 is opposite to that of the intermediate transfer belt 2 shown in FIG. 1, in FIG. 4, the cleaning device 20 is installed in a different direction from FIG.

  In the image forming apparatus using the transfer / conveyance belt 30, toner is not positively supplied onto the transfer / conveyance belt 30 during image formation. For this reason, the amount of toner remaining on the transfer / conveying belt 30 is very small. For example, once the magnetic toner is supplied to the cleaning container 21, the magnetic toner is always supplied to the cleaning blade 22 when the belt is driven. . Therefore, good slidability of the cleaning blade 22 can be maintained over a long period of time.

FIG. 3 is an explanatory diagram for explaining an image forming apparatus including a cleaning device for an intermediate transfer belt, which is an example of an embodiment of the present invention. FIG. 3 is a cross-sectional view for explaining an intermediate transfer belt cleaning device as an example of an embodiment of the present invention. It is sectional drawing for demonstrating the cleaning apparatus for intermediate transfer belts which is other embodiment of this invention. It is an explanatory diagram for explaining an example of an image forming apparatus using a transfer conveyance belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Intermediate transfer belt Pa, Pb, Pc, Pd Image forming part 20 Cleaning device 22 Cleaning blade 23 Magnet roller (suspension roller)
30 Transfer conveyor belt

Claims (5)

The development remaining in the endless belt in contact with a portion of the endless belt wound around the suspension roller that is built in the image forming apparatus that uses at least one magnetic developer for image formation and is wound around the suspension roller. A cleaning device having a cleaning blade for scraping off the agent,
A cleaning device, wherein the suspension roller is a magnet roller.   The cleaning device according to claim 1, wherein magnetic poles having different polarities are arranged in the circumferential direction of the magnet roller. At least one type of magnetic development comprising a cleaning device that has a cleaning blade that abuts on a portion of the endless belt that is suspended by the suspension roller and that is wound around the suspension roller and scrapes off the developer remaining on the endless belt. An image forming apparatus that forms an image on the surface of a sheet using an agent for image formation,
An image forming apparatus, wherein the suspension roller is a magnet roller.   The image forming apparatus according to claim 3, wherein magnetic poles having different polarities are arranged in the circumferential direction of the magnet roller. The image forming apparatus according to claim 3, wherein the endless belt is an intermediate transfer belt or a transfer conveyance belt.

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