Abstract: An image forming apparatus includes an image forming unit; an intermediate transfer member; a secondary transfer member to form a secondary transfer nip with the intermediate transfer member and the secondary transfer member; a biasing mechanism to bias the secondary transfer member toward the intermediate transfer member; a cam member rotatable between a first position, at which a predetermined space is formed in the secondary transfer nip, and a second position, at which the secondary transfer member and the intermediate transfer member contact each other; and a contact-separation controller configured to put the cam member in the first position before entry of the recording medium into the secondary transfer nip, rotate the cam member toward the second position when the recording medium enters the secondary transfer nip, and change a start timing of rotation of the cam member in accordance with a thickness of the recording medium.

Abstract: An endless belt member for an image forming apparatus includes an endless belt member body that contains a resin and conductive particles, an inner transparent film, a position detection member that is used to detect the position of the endless belt member body, and an outer transparent film, wherein the position detection member is sealed by the inner and outer transparent films, is provided on a part of an outer peripheral surface of the endless belt member body, and has side surfaces which are substantially perpendicular to the outer peripheral surface of the endless belt member body, and the inner and outer transparent films are welded to each other at portions, which is adjoining the side surfaces of the position detection member, of the portions that come into direct contact with each other.

Abstract: An intermediate transfer belt having a circumferential length not less than 2,000 mm and is driven at a linear speed not less than 350 mm/sec and an inner circumferential surface having a surface roughness Ra of from 0.2 to 0.4 ?m (JIS B0601: '01), and including a substrate layer and a high-resistivity layer having a resistivity higher than that of the substrate layer, wherein the high-resistivity layer has a surface resistivity higher than that of the substrate layer by 0.3 to 2.5 log ?/? in common logarithm value when applied with a voltage of 500 V.

Abstract: A cast-in reflective timing patch for a belt such as an intermediate transfer belt of a printing device. The timing patch is formed during manufacturing of the belt. As such, the presence, quality, location, and alignment of the timing patch is fixed and inspection and monitoring of the timing patch is no longer required.

Abstract: An intermediate transfer device including an intermediate transfer body having a primary transfer portion and a secondary transfer portion which bears a secondary image formed by transferring a primary image from an image bearing member; a pair of secondary transfer rollers having a secondary transfer roller and a support roller provided in contact with each other via the intermediate transfer body at the secondary transfer portion, which transfers the secondary image to a recording medium at the secondary transfer portion; a variation detection device that detects an amount of variance occurring to a transfer rotation body when the recording medium is transferred to the secondary transfer portion; and an adjustment device that adjusts the distance between the pair of the secondary transfer rollers according to the amount of variance detected by the variation detection device.

Abstract: An image forming apparatus includes: an image carrier; an intermediate transfer unit including an intermediate transfer body onto which an image on the image carrier is transferred, and plural rotation members around which the intermediate transfer body is wound, each rotation member rotating around a rotation axis, the intermediate transfer unit detachably attached, in the rotation axis direction, to an apparatus main body; a secondary transfer unit that makes contact with and separates from the intermediate transfer body, the secondary transfer unit provided at an opposite side of the rotation members across the intermediate transfer body; a positioning unit that, when the intermediate transfer unit is attached to the apparatus main body, positions the intermediate transfer unit in the secondary transfer unit side at least at two points differently located in the rotation axis direction; and a securing unit that secures the intermediate transfer unit to the apparatus main body.

Abstract: An image forming apparatus includes toner image forming units that are arranged in a line at two end portions and at an intermediate portion of the line, each of the toner image forming units forming a toner image; an image transfer body to which the toner images formed by the toner image forming units are transferred; pressing members that are linearly arranged so that each of the pressing members faces a corresponding one of the toner image forming units with the image transfer body therebetween, each of the pressing members applying a pressing force to the image transfer body; and a fixing unit that fixes the toner images on a recording member. The pressing forces applied by the pressing members that are disposed at the two end portions are smaller than the pressing force applied by the pressing member that is disposed in the intermediate portion.

Abstract: A detection apparatus includes the following elements. A first measuring unit measures, from a binary image, density levels of first and second regions which are alternately arranged in a first direction in the binary image, the binary image being disposed on a second surface of a holding member which includes a first surface and the second surface. A storage unit stores therein information indicating an association between a distance from the first measuring unit to the second surface and a contrast between the adjacent first and second regions. A calculator calculates a contrast between the adjacent first and second regions. A detector specifies a distance corresponding to the calculated contrast by using the stored information, and detects a deflection of the holding member in the first direction by using the specified distance as the distance from the second surface to the adjacent first and second regions.

Abstract: A disclosed to-be-transferred object length measurement device includes a first rotating body; a passage detection unit detecting a passage of the to-be-transferred object; a rotation amount measurement unit measuring a rotation amount of the first rotating body in a first measurement period; a second rotating body feeding the to-be-transferred object; a speed detection unit detecting a first feeding speed and a second feeding speed of the to-be-transferred object; and a calculation unit calculating a feeding distance of the to-be-transferred object per a predetermined rotation amount of the first rotating body based on the first feeding speed, and further calculating a length of the to-be-transferred object based on the rotation amount of the first rotating body in the first measurement period, the feeding distance, and the second feeding speed of the to-be-transferred object in the second measurement period.

Abstract: It has been difficult to ensure satisfactory secondary transfer performance while ensuring satisfactory primary transfer performance by passing a current in the circumferential direction of an intermediate transfer belt from a current supply member. To satisfy a relationship of Rv>Rs, where Rv is resistance in the thickness direction of an intermediate transfer belt and Rs is resistance in the circumferential direction of the intermediate transfer belt over the distance between an image carrier located most upstream and an image carrier located most downstream in the movement direction of the intermediate transfer belt.

Abstract: A cam driving mechanism has: a cam; a motor which drives the cam; a gear train which transmits, while reducing the speed of, the output of the motor to the cam; a pulse disk which is formed integrally with a gear coupled in the gear train and in which a plurality of slits are formed at equal intervals; a home position detecting member which is arranged coaxially with the pulse disk so as to be rotatable independently thereof and which, by meshing with another gear coupled in the gear train, rotates at a lower rotation speed than the pulse disk; and a cam position detecting sensor which has a detecting portion including a light-emitting portion and a light-receiving portion, the cam position detecting sensor detecting the amount of driving of the cam based on the number of slits of the pulse disk that have passed through the detecting portion, the cam position detecting sensor detecting the home position of the cam based on the timing with which the home position detecting member shields the detecting portion.

Abstract: An image forming apparatus has a rotatable belt, a stretching unit for stretching the belt, a steering unit for stretching and steering the belt, wherein the steering unit includes a rotatable portion rotatable with rotation of the belt, a frictional portion, provided at each of opposite axial end of the rotation portion, for slidable contact with the belt, and a support for the rotatable portion and the frictional portion. A rotation shaft rotatably supports the support, and the steering unit is capable of steering the belt by rotation thereof from sliding between the belt and the frictional portion, wherein each of the frictional portions is provided with an inclined surface which is inclined to be further from a rotational axis of the rotation portion axially toward an outside, and wherein the belt is contacted to at least one of the inclined portions.

Abstract: A method and electrostatographic printer for forming a multi-color image on a web-fed receptor material. The method includes receiving a toner image on a first toner image-collecting device in a first color unit; transferring the toner image images on the first image-collecting device at a single transfer point to the final toner image-collecting device in a final colour unit; and transferring the toner image or images collected on the final toner-image collecting device in the array of at least two image-collecting devices directly or indirectly to the receptor material at a single transfer point at one side of the receptor element using a transfer device such that the collected toner image transferred from the final toner image-collecting device using the transfer device contain the individual images from all image-forming stations in the multiple colour units, wherein at least one of the image-collecting devices is a seamless belt.

Abstract: The movement detection apparatus acquires a movement state of an object by clipping a template pattern from first image data and seeking a region having a high correlation with the template pattern in second image data. The movement detection apparatus performs at least one of first processing, which analyzes the first image data, and second processing, which analyzes a relationship between the first image data and third image data acquired after the first image data has been acquired and before the second image data is acquired, and sets a position at which the template patter is clipped.

Abstract: The present disclosure provides for an intermediate transfer member for receiving an ink image from a first surface and transferring it to a second surface, comprising: a base; a rubber layer disposed on the base; a primer disposed on the rubber layer and comprising an aminofunctional organic compound, a photoinitiator, and a catalyst; and a release layer disposed on the primer, wherein the release layer comprises a silicone polymer capable of being cured by the catalyst.

Abstract: An image forming apparatus comprising an image carrying member for carrying a toner image; a intermediary member for carrying the toner image transferred from said image carrying member; a first transfer member for transferring the toner image from said intermediary member onto a sheet, said first transfer member having first resistance and being contacted to said intermediary member; a second transfer member for transferring the toner image from said intermediary member onto the sheet, said second transfer member having second resistance higher than the first resistance and being contacted to said intermediary member at a position downstream of said first transfer member; and voltage applying means, connected to both of said first transfer member and said second transfer member, for applying the same voltage to said first transfer member and to said second transfer member to transfer the toner image onto the sheet.

Abstract: An image forming apparatus can form a high-quality image without a toner image being rubbed with and transferred onto a sheet.

Abstract: A roller device includes a cylinder member. The cylinder member includes wall member having a plurality of channels that are disposed within the wall member. The channels circulate a fluid therein to uniformly regulate a temperature of the cylinder member.

Abstract: A seamless belt formed of a polyimide including a repeating unit represented by the formula (1): in which 25 mol % to 95 mol % of A is a tetravalent unit represented by the formula (2): 75 mol % to 5 mol % of A is a tetravalent unit represented by the formula (3): 15 mol % to 95 mol % of B is a divalent unit represented by the formula (4): and 85 mol % to 5 mol % of B is a divalent unit represented by the formula (5):

Abstract: An image forming apparatus to form an image in a single pass includes a plurality of image carriers, a transfer belt to receive developer images from the image carriers, a plurality of primary transfer rollers disposed to be offset from the image carriers along the transfer belt, respectively, a backup roller disposed adjacent to the last one of the primary transfer rollers disposed most-downstream in a rotating direction of the transfer belt, and a secondary transfer roller to transfer the developer images from the transfer belt to a printing medium, the secondary transfer roller being disposed opposite to the backup roller to interpose the transfer belt therebetween. The backup roller has a resistance in the range of 5 to 50 M?.

Abstract: A toner pattern for detecting the degree of toner deterioration is created on a photosensitive element and transferred to an intermediate transfer belt by a primary transfer unit under a transfer condition different from that at the time of image formation. A toner adhesion amount detection unit detects the toner adhesion amount of the toner pattern at multiple places. A degree-of-toner-deterioration calculation unit calculates the degree of toner deterioration on the basis of the variation in data of the toner adhesion amount at multiple places detected by the toner adhesion amount detection unit. A background potential determination coefficient in a process control unit is controlled on the basis of the degree of toner deterioration calculated by the degree-of-toner-deterioration calculation unit.

Abstract: An image forming apparatus includes a rotatable belt member; an image forming station; first and second detecting members for detecting widthwise positions of the belt member; first and second steering rollers for correcting the widthwise positions of the belt member by inclination; a control portion configured to control inclinations of the first and second steering rollers on the basis of an output of the first or second detecting member; a first executing portion configured to execute, in a period other than an image formation period, an operation in a correction mode of, in a state that the first steering roller is at a first reference inclination, controlling the second steering roller to correct a second reference inclination of the second steering roller; and a second executing portion configured to execute, in a period other than that of the correction mode operation, an operation in a control mode of controlling the first and second steering rollers on the basis of the first and second reference incl

Abstract: An image forming apparatus including a main assembly; an intermediary transfer unit including an endless intermediary transfer belt, a plurality of rollers including a driving roller for applying a driving force to the intermediary transfer belt and stretching the intermediary transfer belt, and an intermediary transfer frame integrally supporting the rollers; a main assembly rail member, fixed to the main assembly, for guiding the intermediary transfer unit, the main assembly rail member regulating and positioning at least the driving roller and a roller around which the intermediary transfer belt is wound with a wrapping angle not less than 90° in a state that intermediary transfer unit is mounted in the main assembly.

Abstract: An image forming apparatus includes: a transfer belt that is stretched on a plurality of support rollers including a backup roller in a loop-like manner and has an outer surface for carrying thereon a toner image; a transfer roller that is brought into pressurized contact with the backup roller across the transfer belt and forms a transfer nip with the transfer belt; a restriction member that is placed upstream of a transfer nip in a sheet conveying direction so as to be switchable between a first state in which the restriction member is brought closer to an inner surface of the transfer belt and a second state in which a distance of the restriction member from the inner surface of the transfer belt is larger than that in the first state; and a control section that switches a state of the restriction member.

Abstract: An intermediate transfer member (34) (ITM) transfers a toner image from an image bearing surface to a substrate. The ITM has an outermost surface having a roughness of less than or equal to about 300 Angstroms root-mean-square (RMS). An imaging liquid developer system (22) sequentially deposits differently colored layers of pigment containing material onto the outermost surface, wherein at least one of the layers has a final film thickness of less than or equal to 1 ?m at 100 percent coverage.

Abstract: An image forming apparatus includes a movable belt; a transfer member opposed to the image bearing member with the belt therebetween; wherein the transfer member has a contact surface substantially parallel with a surface of the belt and contacted to the belt, and wherein when the belt is moving, the belt rubs the contact surface, and a toner image is transferred from such a part of image bearing member as is opposed to the contact surface; and a supporting member for supporting the transfer member, the supporting member being swingable.

Abstract: Provided is an image forming apparatus whose primary transfer roller is structured in a way as to move from a transfer position along a locus of a rotational motion of a radius r about a rotational center of a photosensitive drum as a rotational axis so that the transfer position is set to a position shifted downstream in a belt moving direction from a position of contact between the photosensitive drum and an intermediate transfer belt by a shift amount f. Accordingly, even when there is an error the upward/downward movement of the primary transfer roller to shift the position of contact, the distance of the primary transfer roller from the circumferential surface of the photosensitive drum is constant, so that the shift amount f which is the tangent of the circumferential surface of the photosensitive drum and the circumferential surface of the primary transfer roller is always set constant.

Abstract: An image forming apparatus including; an image carrier carrying a toner image; a transfer belt making pressure contact with the image carrier through a sheet of paper and transferring the toner image onto the sheet of paper; a plurality of supporting rollers stretching and supporting the transfer belt; and a transfer roller to which transfer electrical current is applied, as well as making pressure contact of the transfer belt with the image carrier from a back surface of the transfer belt, wherein at least one roller of the supporting rollers is formed in an inverted crown shape with a size of the center portion is smaller than a size of the end portion, and the transfer belt is rotationally driven for a prescribed time without applying transfer electrical current both or in either of before and after transfer of a toner image.

Abstract: The present invention is an electroconductive endless belt used in an image forming apparatus in which a decrease with use in the gloss value caused by frictions and the like with papers and cleaning blade is suppressed. In the electroconductive endless belt, the base resin of the electroconductive endless belt comprises a polyalkylene terephthalate resin in combination with a naphthalene ring-containing thermoplastic resin and/or a naphthalene ring-containing thermoplastic elastomer having a melting point higher than that of the polyalkylene terephthalate resin, and the mass ratio of the polyalkylene terephthalate resin to the naphthalene ring-containing thermoplastic resin and/or the naphthalene ring-containing thermoplastic elastomer in the base resin is in the range of 90/10 to 50/50.

Abstract: An image forming apparatus includes a paper cassette feeding a recording material, an image forming unit forming an image on a photosensitive member, a primary transfer roller transferring the image onto an intermediate transfer belt, a secondary transfer roller transferring the image onto the recording material, and a sensor detecting the size of the recording material. The timing of starting feeding the recording material is earlier than the timing of starting forming the image. When image formation on the recording material is started, until the sensor detects the size of the recording material, a plurality of images are formed on the intermediate transfer belt at a first interval according to a predetermined recording material size, and after the sensor detects the size of the recording material, a plurality of images are formed on the intermediate transfer belt at a second interval according to the detected recording material size.

Abstract: An image forming apparatus includes a belt member bearing a toner image, a contact member disposed inside loop formed by the belt member, a rotary pressing member to contact the contact member through the belt member and form a nip between the contact member and the rotary pressing member via the belt member through which a recording medium is conveyed, and a transfer device to transfer the toner image onto the recording medium. An amount of winding of the belt member around the rotary pressing member is changeable between a first state in which the belt member is wound around the rotary pressing member upstream from the nip in the direction of move to the nip and a second state in which the amount of winding of the belt member around the rotary pressing member is reduced from the first state while contacting the belt member.

Abstract: An image forming apparatus includes a plurality of N image carriers including first through Nth image carriers, a transfer unit including an endless transfer belt, a plurality of M belt supporting members including a plurality of first through Nth nip opposing members contacting the inner surface of the endless transfer belt at positions corresponding to where the plurality of N image carriers contacts the outer surface of the endless transfer belt to form N transfer nips thereat, the first opposing member defining a first supported area of the endless transfer belt, a contact and separation mechanism including a retaining unit to move the first supported area of the endless transfer belt into and out of contact with the first image carrier, and a mark detector to detect a plurality of adjacent marks formed at a predetermined pitch in a circumferential direction of the endless transfer belt.

Abstract: There is provided an image forming apparatus which shortens the time taken for circumference detection and measures the circumference at high precision without obstructing downsizing of the apparatus. To accomplish this, the image forming apparatus detects, at an arbitrary timing, the physical pattern of the image-formed surface of a rotation member that changes over time. In the second round, the image forming apparatus detects the second pattern at a timing a predetermined time after the arbitrary timing. By using the detected patterns, the image forming apparatus obtains information associated with the circumference of the rotation member.

Abstract: The presently disclosed embodiments relate generally to an image forming apparatus comprising an overcoat layer disposed directly over in contact with the top circumferential surface of a seamed intermediate transfer belt, and methods for making the same. The overcoat layer, comprising a film forming A-B diblock copolymer and conductive particles dispersion, not only renders the seam area physical/mechanical/electrical continuity for achieving absolute belt surface imageability to function like a seamless intermediate transfer belt, it also provides increased mechanical strength to resist fatigue-bend cracking under normal dynamic intermediate transfer belt machine cycling conditions in the field. The overcoat of this disclosure thus helps to reduce wear and extend service life of the belt.

Abstract: The image forming apparatus includes a transfer rotary member for forming a primary transfer portion (N) between a photosensitive drum and an intermediate transfer belt. The transfer rotary member includes multiple rotary members whose diameters are different, into which the transfer rotary member is divided in a direction orthogonal to a moving direction of the intermediate transfer belt. The transfer rotary member is arranged so as to contact a surface of the intermediate transfer belt on a side opposite to a surface with which multiple photosensitive drums come into contact at the primary transfer portions (N), on a downstream side in the moving direction of the intermediate transfer belt with respect to a contact portion between the intermediate transfer belt and each photosensitive drum, the intermediate transfer belt being arranged so as to protrude on the photosensitive drum side.

Abstract: Provided is a belt driving unit including a plurality of rollers including a driving roller; an endless belt stretched round the rollers; a driving unit that conveys the endless belt by driving the driving roller; a control unit that controls the driving of the driving roller; and a detection unit that detects the position of the endless belt in a widthwise direction perpendicular to the conveying direction of the endless belt. The driving roller includes a first driving roller and a second driving roller. A direction in which the first driving roller forwards the endless belt and a direction in which the second driving roller forwards the endless belt are nonparallel. The control unit controls the position of the endless belt in the widthwise direction by driving the first driving roller and the second driving roller at different speeds on the basis of the detection result of the detection unit.

Abstract: In existing image forming apparatuses, it is difficult to maintain each of a primary transfer member and a secondary transfer member at an optimum potential. An image forming apparatus includes a voltage maintenance element connected to a secondary transfer counter roller and a primary transfer member. The voltage maintenance element maintains each of the secondary transfer counter roller and the primary transfer member at a predetermined potential or higher. By using the voltage maintenance element, each of a secondary transfer roller and the primary transfer member is set to an optimum potential by a single transfer power supply.

Abstract: A voltage maintenance element is connected to a contact member that contacts a primary transfer surface area of an intermediate transfer belt to which toner images are transferred from a plurality of image carriers between stretch members, in such a way as to prevent the electric potential of the intermediate transfer belt from varying between respective stations.

Abstract: An intermediate transfer member that includes a mixture of a poly(amic acid amideimide), a tertiary amine, an optional phosphate ester, an optional polysiloxane or an optional fluoro polymer, and an optional conductive filler component.

Abstract: The image forming apparatus includes an endless and movable transfer material bearing belt, a transfer member, an opposing member and a belt guide member, wherein a conveyance direction of the transfer material in a first area is substantially the same as a conveyance direction of the transfer material in a second area, the first area corresponding to a nip area formed by the opposing member and the transfer member and the second area corresponding to an area in which the belt guide member bringing the transfer material bearing belt and the image bearing belt come into contact with each other. By the virtue of the present invention, a transfer material is restrained from scraping off the leading end of a toner image before the leading end of the toner image enters a transfer nip portion, while suppressing spattering of the toner image on the upstream of the transfer nip portion.

Abstract: A secondary transfer facing roller includes a roller part that has a through-hole penetrating in a rotary shaft line direction at a rotation center position, and a penetrating shaft member penetrating the through-hole of the roller part and spinning the roller part on a surface of the penetrating shaft member. Eccentric cams are fixed to both end regions that are not located in the roller part, so as to rotate integrally with the penetrating shaft member. A position regulating cam and an abutting roller form a gap between the intermediate transfer belt and the secondary transfer roller immediately before a transfer sheet enters a transfer nip part. While the gap is formed, current flows between the intermediate transfer belt and the secondary transfer roller via the position regulating cam and the abutting roller.

Abstract: Flexible members for use in imaging devices which may include a non-ionic surfactant; a fluorinated surfactant; or both.

Abstract: An image forming apparatus capable of reducing deterioration of image quality caused by instantaneous fluctuation of driving speed of an image bearing member and intermediate transfer member, the apparatus including: an image bearing member; a primary transfer section to transfer toner image from the image bearing member onto an intermediate transfer member; a secondary transfer section, including a secondary transfer member to secondarily transfer the toner image from the intermediate transfer member onto a recording medium, capable of bringing the secondary transfer member into contact with the intermediate transfer member under pressure and then releasing the contact; a motor to drive the secondary transfer member, and a driving section configured to drive the secondary transfer section so as to bring the secondary transfer member into contact with the intermediate transfer member with pressure and then to release the contact, wherein the motor is not provided inside the secondary transfer section.

Abstract: An image forming apparatus including a transfer belt on which an image is transferred, a belt suspension roller that suspends the transfer belt, a transfer roller that is arranged to face the belt suspension roller with the transfer belt in between and includes a shaft portion and a concave portion formed in a shaft direction, and a support member that is arranged on the shaft portion of the transfer roller and includes a first circumferential portion arranged in the concave portion as seen from a shaft direction of the transfer roller, a second circumferential portion arranged at one side of the concave portion in a rotation direction, and a third circumferential portion arranged at the other side of the concave portion in the rotation direction.

Abstract: A surface protective film includes a self-healing urethane resin and a conductive powder. In the surface protective film, the content of the conductive powder is about 5 vol % or more and about 25 vol % or less relative to the volume of the urethane resin.

Abstract: An image forming apparatus capable of improving the reliability of intermediate transfer belt shift control and attaining a high quality image. The image forming apparatus includes an intermediate transfer belt onto which a toner image is transferred and formed, a shift position detecting sensor that detects a shift position of the belt, a shift control roller that changes the shift position of the belt, and an angle adjustment cam and an angle adjustment arm that correct an inclination angle of the roller. An amount of correction for the inclination angle is calculated by an ASIC based on the belt shift position detected by the sensor. In a Kf multiplier and a Kr multiplier, coefficient values used for the calculation of the amount of correction for the inclination angle can variably be changed independently for respective directions of control for the roller inclination angle.

Abstract: An endless belt for an image-forming apparatus includes, as an outermost layer, a resin layer having substantially hemispherical protrusions distributed over an outer surface thereof.

Abstract: An image forming apparatus includes a movable belt; a transfer member opposed to the image bearing member with the belt therebetween; wherein the transfer member has a contact surface substantially parallel with a surface of the belt and contacted to the belt, and wherein when the belt is moving, the belt rubs the contact surface, and a toner image is transferred from such a part of image bearing member as is opposed to the contact surface; and a supporting member for supporting the transfer member, the supporting member being swingable.

Abstract: A transfer belt unit satisfies the following conditions. An intermediate transfer belt has a thickness not less than 100 micrometers and not more than 200 micrometers, a tension not less than 80 N/m and not more than 180 N/m, and a tensile elastic modulus not less than 1000 megapascals and not more than 2000 megapascals. A secondary-transfer bias roller has an Asker C hardness not less than 35 degrees and not more than 50 degrees. Stretching rollers for stretching the intermediate transfer belt have an outer diameter not less than 6 millimeters.

Abstract: An image forming apparatus is operable in a mode in which a speed of an intermediary transfer belt is changed after all of the toner images are primary-transferred onto the intermediary transfer belt, and the toner image primary-transferred on the intermediary transfer belt is passed through a secondary transfer position and primary transfer position in this order to reach the secondary transfer position, where the toner image is secondary transferred onto the transfer material, and a controller for making, before the image forming apparatus is operated in the mode to change the speed of the intermediary transfer belt, a potential difference between the intermediary transfer belt and the photosensitive member at the primary transfer position smaller than a potential difference between the intermediary transfer belt and the photosensitive member when the toner image is primary transferred from the photosensitive member onto the intermediary transfer belt.