Abstract: A transfer unit includes, as transfer rollers, a first roller and a second roller of which the latter has an elastic layer larger in an axial direction than that of the former, a first bearing member, a second bearing member, a roller holder, a first urging member, a second urging member, a switching cam, a transfer voltage power supply, and a driving mechanism. By rotating the roller holder, one of the first and second rollers is arranged opposite an image carrying member and, by rotating the switching cam, the first or second roller arranged opposite the image carrying member is arranged either at a reference position at which, by being kept in pressed contact with the image carrying member, the first or second roller forms a transfer nip or at a released position at which the first or second roller lies away from the image carrying member.

Abstract: An image forming apparatus includes a belt, tension rollers, an outer member, a pressing member, a moving mechanism, and an attachable unit. The belt bears a toner image and the tension rollers stretch the belt around rollers. The toner image is transferred at the outer member from the belt onto a recording material. The moving mechanism moves the pressing member to press an inner surface of the belt toward an outer surface side. The attachable unit includes the pressing member or the belt and attaches to and detaches from the image forming apparatus. A mode is executed in which the pressing member presses the belt to transfer the toner image onto the recording material. Information is stored based on an individual difference of the attachable unit related to a setting of a moving mechanism position in executing the mode, where the setting is based on the stored information.

Abstract: An intermediate transfer unit includes an intermediate transfer belt, a driving roller, a tension roller, and a roller supporting frame. The roller supporting frame includes first and second supporting frames, and has a coupling portion formed on it. The coupling portion includes a rotary shaft and a shaft hole. The roller supporting frame shifts from a first state to a second state by rotating the first supporting frame in the forward direction to have the intermediate transfer belt wound around it. The rotary shaft includes a projection. A shaft hole has a restricting wall portion. As the first supporting frame in the second state rotates in the forward direction, the projection makes contact with the restricting wall portion to restrict rotation of the first supporting frame in the forward direction.

Abstract: An image forming apparatus is capable of suppressing deterioration in accuracy of control for switching a motor from forward to reverse rotation in a configuration in which a coupling having play in a rotation direction is interposed in a drive train between the motor and a driven member. The image forming apparatus includes a motor that rotationally drives a photosensitive drum and a developing sleeve; a coupling interposed in a drive train between the motor and the developing sleeve and/or a drive train between the motor and the photosensitive drum and having play in a rotation direction; and a CPU that controls the motor. The CPU rotates the motor forward at a speed V1 at the time of image formation, stops the motor after the end of the image formation, rotates the motor forward at a speed V2 lower than the speed V1, and then reversely rotates the motor.

Abstract: A charging device includes: a charging roller to charge a surface of the image carrier by rotating in contact with an image carrier; a cleaning roller to clean a surface of the charging roller by rotating in contact with the charging roller; a bearing to hold the charging roller and the cleaning roller so that a distance between an axis of the charging roller and an axis of the cleaning roller is constant; and a biaser to apply a biasing force to the bearing in a direction to bring the charging roller into press contact with the image carrier, wherein the bearing has a first bearing to support the axis of the cleaning roller and a second bearing to support the axis of the charging roller, and the first bearing is disposed inward from the second bearing in a roller axial direction of the cleaning roller and the charging roller.

Abstract: An image forming apparatus includes a first image forming portion, a second image forming portion, a belt, a charging voltage applying portion, and a transfer voltage applying portion. With respect to a movement direction of a recording material, the first image forming portion is provided upstream of the second image forming portion. In an image forming operation, a potential difference between a first transfer voltage and a potential at a first transfer portion, which is formed on a first image bearing member and does not form the image, is greater than a potential difference between a second transfer voltage and a potential at a second transfer portion, which is formed on a second image bearing member and does not form an image.

Abstract: A control portion controls a change mechanism so as to pass through a third stretched form in switching a stretched form of a belt member from a second stretched form to a first stretched form. The first stretched form is a stretched form enabling a toner image to be transferred from a photosensitive drum to the belt member by positioning a transfer member at a first position and a separation roller at a second position. The second stretched form is a stretched form of separating each of the transfer member and the separation roller from a transfer surface toward an opposite side of the photosensitive drum. The third stretched form is a stretched form in which the transfer member is positioned at the first position, and the separation roller is positioned at a third position away from the transfer surface toward the opposite side of the photosensitive drum.

Abstract: An image forming apparatus includes a photosensitive drum, a development roller configured to supply developer to the photosensitive drum, a transfer roller configured to transfer a developer image formed on the photosensitive drum to a recording material, and a cleaning roller being in contact with the photosensitive drum, configured to clean a part of the recording material adhered to the photosensitive drum, wherein a diameter of the transfer roller is greater than a diameter of the development roller and the diameter of the transfer roller is greater than a diameter of the cleaning roller.

Abstract: An image forming apparatus includes an image bearing member, a transfer member, a voltage applying portion applying a voltage to the transfer member, and a controller. The controller starts a control operation by applying a control voltage to the transfer member before a toner image is transferred to a transferred member from the image bearing member. On the basis of a coverage ratio indicating a ratio occupied by an image region per predetermined area regarding the toner image transferred to the transferred member from the image bearing member, the controller determines execution or non-execution of the control operation capable of being started before the toner image is transferred to the transferred member.

Abstract: A cleaning device includes a housing, a cleaning blade, a toner conveyance path, a conveyance screw, and a first flicker. The conveyance screw includes a rotary shaft and a helical vane. The first flicker includes a first base portion and a plurality of first contact pieces and uses the first contact pieces to press the conveyance screw in a first direction away from a bottom part of the toner conveyance path. The first base portion includes a secured portion and a blade opposed portion. The first contact pieces are connected to an upper end part of the blade opposed portion. An elastic member is disposed between the cleaning blade and the blade opposed portion.

Abstract: A transfer unit includes a first roller, a second roller, a first bearing member, a second bearing member, a roller holder, a first urging member, a second urging member, a first switching cam, a second switching cam, and a driving mechanism. The first and second switching cams have first and second guide holes with which first and second engaging portions formed on the first and second bearing members engage respectively. By rotating the roller holder, one of the first and second rollers is arranged opposite an image carrying member and, by rotating the first and second switching cams to change engaging positions of the first and second engaging portions respectively, the first or second roller is arranged either at a reference position at which it is kept in pressed contact with the image carrying member or at a released position.

Abstract: A transfer unit includes, as transfer rollers, first and second rollers of which the second has an elastic layer larger in an axial direction than the first, first and second bearing members, a roller holder, first and second urging members, a switching cam, a driving mechanism, and a first pre-transfer guide. By rotating the roller holder, the first or second roller is arranged opposite an image carrier and, by rotating the switching cam, the first or second roller arranged opposite the image carrier is arranged selectively either at a reference position where the first or second roller is in pressed contact with the image carrier or at a released position where the first or second roller lies away from the image carrier. With the first or second roller arranged at the reference position, the first pre-transfer guide is arranged at a first guide position.

Abstract: A transfer unit includes first and second rollers of which the second roller has an elastic layer larger in the axial direction than the first roller, a roller holder, and a switching cam. One of the first and second rollers is, by rotating the roller holder, arranged opposite an image carrying member and, by rotating the switching cam, arranged selectively either at a reference position to form a transfer nip or at a released position to lie away from the image carrying member. Let a length of the elastic layer of the first roller in the axial direction, a width of an effective image area on the image carrying member to which a toner image can be transferred, and a width of a recording medium of a maximum size allowing transfer using the first roller be L1, L3, and L4 respectively, L4<L1?L3?5 mm is fulfilled.

Abstract: A cleaning body includes a core, a foam elastic layer that is disposed to be wound around an outer peripheral surface of the core in a helical shape from one end to the other end of the core, and an adhesive layer that adheres the core and the foam elastic layer, in which a diameter of a tip portion of a cell skeleton protruding on a surface of the foam elastic layer is equal to or less than 50 ?m, and in a case where an inner peripheral length of the foam elastic layer in a cross section of the core in a radial direction is X (mm) and a thickness of the foam elastic layer is Y (mm), a value of X×Y2 is equal to or greater than 45.

Abstract: A cleaning device includes a cleaning blade, a supporting member, a housing, a pressing member, and a sealing member. The supporting member is a metal member extended in a longitudinal direction of the cleaning blade. The supporting member includes a first flat surface portion formed along a widthwise direction, a curved surface portion bent toward a rotatable member with respect to a thickness direction of the cleaning blade, and a second flat surface portion formed along the thickness direction of the cleaning blade. As viewed in the longitudinal direction, a swing center of the supporting member is positioned on a rotation center side of the rotatable member relative to a plane including the first flat surface portion and relative to a plane including the second flat surface portion. The sealing member is provided in contact with the curved surface portion and seals between the supporting member and the housing.

Abstract: A charging device includes a charging member that is rotatable and contacts and electrically charges a surface of a charging target member; and a cleaning member that is rotatable and cleans a surface of the charging member, wherein the cleaning member includes a core bar extending in a lengthwise direction, a foam member that is helically wound around the core bar while forming a gap in the lengthwise direction and contacts the charging member, and a first adhesive agent that is provided between the foam member and the core bar, the first adhesive agent contacting a part of the foam member and another part of the foam member that are formed to adjoin each other in the lengthwise direction via the gap.

Abstract: A cleaning device includes a cleaner that cleans a body to be cleaned, wherein the cleaner includes: an elastic member in which a contact portion in contact with the body to be cleaned is formed in an uneven shape continuous in a predetermined direction; and a support member that supports the elastic member, and the cleaner is configured so that a contact pressure of the elastic member to the body to be cleaned is constant in the predetermined direction.

Abstract: An image forming apparatus includes an image forming unit and a belt conveyance apparatus. The belt conveyance apparatus includes a transfer belt, a tension roller, a movement mechanism, and a drive unit. A toner image on an image bearing member is transferred to the transfer belt in tension from the tension roller. The movement mechanism moves the tension roller to apply tension to, and release tension from, the transfer belt. The drive unit is disposed in a width direction and drives the transfer belt. The movement mechanism includes an attachment portion disposed on a side opposite the drive unit in the width direction and to which a handle member that operates the movement mechanism is detachably attached. The movement mechanism is configured such that the belt conveyance apparatus is attached to an image forming apparatus body in a state in which the handle member is detached from the attachment portion.

Abstract: An image forming apparatus includes a controller and a transfer power supply portion configured to output a transfer voltage to a transfer portion so as to transfer a toner image onto a recording material. The transfer power supply portion superimposes a voltage output from a first power supply portion and a voltage output from a second power supply portion to output a superimposed voltage to the transfer portion. The first power supply portion includes a transformer including a primary coil and a secondary coil, and a rectifier circuit portion. The rectifier circuit portion includes a plurality of diodes and a plurality of capacitors. A capacitance of a predetermined capacitor to be charged by a half-wave rectified voltage of an AC voltage generated in the secondary coil is larger than a capacitance of a capacitor to be charged by a voltage higher than the half-wave rectified voltage.

Abstract: An imaging system includes a transfer roller having a surface to transfer a toner image onto a print medium during a printing operation of the imaging system, a conductive device to contact the surface of the transfer roller, a power source electrically connected to the conductive device, a resistance measurement device, and a controller. The transfer roller rotates according to a printing speed of the printing operation. The power source supplies a bias to the transfer roller through the conductive device during the printing operation. The resistance measurement device measures an electrical resistance of the print medium. The controller reduces the printing speed based on the electrical resistance measured by the resistance measurement device.