Abstract: An optical sensor irradiates a control toner image formed on an intermediate transfer belt with light and detects reflection light of the light. A controller executes an abnormality diagnosis mode in a case where change in the phase of a cam is not detected by a phase detection portion until an elapse of a predetermined time or more since a start of output of a driving signal for driving a separation mechanism. In execution of the abnormality diagnosis mode, the controller outputs the driving signal for driving the separation mechanism, and is capable of outputting information about an abnormality of the phase detection portion and information about an abnormality of the separation mechanism and/or a driving unit on a basis of a detection result of the optical sensor that is obtained in a case where the light is radiated from the optical sensor while the driving signal is output.

Abstract: An optical sensor irradiates a control toner image formed on an intermediate transfer belt with light and detect refection light of the light. A controller executes an abnormality diagnosis mode in a case where change in the phase of a cam is not detected by a phase detection portion until an elapse of a predetermined time or more since a start of output of a driving signal for driving a separation mechanism. In execution of the abnormality diagnosis mode, the controller outputs the driving signal for driving the separation mechanism, and is capable of outputting information about an abnormality of the phase detection portion and information about an abnormality of the separation mechanism and/or a driving unit on a basis of a detection result of the optical sensor that is obtained in a case where the light is radiated from the optical sensor while the driving signal is output.

Abstract: An image forming apparatus includes an endless belt; an image bearing member that bears a toner image and contacts with the outer circumferential surface of the belt at a transfer position for transferring the toner image to the belt, the transfer position being disposed downstream; a transfer roller configured to transfer the toner image from the image bearing to the belt and contact with an inner circumferential surface of the belt at a contact position, the contact position not overlapping with the transfer position as viewed from the thickness direction of the belt; a biasing member that biases the transfer roller toward the inner circumferential surface of the belt, and a position of the transfer roller is set to a balanced position between a biasing force by the transfer roller pressing the inner circumferential surface of the belt and the drag received by the transfer roller from the belt.

Abstract: An image forming apparatus includes a guiding portion that acts on a shutter member to open and close the shutter member when a unit, including the shutter member, is mounted to and dismounted from a main assembly. The guiding portion includes an opening operating portion that moves the shutter member from the closing position to the opening position in interrelation with an inserting operation of the unit, a closing operating portion that moves the shutter member from the opening position to the closing position in interrelation with an extracting operation of the unit, and a shutter closing portion contacted to the shutter member at a position upstream of the opening operating portion and the closing operating portion, with respect to an inserting direction of the unit relative to the guiding portion, to move the shutter member from the opening position to the closing position in interrelation with the inserting operation.

Abstract: A mounting portion to and from which a unit provided with a belt cleaning device is inserted and extracted includes an opening operating portion for contacting a shutter member to move a shutter member from a closing position to an opening position in interrelation with, a closing operating portion for contacting the shutter member to move the shutter member from the opening position to the closing position in interrelation with an extracting operation, and a shutter closing portion for contacting the shutter member at a position upstream of the shutter opening and closing portions in the inserting direction to move said shutter member from the opening position to the closing position.

Abstract: An image forming apparatus includes: an endless belt; an image bearing member that bears a toner image and contacts with the outer circumferential surface of the belt at a transfer position for transferring the toner image to the belt, the transfer position being disposed downstream; a transfer roller configured to transfer the toner image from the image bearing to the belt and contact with an inner circumferential surface of the belt at a contact position, the contact position does not overlap with the transfer position as viewed from the thickness direction of the belt; a biasing member that biases the transfer toward the inner circumferential surface of the belt, and a position of the transfer roller is set to a balanced position between a biasing force by the transfer roller pressing the inner circumferential surface of the belt and the drag received by the transfer roller from the belt.

Abstract: An image forming apparatus includes a rotatable first coupling provided at a side surface of an engaging portion with a taper surface, and a unit detachably mountable in a second direction crossing with the first direction. The unit includes a second coupling, a driven member and a releasing member. The second coupling includes at an end portion thereof a portion-to-be-engaged engageable with the engaging portion to transmit the driving force, and the driven member receives the driving force from the second coupling. When the unit is disengaged from the main assembly, the releasing member is moved in the second direction in contact with the taper surface to move the first coupling away from the second coupling to effect disengagement between the engaging portion and the portion-to-be-engaged.

Abstract: A belt module including a replacement belt member to be supported by a supporting portion of an image forming apparatus includes an endless belt member, and a protecting sheet, provided along an inner peripheral surface of the belt member, for suppressing deformation of the belt member by an external force and for protecting the inner peripheral surface of the belt member.

Abstract: An image forming apparatus includes a slider movable from a first position to a second position against a spring force for urging a primary transfer roller to an intermediary transfer belt to space the primary transfer roller from the intermediary transfer belt. An assisting mechanism assists the movement of the slider in a first direction. The assisting mechanism includes vertical and horizontal sliders which cause to apply the urging force of a compression spring to the slider as an urging force in the first direction, from a third position which is between the first position and the second position.

Abstract: An image forming apparatus includes a slider movable from a first position to a second position against a spring force for urging a primary transfer roller to an intermediary transfer belt to space the primary transfer roller from the intermediary transfer belt. An assisting mechanism assists the movement of the slider in a first direction. The assisting mechanism includes vertical and horizontal sliders which cause to apply the urging force of a compression spring to the slider as an urging force in the first direction, from a third position which is between the first position and the second position.

Abstract: A belt module including a replacement belt member to be supported by a supporting portion of an image forming apparatus includes an endless belt member, and a protecting sheet, provided along an inner peripheral surface of the belt member, for suppressing deformation of the belt member by an external force and for protecting the inner peripheral surface of the belt member.

Abstract: An image forming apparatus includes a first coupling rotatable, the first coupling being provided at a side surface of the engaging portion with a taper surface having a diameter which increases in the first direction from a free end portion toward a driving source; and a unit detachably mountable in a second direction crossing with the first direction, the unit including a second coupling, a driven member and a releasing member. The second coupling includes at an end portion thereof a portion-to-be-engaged engageable with the engaging portion to transmit the driving force, the driven member receives the driving force from the second coupling, and when the unit is disengaged from the main assembly, the releasing member is moved in the second direction in contact with the taper surface to move the first coupling away from the second coupling to effect disengagement between the engaging portion and the portion-to-be-engaged.

Abstract: A belt unit includes an endless belt; multiple rollers including a tension roller that applies tension to the belt; a frame to which the multiple rollers are attached; bearing members which are movably attached to the frame and at least one of which is detachable from the frame; and urging units that urge the bearing members from the inner-peripheral-surface side to the outer-peripheral-surface side of the belt. The detachable bearing member includes a hole part that receives a rotation shaft of the tension roller and that rotatably supports the rotation shaft; and a guide surface that guides the shaft to an opening of the hole part while the bearing member is moving toward the frame against the urging force of the urging unit to be attached to the frame.

Abstract: A belt unit, in which a belt can be detached by detaching a tension roller from a frame by detaching at least one of bearing members from the frame in a state where the belt is stretched around multiple rollers, includes restriction parts that restrict the position of an end of the tension roller in a state where the belt is stretched around the multiple rollers and the bearing member is detached from the frame, the end being located adjacent to the bearing member.

Abstract: An image forming apparatus assembly includes a main body, and a belt unit mounted to the main body and including an endless belt, a plurality of rollers including a first roller configured to apply a driving force to the belt and to stretch the belt, and a second roller around which the belt is wound with a wrapping angle not less than 90° and configured to stretch the belt, a frame configured to integrally support the rollers, a first engaging portion disposed in the frame and configured to position the first roller to the main body, and a second engaging portion disposed in the frame and configured to position the second roller to the main body. In addition, a guide member is configured to guide the belt unit and disposed in the main body, and including a first engaged portion engaged with the first engaging portion and a second engaged portion engaged with the second engaging portion.

Abstract: An endless belt includes an endless belt body, and a plurality of first tapes each wound around an outer peripheral surface of the belt body. Each of the first tapes has a length shorter than a full circumference of the endless belt, and the first tapes are superposedly applied onto the belt body so that positions of first edges of the first tapes and positions of second edges of the first tapes are different from each other, respectively. A recessed portion is formed in a region between the first edges and the other edges second. In addition, a second tape having a length longer than the length of a full circumference of the endless belt is wound around the first tapes so as to extend along the recessed portion, wherein a winding end edge of the second tape overlaps a winding start edge of the second tape.

Abstract: A belt unit, in which a belt can be detached by detaching a tension roller from a frame by detaching at least one of bearing members from the frame in a state where the belt is stretched around multiple rollers, includes restriction parts that restrict the position of an end of the tension roller in a state where the belt is stretched around the multiple rollers and the bearing member is detached from the frame, the end being located adjacent to the bearing member.

Abstract: A belt unit includes an endless belt; multiple rollers including a tension roller that applies tension to the belt; a frame to which the multiple rollers are attached; bearing members which are movably attached to the frame and at least one of which is detachable from the frame; and urging units that urge the bearing members from the inner-peripheral-surface side to the outer-peripheral-surface side of the belt. The detachable bearing member includes a hole part that receives a rotation shaft of the tension roller and that rotatably supports the rotation shaft; and a guide surface that guides the shaft to an opening of the hole part while the bearing member is moving toward the frame against the urging force of the urging unit to be attached to the frame.

Abstract: An endless belt includes: an endless belt body; and a tape which is wound around the endless belt body through more than full circumference on an outer peripheral surface of each of end portions of the endless belt body with respect to a widthwise direction crossing a circumferential direction of the endless belt body and which is provided so that said tape overlaps a winding start portion with a slack.

Abstract: In a configuration in which a carriage jumps at an end of a screw without using a sensor for detecting a position, when a load for moving the carriage in a longitudinal direction is increased, the carriage jumps at an unintended position of a charging wire. An urging member is regulated not to be displaceable greater than a difference between a concave portion and a convex portion of the screw when the regulation member is at a regulation position, and is displaceable greater than the difference between the concave portion and the convex portion of the screw when the regulation member is at a retreat position.