An image forming apparatus (1) includes a process unit (P) which is configured to be turned upward and then detached from an apparatus main body (3). The process unit (P) includes: a photosensitive drum (47); a developing device (51) which forms a developing nip area; a guide member (81) which comes into contact with an upper surface of a sheet and guides the sheet; and a seal member (91) supported between the developing device (51) and the guide member (81) in a turnable manner, wherein the seal member (91) opens a gap between the developing device (51) and the guide member (81) in a state where the process unit (P) is attached to the apparatus main body (3), and when the process unit (P) is turned upward, the seal member (91) is turned to close the gap between the developing device (51) and the guide member (81).

An image forming apparatus (1) includes a process unit (P) which is configured to be turned upward and then detached from an apparatus main body (3). The process unit (P) includes: a photosensitive drum (47); a developing device (51) which forms a developing nip area; a guide member (81) which comes into contact with an upper surface of a sheet and guides the sheet; and a seal member (91) supported between the developing device (51) and the guide member (81) in a turnable manner, wherein the seal member (91) opens a gap between the developing device (51) and the guide member (81) in a state where the process unit (P) is attached to the apparatus main body (3), and when the process unit (P) is turned upward, the seal member (91) is turned to close the gap between the developing device (51) and the guide member (81).

An image-forming apparatus includes a photosensitive drum, a developing roller, a cam, a switching mechanism, a cam follower, and a controller for controlling the switching mechanism to control rotation of the cam. The cam is rotatable to move the developing roller between a contact position in contact with the photosensitive drum and a separated position in separation from the photosensitive drum. To maintain the developing roller at the contact position after being moved from the separated position, the cam is rotated to move the cam follower from a first holding surface to a second holding surface of the cam through a second guide surface, and is stopped rotating to hold the cam follower in contact with a first guide surface of the cam at a position closer to the first holding surface than to the second holding surface.

Provided is an electrophotographic member including: an electroconductive substrate; and an elastic layer on the substrate, the elastic layer constituted by a single layer, the elastic layer containing a silicone rubber having a dimethylsiloxane structure, wherein when a peak top temperature of an ion thermogram derived from the dimethylsiloxane structure, the ion thermogram being measured from a first sample sampled from a first region having a thickness of 0.5 m from a first surface of the elastic layer toward a second surface thereof, is represented by T1, and a peak top temperature of an ion thermogram derived from the dimethylsiloxane structure, the ion thermogram being measured from a second sample sampled from a second region corresponding to a thickness of 1.0 m to 1.5 m from the second surface toward the first surface, is represented by T2, T1 and T2 satisfy a relationship of T1>T2.

A charging member includes a conductive substrate, an elastic layer disposed on the conductive substrate, and a surface layer disposed on the elastic layer. Regarding the surface of the surface layer, in the axial direction, the ratio of the mean spacing of profile irregularities Sm to the ten-point mean roughness Rz and the reduced peak height Spk respectively satisfy 15Sm/Rz35 and Spk5 m.

A charging member includes a conductive substrate, an elastic layer disposed on the conductive substrate, and a surface layer disposed on the elastic layer. Regarding the surface of the surface layer, in the axial direction, the ratio of the mean spacing of profile irregularities Sm to the ten-point mean roughness Rz and the reduced peak height Spk respectively satisfy 15Sm/Rz35 and Spk5 m.

An image-forming apparatus includes a photosensitive drum, a developing roller, a cam, a switching mechanism, a cam follower, and a controller for controlling the switching mechanism to control rotation of the cam. The cam is rotatable to move the developing roller between a contact position in contact with the photosensitive drum and a separated position in separation from the photosensitive drum. To maintain the developing roller at the contact position after being moved from the separated position, the cam is rotated to move the cam follower from a first holding surface to a second holding surface of the cam through a second guide surface, and is stopped rotating to hold the cam follower in contact with a first guide surface of the cam at a position closer to the first holding surface than to the second holding surface.

A secondary transfer portion includes a transfer roller, a fixing member, a movable member, and a detector. The transfer roller is configured to rotate about an axis thereof when the secondary transfer portion is attached to an apparatus body. The fixing member is fixed to the axial end portion of the transfer roller. The movable member is caught on the fixing member. The detector is configured to indicate different detection states depending on a position of the movable member. The fixing member and the movable member are connected to each other through a guide mechanism (a guide groove and a guide protrusion) that is configured to move the movable member in an axial direction of the transfer roller. The movable member is moved to a detection position of the detector by rotation of the transfer roller.

A secondary transfer portion includes a transfer roller, a fixing member, a movable member, and a detector. The transfer roller is configured to rotate about an axis thereof when the secondary transfer portion is attached to an apparatus body. The fixing member is fixed to the axial end portion of the transfer roller. The movable member is caught on the fixing member. The detector is configured to indicate different detection states depending on a position of the movable member. The fixing member and the movable member are connected to each other through a guide mechanism (a guide groove and a guide protrusion) that is configured to move the movable member in an axial direction of the transfer roller. The movable member is moved to a detection position of the detector by rotation of the transfer roller.

A unit accommodation apparatus includes a first unit and a second unit that are to be installed into and removed from an apparatus body through an opening in an installation-removal direction and are held by a unit holder. The unit holder includes a first positioner that is disposed opposite one lateral end of the first unit and the second unit and is detachably attached to the first unit and the second unit. A second positioner is disposed opposite another lateral end of the first unit and the second unit and holds the first unit and the second unit in a state in which the first unit and the second unit are detachably attached to the second positioner. The first positioner and the second positioner secure a relative position of the first unit relative to the second unit in a direction parallel to a hypothetical orthogonal plane perpendicular to the installation-removal direction.