An image forming apparatus, including a main chassis having a discharge tray and a switchback tray in an upper position with respect to the discharge tray; an image forming unit; a discharge roller to discharge a recording sheet conveyed through the image forming unit onto the discharge tray; a duplex conveyer to invert the sheet and convey the inverted sheet to return to the image forming unit; and a switchback roller being rotatable in a normal direction to convey the sheet toward the switchback tray and a reverse direction to convey the sheet to the duplex conveyer; is provided. The main chassis includes a pair of walls, each of which extends in a vertical direction and in a conveying direction of the sheet and is arranged in adjacent to the switchback tray such that the switchback tray is interposed between the pair of walls.

A sheet type determining device including a guide that guides a sheet along a sheet conveyance path to a destination. The sheet conveyance path is between a first guide surface and a second guide surface facing each other across an interval. The sheet type determining device further includes a determiner that determines a sheet type when the sheet is in the sheet conveyance path, without having contact with the sheet in conveyance, and one or more regulators that regulate a displacement range of the sheet at a determining position, the displacement range being in a direction of the interval of the first and the second guide surfaces. Each of the regulators is a member that protrudes in an arc shape from the first or the second guide surface toward the guide surface opposite, and is spaced from the guide surface or another one of the regulators opposite.

A sheet type determining device including a guide that guides a sheet along a sheet conveyance path to a destination. The sheet conveyance path is between a first guide surface and a second guide surface facing each other across an interval. The sheet type determining device further includes a determiner that determines a sheet type when the sheet is in the sheet conveyance path, without having contact with the sheet in conveyance, and one or more regulators that regulate a displacement range of the sheet at a determining position, the displacement range being in a direction of the interval of the first and the second guide surfaces. Each of the regulators is a member that protrudes in an arc shape from the first or the second guide surface toward the guide surface opposite, and is spaced from the guide surface or another one of the regulators opposite.

An image forming apparatus includes an image forming portion, a reversing portion configured to reverse the sheet received through a first feeding passage by feeding the sheet in a first direction and then in a second direction opposite to the first direction, a sheet feeding portion provided in a second feeding passage branching from the first feeding passage on a side upstream of the reversing portion with respect to the first direction, a first guiding surface forming the second feeding passage for guiding a first surface of the sheet fed by the feeding portion, and a second guiding surface for guiding a second surface, opposite from the first surface, of the sheet fed from the reversing portion in the second direction. The second guiding surface is movable with movement of the first guiding surface for opening the second feeding passage.

A sheet conveyance device includes a conveyance roller pair to convey a sheet, a skew correction roller pair to correct a skew of the sheet in a state in which the skew correction roller pair is being stopped, first and second conveyance guides, and a protrusion. The first conveyance guide includes a bend contact portion to come into contact with a portion forming a bend on the first surface of the sheet. The second conveyance guides the sheet. The protrusion is disposed between the skew correction roller pair and the bend contact portion to come into contact with the first surface of the sheet. The protrusion protrudes toward the second conveyance guide from the first conveyance guide in a manner as to intersect with a straight line connecting two nip portions and the bend contact portion in a cross section perpendicular to a width direction.

A sheet conveyance device includes a conveyance roller pair to convey a sheet, a skew correction roller pair to correct a skew of the sheet in a state in which the skew correction roller pair is being stopped, first and second conveyance guides, and a protrusion. The first conveyance guide includes a bend contact portion to come into contact with a portion forming a bend on the first surface of the sheet. The second conveyance guides the sheet. The protrusion is disposed between the skew correction roller pair and the bend contact portion to come into contact with the first surface of the sheet. The protrusion protrudes toward the second conveyance guide from the first conveyance guide in a manner as to intersect with a straight line connecting two nip portions and the bend contact portion in a cross section perpendicular to a width direction.

A sheet conveyance device includes a conveyance roller pair. A skew correction roller pair conveys the sheet after contacting two nip portions, and a sheet skew is corrected in a state in which the skew correction roller pair is being stopped. The sheet having a toner image is bent by a first conveyance guide such that a sheet first surface becomes an inside surface. The sheet is bent by the first and second conveyance guides to cause the sheet first surface to be the inside surface and a sheet second surface to be an outside surface. The skew correction roller pair includes two first rotary members of a first roller. A second roller and the two first rotary members form the two nip portions. The second roller and the first conveyance guide contact the sheet first surface. The first roller and the second conveyance guide contact the sheet second surface.

A suction device includes a suction hole member including a plurality of suction holes, a suction pump connected to each of the plurality of suction holes, the suction pump configured to suction an air through the plurality of suction holes of the suction hole member to suction a suction target to the suction hole member, and a suction state detector configured to detect a suction state of at least one of the plurality of suction holes corresponding to an end of the suction target suctioned to the suction hole member.

A conveying device includes a first guide section, a second guide section, and an urging section. The second guide section has a guide center portion and pivots about the guide center portion. The second guide section is pivotable between a guide position and a separation position. The guide position is a position in which the second guide section is located when a conveyance path of a sheet is formed between the second guide section and the first guide section. When the second guide section is in the guide position, the urging section urges the second guide section in a first pivot direction.

A conveying device includes a first guide section, a second guide section, and an urging section. The second guide section has a guide center portion and pivots about the guide center portion. The second guide section is pivotable between a guide position and a separation position. The guide position is a position in which the second guide section is located when a conveyance path of a sheet is formed between the second guide section and the first guide section. When the second guide section is in the guide position, the urging section urges the second guide section in a first pivot direction.