An image forming apparatus includes an image forming unit configured to form an image on a sheet, a duplex conveyance path through which the sheet having the image formed by the image forming unit on a first side passes when an image is formed on a second side that is a back side of the first side, a guiding member provided along the duplex conveyance path, a reversing roller pair capable of rotating in a forward direction and in a reverse direction, h, and a conveyance roller pair provided on the duplex conveyance path, wherein at least one of the reversing roller pair is inclined to the width direction so that, in the width direction, the side end of the sheet being conveyed by the reversing roller pair rotating in the reverse direction moves closer to the contact portion.

An image forming apparatus includes a process unit configured to form a toner image on a sheet, a fuser configured to heat the sheet passed through the process unit thereby fixing the toner image onto the sheet, a re-conveyor configured to convey the sheet passed through the fuser to the process unit, and a controller configured to perform particular duplex printing including controlling, when a temperature of the fuser is a first temperature, the re-conveyor to convey the sheet passed through the fuser to the process unit in a first period of time, and controlling, when the temperature of the fuser is a second temperature higher than the first temperature, the re-conveyor to convey the sheet passed through the fuser to the process unit in a second period of time longer than the first period of time.

An image forming apparatus includes an image forming unit configured to form an image on a sheet, a reversing unit configured to convey a sheet conveyed from the image forming unit in a first direction, stop the conveyance, and then convey the sheet in a second direction, which is opposite to the first direction, an image detection unit disposed to detect at least a portion of the image on the sheet stopped by the reversing unit, and a control unit configured to control the reversing unit and the image detection unit. The control unit is configured to detect the image on the sheet by the image detection unit while the sheet conveyance is stopped by the reversing unit.

An image forming apparatus includes a primary transfer unit, a secondary transfer unit, a registration roller pair placed upstream of the secondary transfer unit in a sheet transport direction, and a drive unit driving the registration roller pair. In addition, a detection sensor unit is placed on a sheet transport path downstream of the secondary transfer unit and detects a sheet transported after a toner image is secondary transferred by the secondary transfer unit, and a transport unit transports the sheet after the secondary transfer. A control unit stops the drive unit when it determines absence of the sheet on the sheet transport path based on a signal from the detection sensor unit when a predetermined time based on an interval of time, which is from when the control unit controls the drive unit and starts to transport the sheet by the registration roller pair to when a leading edge of the sheet reaches the detection sensor unit, has elapsed, or when an interval of time, which is taken from when the control unit controls the drive unit and starts to transport the sheet by the registration roller pair to when the leading edge of the sheet reaches the transport unit, has elapsed.

To provide an image forming apparatus in which the paper is cooled early by blowing air to the paper in the conveying path so as to prevent a sticking phenomenon on a paper output tray while paper turning, paper folding, paper breakage and paper jamming due to influence on paper conveyance by blowing air onto the paper in the conveying path, can be prevented. At the start of paper conveyance, a gate 73 is turned upwards to a first position to thereby close a sixth conveying path 44 and establish communication between a first conveying path 42 and a second conveying path 43 so that the paper having passed through a fixing unit 21 starts to be conveyed from first conveying path 42 to second conveying path 43. At the same time, air is exhausted from an exhausting mechanism 53 arranged upstream of a cooling mechanism 76. When a first paper sensor 74 detects the leading end of the paper, a cooling fan 77 starts to rotate at a predetermined rotational rate to start blowing air at a predetermined volume of cooling airflow.

An image forming apparatus includes an image bearing member, a voltage source, a fixing device including a rotatable member, an executing portion for executing an operation in a both side mode, and a setting portion. The setting portion sets a transfer voltage in the operation for a second surface so that an absolute value of the transfer voltage when a recording material region, which starts from a most downstream end position and which passed through a fixing portion through a first one full circumference of the rotatable member when the toner image is fixed on a first surface passes through the transfer portion, is greater than an absolute value of the transfer voltage when a recording material region passed through the fixing portion through a second one full circumference of the rotatable member when the toner image is fixed on the first surface passes through the transfer portion.

The curl correction device includes a first guide that guides a sheet to a nip portion between a first rotation member and a second rotation member, a support portion that rotatably supports the first guide about a fulcrum on the downstream side of the first guide, and a restriction portion that restricts a rotation of the first guide rotating about the fulcrum by being in contact with the first guide. The first guide is rotatable about the fulcrum so as to become separated from the restriction portion.

An image forming apparatus includes an image printing unit configured to print an image on a sheet, a charge removing unit that is arranged downstream of a reversing conveyance path in a sheet conveyance direction and configured to remove a charge of a sheet, and a charge removing control unit configured to control voltage to be applied to the charge removing member, wherein the charge removing control unit performs control to apply voltage to the charge removing member with first polarity in a case where a first simplex printing operation is executed, to apply voltage to the charge removing member with second polarity in a case where a second simplex printing operation is executed, and to apply voltage to the charge removing member with the first polarity in a case where a duplex printing operation is executed.

An image forming system includes an image forming unit configured to form an image on a sheet, a reversing portion in which a front side and a back side of the sheet are to be reversed in order to form an image on a surface opposite to a surface of the sheet on which the image has been formed by the image forming unit, a duplex-printing conveying path for use in conveying the sheet having the front side and the back side reversed by the reversing portion to the image forming unit, a registration unit configured to correct a skew of the sheet conveyed to the duplex-printing conveying path, and an image reading sensor configured to read the image formed on the sheet having the skew corrected by the registration unit in the duplex-printing conveying path.