An image forming apparatus includes: a rotatable transfer cylinder with a first groove formed in an outer portion thereof in a rotational radial direction that causes an image to be transferred to a recording medium when it passes along an outer surface of the transfer cylinder; a rotatable fixing cylinder that has a second groove formed in an outer portion thereof in a rotational radial direction, that causes the image transferred to the recording medium to be fixed thereto when the recording medium passes along an outer surface of the fixing cylinder; a loop-shaped circulating member that is wrapped at least around the transfer and fixing cylinders, that circulates in response to rotations of the transfer and fixing cylinders; a recording medium holding member supported by the circulating member, disposed in the first groove when the holding member passes along the transfer cylinder and disposed in the second groove when the holding member passes along the fixing cylinder; first and second driving units that rotate the transfer and fixing cylinders respectively; and that is configured such that a ratio of a moment of inertia of the fixing cylinder to an output torque of the second driving unit is set to be greater than a ratio of a moment of inertia of the transfer cylinder to an output torque of the first driving unit.

An image forming apparatus includes an image forming unit, a fixing unit, a heating portion and a removal unit to remove a particulate dust generated due to vaporization of a parting agent by heat in the fixing unit. The removal unit includes a sheet-like filter provided with a base layer and a collecting layer laminated on the base layer for collecting dust. The removal unit includes a holding unit to hold the filter in a cylindrical shape with the base layer outside and the collecting layer inside. The removal unit includes a fan connected to one of opening end sides of the filter held in the cylindrical shape and generates an air flow inside of the cylindrical shape which causes air passing from outside of the filter to inside to flow toward the one of the opening end sides.

An example image forming apparatus includes an endless belt to rotate, belt rollers including a tension roller and an adjustment roller extending inside the endless belt, a nip roller extending adjacent the endless belt to form a nip between the nip roller and the endless belt, and a cam shaft that includes a nip forming cam and a tension adjustment cam. The nip forming cam moves the nip roller between a pressed position in which the nip roller is pressed against the endless belt, and a retracted position in which the nip roller is retracted from the endless belt. The tension adjustment cam moves the adjustment roller relative to the tension roller.

A heating apparatus includes a cylindrical film and a pressing element that rotates with the cylindrical film and forms a nip with the cylindrical film. A medium is conveyed through the nip from an upstream side to a downstream side. The heating apparatus further includes a heater arranged inside the cylindrical film and on which a heating element is disposed. An upstream end of the heater is located downstream of an upstream end of the nip, and a downstream end of the heater is located downstream of a downstream end of the nip.

An image forming apparatus for forming a toner image on a recording material includes a fixing unit and a blower unit to blow air around a roller. The fixing unit includes a tubular shape film, a heating member disposed in a space surrounded by the film, and the roller forming a nip portion with the heating member. The fixing unit heats and fixes the toner image onto the recording material at the nip portion. For printing that forms toner images on continuously conveyed recording materials where a roller surface temperature is lower than a predetermined temperature, fan stop and operation periods are set. During the fan stop period, the blower unit is stopped and an interval between preceding and subsequent recording materials is widened. During the fan operation period, the blower unit is in operation and the interval is narrower than the interval during the fan stop period.

An image forming apparatus includes a single fan, a first air outlet port disposed so as to supply air sent from the fan to an image surface of the sheet, a second air outlet port disposed so as to supply the air sent from the fan to a surface opposite to the image surface of the sheet, and a control unit configured to control the fan. The control unit includes a first mode of controlling a rotational speed of the fan at a first rotational speed in a case where the sheet is not present in a position facing the first air outlet port and control the rotational speed of the fan at a second rotational speed lower than the first rotational speed in a case where the sheet is present in the position facing the first air outlet port.

An image forming apparatus includes an endless belt to rotate, belt rollers including a tension roller and an adjustment roller extending inside the endless belt, a nip roller extending adjacent the endless belt to form a nip between the nip roller and the endless belt, and a cam shaft that includes a nip forming cam and a tension adjustment cam. The nip forming cam moves the nip roller between a pressed position in which the nip roller is pressed against the endless belt, and a retracted position in which the nip roller is retracted from the endless belt. The tension adjustment cam moves the adjustment roller relative to the tension roller.

An image forming apparatus includes a fixing device and a drive transmission mechanism. The fixing device fixes an image on a sheet by application of heat and pressure. The drive transmission mechanism changes a conveying speed of the sheet in the fixing device between an image forming mode and a lamination mode. The conveying speed of the sheet in the fixing device in the lamination mode is lower than the conveying speed of the sheet in the fixing device in the image forming mode.

A heat roller includes a main body and a follower gear. The main body includes a cutaway portion and a pair of protruding plate portions. The follower gear includes a transmission protrusion and an abutment portion. The transmission protrusion is abutted against one protruding plate portion, when the follower gear rotates. The abutment portion is abutted against the one protruding plate portion, when the main body rotates in advance. A size of the transmission protrusion along the width direction of the cutaway portion is smaller than a clearance between the pair of protruding plate portions in the width direction, and a clearance between the abutment portion and the one protruding plate portion in the roller rotation direction is narrower than a clearance between the transmission protrusion and the other protruding plate portion in the roller rotation direction, when the transmission protrusion is in contact with the one protruding plate portion.

In an image forming apparatus, a controller causes a first fixing member to heat up to a standby temperature Tr lower than a fixing temperature, through a control process executed from a state in which rotation of the first fixing member is stopped and a nip pressure is set at a second pressure smaller than a first pressure. The control process includes: a first process of activating and controlling a heater to cause the first fixing member to heat up toward a target temperature; a second process of starting the rotation of the first fixing member; a third process of changing the nip pressure from the second pressure to the first pressure; a fourth process of changing the nip pressure from the first pressure to the second pressure; and a fifth process of stopping the rotation of the first fixing member, executed in this sequence.