An image forming apparatus includes a conveyance unit, an irradiation unit, an image capturing unit configured to capture a plurality of times the light radiated by the irradiation unit and reflected on the recording material as surface images, an image formation unit, and a control unit, wherein the conveyance unit accelerates or decelerates a conveyance speed of the recording material in at least a part of an image capturing period during which the image capturing unit captures the surface images the plurality of times, and wherein the control unit obtains a feature quantity from a plurality of surface images captured by the image capturing unit and controls the image forming condition based on the obtained feature quantity and a threshold value set according to the conveyance speed of the recording material in the image capturing period.

A fixing device according to an embodiment includes an endless belt, a pressure element, a heating member, an adjustment mechanism, and a controller. The pressure element conveys and presses a sheet to the endless belt. The heating member is on the inner side of the belt and has a heat generating element for heating the belt. The adjustment mechanism moves the heating member or the pressure element to adjust the nip width between the heating member and the pressure element. The controller controls the adjustment mechanism so that A>B≥N is satisfied, where A is the nip width during a fixing process in which a colored material is fixed to the sheet, B is the nip width during a heating process conducted before the fixing process, and N is the length of the heat generating element in the sheet conveyance direction.

An image forming apparatus includes a control unit configured to, in executing a job to form images continuously on a plurality of sheets of a recording material, accumulate an addition amount per sheet to an index in accordance with a number of sheets of the recording material to which images are formed in the job. A value of the addition amount per sheet is determined in correspondence with an attribute of the recording material used in the job. The control unit is configured to, during execution of the job, change a throughput of the job so that images are formed at a first throughput if an accumulated value of the index still does not exceed a predetermined threshold value and images are formed at a second throughput slower than the first throughput if the accumulated value of the index has exceeded the threshold value.

An image forming apparatus, including: a control portion that controls a conveying speed of recording materials when the recording materials pass through a nip portion; wherein the control portion, in a case of continuous sheet passing of the recording materials each having a smaller width than the recording materials each having a maximum width: executes, in a case where a representative value of the number of the recording materials having the smaller width for one operation of the continuous sheet passing is smaller than a predetermined threshold, a first operating mode in which the conveying speed is controlled to a first speed; and executes, in a case where the representative value is the threshold or more, a second operating mode in which the conveying speed is controlled to a second speed lower than the first speed.

A fixing device is provided with a first rotating member, a second rotating member in contact with the first rotating member, a first drive motor for rotationally driving the first rotating member, a second drive motor for rotationally driving the second rotating member, a torque limiter provided between the second rotating member and the second drive motor, and a pressure adjusting mechanism for adjusting the nip pressure between the first rotating member and the second rotating member. When the nip pressure is greater than the maximum torque that can be transmitted by driving the torque limiter, the second rotating member rotates following the first rotating member and at the same linear speed as that of the first rotating member, and when the nip pressure is equal to or less than the maximum torque, the second rotating member rotates at a linear speed different from that of the first rotating member.

A fixing device is provided with a first rotating member, a second rotating member in contact with the first rotating member, a first drive motor for rotationally driving the first rotating member, a second drive motor for rotationally driving the second rotating member, a torque limiter provided between the second rotating member and the second drive motor, and a pressure adjusting mechanism for adjusting the nip pressure between the first rotating member and the second rotating member. When the nip pressure is greater than the maximum torque that can be transmitted by driving the torque limiter, the second rotating member rotates following the first rotating member and at the same linear speed as that of the first rotating member, and when the nip pressure is equal to or less than the maximum torque, the second rotating member rotates at a linear speed different from that of the first rotating member.

An image forming apparatus includes a fixing device and a controller. The fixing device includes a heating unit and a pressurizing unit. The heating unit is configured to come into contact with a recording medium, onto which an image is transferred and which is transported, so as to heat the recording medium while rotating. The pressurizing unit is configured to press the recording medium against the heating unit. The fixing device is configured to fix the image to the recording medium. The controller is configured to control switching between a first mode for fixing the image to the recording medium and a second mode for making a transport speed of a sheet member that passes through the fixing device slower than a peripheral speed of the heating unit.

An image forming apparatus includes a motor, an image formation-transfer section, a switching mechanism, a fixing section, and a controller. The motor generates driving force. The image formation-transfer section state-changes between a first contact state and a first separate state by the driving force. The switching mechanism transmits and cuts off the driving force to the image formation-transfer section. The fixing section includes first and second rotating members, and state-changes between a second contact state and a second separate state by the driving force. The controller controls the motor and the switching mechanism and thereby causes part or all of a first period, in which the fixing section state-changes from the second separate state to the second contact state, and part or all of a second period, in which the image formation-transfer section state-changes from the first separate state to the first contact state, to overlap each other.

A controller is configured to control a drive unit and a heating element to execute a first mode and a second mode. The first mode is a mode in which the sheet is conveyed through a predetermined conveyance section in a duplex image formation by taking a first time length. The second mode is a mode in which the sheet is conveyed through the conveyance section in the duplex image formation by taking a second time length longer than the first time length. In the second mode, the controller is configured to execute a temperature decrease processing and thereafter execute a temperature increase processing in a period in which the sheet is conveyed through the conveyance section.

A fixing device includes a rotatable fixing belt, a pad, a rotatable pressing member, a pressing member driving source, an auxiliary driving roller, and a transmission mechanism for transmitting a driving force from the pressing member during source to the auxiliary driving roller, wherein a peripheral speed of the auxiliary driving roller is faster than a peripheral speed of the pressing member, and a steering roller provided so as to stretch the fixing belt at the inner surface of the fixing belt in a position downstream of the auxiliary driving roller and upstream the pad with respect to a rotational direction of the fixing belt. The steering roller adjusts a position of the fixing belt with respect to a widthwise direction of the fixing belt by inclining the fixing belt so as to be positioned within a predetermined range.