According to one embodiment, an image forming apparatus includes a sheet supply unit, a printer, a fixing device, and a controller. The sheet supply unit supplies a sheet from a sheet container. The printer forms a toner image to the sheet conveyed from the sheet supply unit. The fixing device includes a heater, a fixing belt, and a pressure roller. The heater includes a heat generating member including a plurality of heating elements arranged in a first direction orthogonal to a sheet conveyance direction and in which a heating element group selected in response to a printing request from the heat generating member generates heat. The fixing belt fixes the toner image heated by the heater to the sheet. The pressure roller presses the fixing belt.

A heating device (9) includes a heater (22), a holder (23), a device frame (40), a primary positioner (A), a secondary positioner (B), and a tertiary positioner (C). The heater includes a heat generator (60). The holder holds the heater. The device frame is configured to support the holder. The primary positioner is configured to position the heater and the holder in a longitudinal direction of the heater. The secondary positioner is configured to position the holder and the device frame in the longitudinal direction of the heater. The tertiary positioner is configured to position the device frame and a body of an image forming apparatus in the longitudinal direction of the heater. The primary positioner and one of the secondary positioner and the tertiary positioner are disposed on an identical side defined by a center of the heat generator in the longitudinal direction of the heater.

An image forming apparatus includes an image forming portion configured to form a developer image on a recording material, a fixing portion configured to heat-fix the developer image to the recording material, a first motor configured to drive the image forming portion, a second motor configured to drive the fixing portion, and a control portion configured to control the first motor and the second motor. The second motor is a stepping motor. The control portion allows the second motor to start rotation at a speed in a self-start region, temporarily stops the second motor at a timing at which the first motor is activated, then allows the second motor to restart rotation at a speed in the self-start region, and changes the speed of the second motor to a speed outside the self-start region before the recording material arrives at the fixing portion.

A fixing device includes: a fixing belt of an endless shape wound to pass over a heating-side member and a nip forming member; and a pressing roller driven to rotate in a state of being brought into tight contact with the nip forming member through the fixing belt, wherein a toner image is fixed to a recording medium at a nip portion at which the fixing belt and the pressing roller are brought into tight contact with each other by causing the pressing roller to be in tight contact with the fixing belt and driving the pressing roller to rotate, a guide member guiding the fixing belt to a space between the nip forming member and the heating-side member is disposed to be separate from the nip forming member, and a sliding member is disposed at least in a contact portion between the nip forming member and the fixing belt.

A heating device includes a heater, a holder, a device frame, a primary positioner, a secondary positioner, and a tertiary positioner. The heater includes a heat generator. The holder holds the heater. The device frame is configured to support the holder. The primary positioner is configured to position the heater and the holder in a longitudinal direction of the heater. The secondary positioner is configured to position the holder and the device frame in the longitudinal direction of the heater. The tertiary positioner is configured to position the device frame and a body of an image forming apparatus in the longitudinal direction of the heater. The primary positioner and one of the secondary positioner and the tertiary positioner are disposed on an identical side defined by a center of the heat generator in the longitudinal direction of the heater.

In a caser where a first current is supplied to a first heater, a controller gradually increases the first current in a first period, supplies the first current based on a first duty cycle in a second period, and gradually reduces the first current to stop supplying the first current in a third period. In a case where a second current is supplied to a second heater, the controller gradually increases the second current in a fourth period, supply the second current based on a second duty cycle in a fifth period, and gradually reduces the second current to stop supplying the second current in a sixth period. The controller controls the supply of the second current such that part of the fourth period overlaps with the third period.

An image forming apparatus is disclosed. A fixing device includes a heating rotary member and a pressing rotary member. The fixing device further includes an acquisition means that acquires information about a printing medium for a predetermined number of sheets beforehand, and a temperature control means that controls a temperature of the heating rotary member based on the information about a basis weight acquired by the acquisition means. A job in which different basis weights are mixed is a mixed job. In a case where the mixed job is executed and the temperature of the heating rotary member is changed while the mixed job is executed, a change amount of the temperature of the heating rotary member is reduced based on the information about the basis weight of the printing medium acquired by the acquisition means.

A fixing device includes a fixing belt, a nip formation pad, a support, an opposing rotator, a heat source, a housing, an inlet guide, an airflow generator, and an airflow guide. The fixing belt fixes an unfixed image on a recording medium. The nip formation pad is disposed inside a loop of the fixing belt. The support supports the nip formation pad. The opposing rotator abuts on the nip formation pad via the fixing belt. The heat source heats the fixing belt. The housing has an inlet opening to receive the recording medium. The inlet guide is disposed at the inlet opening and guides the recording medium to the fixing nip. The airflow generator generates an airflow in the housing. The airflow guide guides the airflow toward the inlet opening to generate a flow of air in the inlet opening in a direction different from a conveyance direction.

A fixing device includes a movable belt; and a planar heat-generating section that is in contact with the belt and in which, among plural heat-generating portions provided in a movement direction of the belt, a heat-generating portion on an upstream side in the movement direction of the belt has a larger heat generation amount than a heat-generating portion on a downstream side.

An image forming apparatus includes a fixing belt, a steering roller, a pressure rotation member, and a control unit. The pressure rotation member forms a nip portion with the fixing belt to convey a recording material. In continuously performing fixing on recording materials, the control unit controls the steering roller such that a distance between a center position of the fixing belt when an operation to tilt the steering roller is performed for a first time after the center position is moved away from a center position of a moving range of the fixing belt and the center position of the moving range is smaller in a period after a last but one recording material before the pressure rotation member enters a separated state from the fixing belt passes through the nip portion than in a period before the recording material passes through the nip portion.