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.

An image forming apparatus includes: an image holding section; a transfer section that includes a transfer member, applies a transfer electric-field to a transfer region between the image holding section and the transfer member, and electrostatically transfers an image held by the image holding section onto a recording medium; a contact section that acts as an electrode to ground while being in contact with the recording medium when the recording medium passes through the transfer region; a first resistance detection section; a second resistance detection section; a comparison section that compares a first system resistance detected by the first resistance detection section with a second system resistance detected by the second resistance detection section; and a switching section that switches between constant voltage control and constant current control for the transfer electric-field produced by the transfer section depending on a result of comparison by the comparison section.

An image forming apparatus that is capable of preventing discharged sheet adhesion while lowering degradation of productivity. A print unit prints an image on a sheet based on a print job. A fixing unit fixes the image primed on the sheet to the sheet. The sheet to which the image is fixed is discharged to a discharge tray. A counter counts discharged sheet number that is the number of sheets discharged to the discharge tray during a continuous print operation. A controller controls the print unit so as to lower productivity that is discharging sheet number per unit time in response to increase in the discharged sheet number counted by the counter and so as to recover the productivity in a case where the sheets discharged to the discharge tray are removed in a state where the productivity is lowered.

An image forming apparatus includes a black image forming portion, a color image forming portion, an intermediary transfer member, a transfer portion, and an executing portion capable of executing an operation in a color mode in which a color image is formed using the color image forming portion and the black image forming portion and an operation in a monochromatic mode in which a monochromatic image is formed using only the black image forming portion. The executing portion is capable of forming the monochromatic image in the operation in the monochromatic mode under application of a voltage to the black developing device. The voltage is applied under a voltage condition such that a line width is broader than a line width under a voltage condition inputted to the black developing device when the operation in the color mode is executed.

An image forming apparatus includes a toner image supporting section and a medium transfer section. The toner image supporting section includes first and second toner image supporting member that support first and second toner images at first and second linear speeds, respectively. The medium transfer section transfers, onto a medium, the first and second toner images respectively supported by the first and second toner image supporting members, to thereby cause the first and second toner images to be superimposed on each other. The following conditional expression (1) is satisfied when the medium transfer section transfers the first and second toner images onto the medium,
(Vd1Vt1)/(Vt1>(Vd2Vt2)/Vt2(1)
where Vd1 is the first linear speed, Vt1 is a first conveyance speed of the medium, Vd2 is the second linear speed, and Vt2 is a second conveyance speed of the medium.

According to one embodiment, an image forming apparatus of the embodiment includes a roller, a plurality of developing units, an image forming unit, a sensor, and a control unit. The rollers carry a sheet. The plurality of developing units include different types of developing materials. The image forming unit forms a plurality of images on a transfer belt by the developing materials of each of the plurality of developing units. The sensor reads the plurality of images formed on the transfer belt. The control unit controls the speed of the roller based on the positions of the plurality of images read by the sensor.

An image forming apparatus includes an image forming unit to form an image on a sheet based on a mode selected from a plurality of modes having different image forming speeds, a memory to store first data for a first mode included in the plurality of modes, the first data indicating a correspondence for the first mode between a type of the sheet and the image forming speed, and second data for a second mode included in the plurality of modes, the second data indicating a correspondence for the second mode between a type of the sheet and the image forming speed, and a display. A controller determines a first image forming speed for the first mode from the first data based on the type of the sheet, and determines a second image forming speed for the second mode from the second data.

An image forming apparatus includes an image forming portion, a reverse roller pair, a revering motor. A controller controls rotation of the reverse motor in a first feeding mode for the sheet with a first length and in a second feeding mode for the sheet with a second length longer shorter than the first length. The controller executes a first acceleration control in which the reverse motor rotating in the first rotational direction is accelerated from a predetermined speed to a first target speed faster than the predetermined speed after a rear end of the sheet passes through the image forming portion in the first feeding mode, and said controller executes a second acceleration control in which the reverse motor rotating in the first rotational direction is accelerated to a second target speed slower than the first target speed after the rear end of the sheet passes through the image forming portion in the second feeding mode.

An image forming apparatus that is capable of properly grasping a load that is imposed on the image forming apparatus by performing high-chroma printing. The image forming apparatus includes a printer engine that causes a heating rotary body to support and convey a sheet with a toner image formed thereon and performs an image formation on the sheet. The printer engine is controlled to perform the image formation on sheets in a first mode in which a toner image based on a piece of image data is formed with a first amount of toner, or a second mode in which a toner image based on the piece of image data is formed with a second amount of toner larger than the first amount of toner. A count function for counting the number of times of the image formation performed in the second mode, rather than the first mode, is performed.

An image forming apparatus includes an image forming portion configured to form a toner image on a recording material, a fixing portion configured to heat and to fix the toner image formed on the recording material, and a controller configured to control the apparatus, which is operable to form an image on a recording material having a first size and a recording material having a second size smaller than the first size in a direction perpendicular to a recording material feeding direction. If a printing instruction for printing on the recording material of the first size is received while continuously printing on the recording material of the second size at a first throughput, the controller controls the apparatus so as to print on the recording material of the second size at a second throughput, lower than the first throughput, before printing on the recording material of the first size.