An image forming apparatus includes a control unit configured to perform a first mode, a second mode, and a third mode. The first mode is a mode in which a sheet conveyance unit is controlled so that an arrival time from a passage of a trailing edge of a preceding sheet through a nip portion to an arrival of a leading edge of a succeeding sheet succeeding to the preceding sheet at the nip portion becomes a first time. The second mode is a mode in which the sheet conveyance unit is controlled so that the arrival time becomes a second time. The third mode is a mode in which the sheet conveyance unit is controlled so that the arrival time becomes a third time. The second time is longer than the first time, and The third time is longer than the second time.

An image forming apparatus is provided with a sheet conveying device, a transfer device, a fixing device, a temperature sensor, a temperature control portion, and a conveyance control portion. The temperature control portion regulates power supplied to the heater by comparing between a temperature measured by the temperature sensor and a preset target temperature. The temperature control portion sets the target temperature to a first target temperature when an operation mode is a normal mode, and to a second target temperature lower than the first target temperature when the operation mode is a special mode. In a case in which the sequential printing process is performed, the conveyance control portion makes the sheet conveying device convey sheets at a longer interval when the operation mode is the special mode than when the operation mode is the normal mode.

An image forming apparatus includes an image bearing member; a transfer member; and a controller configured to execute a plurality of modes of outputting a test chart, the modes involving transferring a plurality of test images to the test chart by applying a plurality of different voltages to the transfer member. The modes include a first mode and a second mode, the first mode being a mode in which a number of voltage levels to be applied to the transfer member when the plurality of test images are transferred to the test chart is a first predetermined number, and the second mode being a mode in which the number of voltage levels to be applied to the transfer member when the plurality of test images are transferred to the test chart is a second predetermined number which is greater than the first predetermined number.

An image forming apparatus includes an image bearing member; a transfer member; and a controller configured to execute a plurality of modes of outputting a test chart, the modes involving transferring a plurality of test images to the test chart by applying a plurality of different voltages to the transfer member. The modes include a first mode and a second mode, the first mode being a mode in which a number of voltage levels to be applied to the transfer member when the plurality of test images are transferred to the test chart is a first predetermined number, and the second mode being a mode in which the number of voltage levels to be applied to the transfer member when the plurality of test images are transferred to the test chart is a second predetermined number which is greater than the first predetermined number.

A sheet discharging apparatus includes a sheet supporting portion supporting a sheet discharged out of a nip portion nipping the sheet and a guide portion provided opposed to an upper surface of the sheet fed out of the nip portion. The guide portion includes a fixed restricting portion restricting a rear end of the sheet with respect to a sheet discharging direction to moving upward away from an extension line in a sheet discharging direction of the nip portion after passing through the nip portion.

A sheet discharging apparatus includes a sheet supporting portion supporting a sheet discharged out of a nip portion nipping the sheet and a guide portion provided opposed to an upper surface of the sheet fed out of the nip portion. The guide portion includes a fixed restricting portion restricting a rear end of the sheet with respect to a sheet discharging direction to moving upward away from an extension line in a sheet discharging direction of the nip portion after passing through the nip portion.

A processor identifies an original drawing part that is originally drawn in a test image. Furthermore, the processor identifies a noise point in the test image. Furthermore, the processor determines which of predetermined two types of cause candidates is a cause of the noise point by determining a degree of overlapping between the original drawing part and the noise point. The two types of cause candidates are: waste toner dropping in which waste toner that has adhered to a transfer body that transfers a toner image to a sheet, is transferred to the sheet in the image forming device; and carrier developing in which magnetic carrier that has been mixed with toner is transferred to a sheet.

A processor identifies an original drawing part that is originally drawn in a test image. Furthermore, the processor identifies a noise point in the test image. Furthermore, the processor determines which of predetermined two types of cause candidates is a cause of the noise point by determining a degree of overlapping between the original drawing part and the noise point. The two types of cause candidates are: waste toner dropping in which waste toner that has adhered to a transfer body that transfers a toner image to a sheet, is transferred to the sheet in the image forming device; and carrier developing in which magnetic carrier that has been mixed with toner is transferred to a sheet.

An example of printing calibration includes printing a calibration page having test patches, the test patches developed at a plurality of voltages of a binary ink developer. The test patches are measured to determine an indication of ink thickness of the patches and a calibration voltage is generated based on the indications of the ink thickness of the test patches.

An example of printing calibration includes printing a calibration page having test patches, the test patches developed at a plurality of voltages of a binary ink developer. The test patches are measured to determine an indication of ink thickness of the patches and a calibration voltage is generated based on the indications of the ink thickness of the test patches.