According to one embodiment, an image forming apparatus includes: an image forming unit configured to form a toner image using a first toner supplied to the image forming unit with a first process bias VR; a density sensor configured to detect a density of toner in the image forming unit; a toner cartridge containing a second toner and including a memory that stores data representing a process bias VA appropriate for the second toner; a mounting unit on which the toner cartridge is mounted; and a toner replenishing unit configured to replenish the image forming unit with the second toner from the toner cartridge mounted on the mounting unit based on the density, in which a density detected by the density sensor when the toner cartridge is mounted on the mounting unit is converted into an estimated amount, and the image forming unit is set to a process bias V until the image forming unit is replenished with the second toner by the estimated amount after the toner cartridge is mounted on the mounting unit, the process bias V being obtained from the following formula V=VA−((VA−VR)/the estimated amount)×(an amount of the second toner with which the image forming unit is replenished after the toner cartridge is mounted on the mounting unit).

An image forming apparatus includes an image carrier, an exposure device, a developer image forming unit, a memory, and a processor. The image carrier carries a developer image. The exposure device exposes the image carrier. The developer image forming unit forms the developer image by transporting a developer to a latent image formed on the image carrier. The processor generates correction data for correcting density unevenness in a main scanning direction detected based on an image generated by the developer image, corrects the density unevenness in the main scanning direction occurring in the developer image by changing an exposure amount when the image carrier is exposed by the exposure device, using the generated correction data, and when a position change of the developer image forming unit in the main scanning direction is detected, adjusts the correction data by a detected position change amount.

An apparatus includes a combination unit configured to, in a case where print is print on a second sheet of paper out of two sheets of paper into which mark information for gradation adjustment is divided on a two colors-by-two colors basis, and a type of paper of the second sheet of paper is the same as a type of paper of a first sheet of paper, and in a case where a chart insertion job is not requested or the print is based on the chart insertion job, combine the mark information for gradation adjustment for remaining two colors or four colors with a print image in accordance with a size of the second sheet of paper.

An image forming apparatus for forming an image on a recording material. The image forming apparatus includes an image forming portion, a fixing portion, an oblique movement detecting portion, and a controller. The image forming portion is configured to form the image on the recording material. The fixing portion includes a flexible cylindrical rotatable member and a roller in press contact with the rotatable member. The rotatable member and the roller are configured to form a fixing nip, in which the recording material, on which the image is formed, is nipped and fed. The oblique movement detecting portion is configured to detect oblique movement of the recording material. When the oblique movement detecting portion detects the oblique movement of the recording material, the controller increases a feeding interval of the recording material to the image forming portion.

An image forming apparatus includes a controller configured to control a first image forming unit such that while a plurality of images are being sequentially formed, a first pattern image is formed in a first sheet-to-sheet area between a first black image and a second black image among the plurality of images on a first photosensitive body, and control the second image forming unit such that while the plurality of images is being sequentially formed, a second pattern image are formed in a second sheet-to-sheet area between a first color image and a second color image among the plurality of images on a second photosensitive body. The first sheet-to-sheet area in a case where the first pattern image is formed without the second pattern image being formed is narrower than the first sheet-to-sheet area in a case where the first pattern image and the second pattern image are formed.

An image forming apparatus includes a paper transport unit, an image forming unit, a reading unit, a foreign matter detection signal generation circuit, and a foreign matter detection control circuit. The foreign matter detection signal generation circuit generates a first foreign matter detection signal, based on an analog image signal to be output from a line sensor. In foreign matter detection processing, when a pixel that reads foreign matter continues by a specific first consecutive number or more in a signal based on the analog image signal of each pixel to be output from the line sensor, the foreign matter detection signal generation circuit sets a level of the first foreign matter detection signal to a level indicating the presence of foreign matter.

An image forming device to and from which a developing unit in which a developer containing toner is filled is detachable and removable, comprises a hardware processor that: enables the developing unit to perform a stir operation of the developer filled in the developing unit as an initial operation of the developing unit; obtains a reference value of a toner density set in advance in time of a factory shipment of the developing unit at time the stir operation is performed; and compares a toner density received from the developing unit during the stir operation with the reference value to determine a stir condition of the developer.

An image forming apparatus includes a developer container, an agitator, a toner supply, a toner sensor, and a controller. The developer container contains a two-component developer that includes toner and carrier. The agitator stirs the two-component developer. The toner supply replenishes the developer container with additional toner. The toner sensor detects a toner density of the two-component developer in the developer container. The controller calibrates the toner sensor using the two-component developer. The controller compares a first detection value indicating a toner density at a first time with a second detection value indicating a toner density at a second time after a predetermined time period has elapsed since the first time. The controller issues a notification regarding a suitability of calibration based on a comparison result of the first detection value and the second detection value.

An image forming apparatus includes an image forming device configured to form an image on a sheet using a rotating body under a predetermined image forming condition, a corrector configured to determine a correction amount for the image forming condition to adjust image density unevenness corresponding to a rotation cycle of the rotating body, and a controller configured to control the image forming device to form, on a single sheet, plural test images that are different in the correction amount.

An image forming apparatus includes: a photoconductor; a transfer portion; a photoconductor cleaner that removes residual toner from a surface of the photoconductor; and a first processor that forms a toner patch on the surface of the photoconductor. When the toner patch passes the transfer portion, the transfer portion makes the toner patch stay on the surface of the photoconductor such that toner of the toner patch is able to be supplied to the photoconductor cleaner. The first processor further determines an amount of toner for the toner patch with reference to a circumferential distance the photoconductor travels for a predetermined period of time.