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 electrostatic charge image developing toner contains toner particles that contain an organic colorant and a binder resin, in which the organic colorant includes a non-fluorescent organic pigment and a fluorescent organic pigment, a total content of the organic colorant is 5% by mass or more and 20% by mass or less with respect to a total mass of the toner particles, and a specific gravity D1 of the non-fluorescent organic pigment and a specific gravity D2 of the fluorescent organic pigment satisfy both of Formulas (1) and (2).

D1≥2.0  Formula (1)

D1−D2≥0.6  Formula (2).

An image forming apparatus includes an image forming device and circuitry. The image forming device forms an image with colorants of different colors. The circuitry determines whether there is a possibility that a shortage of a colorant adhesion amount occurs in primary-color image formation using a colorant of a primary color and cause the image forming device to perform two-color image formation in which only secondary-color image formation using a colorant of a secondary color different from the colorant of the primary color is added to the primary-color image formation using the colorant of the primary color to form an image to be formed with the colorant of the primary color, when the circuitry determines that there is a possibility that the shortage of the colorant adhesion amount occurs in the primary-color image formation using the colorant of the primary color.

An image forming apparatus includes an image forming device and circuitry. The image forming device forms an image with colorants of different colors. The circuitry determines whether there is a possibility that a shortage of a colorant adhesion amount occurs in primary-color image formation using a colorant of a primary color and cause the image forming device to perform two-color image formation in which only secondary-color image formation using a colorant of a secondary color different from the colorant of the primary color is added to the primary-color image formation using the colorant of the primary color to form an image to be formed with the colorant of the primary color, when the circuitry determines that there is a possibility that the shortage of the colorant adhesion amount occurs in the primary-color image formation using the colorant of the primary color.

A developing device including a developing sleeve installed in a developing chamber and partially exposed to an outside of the developing chamber through an opening portion, a magnetic member located inside a developing sleeve and including a separating pole and a receiving pole, the separating pole being located on a downstream side of the opening portion based on a rotating direction of the developing sleeve to separate a developing agent from the developing sleeve, and the receiving pole being located on a downstream side of the separating pole to attach the developing agent to the developing sleeve, and a magnet located between an inner wall of the developing chamber and the magnetic member to face a region between the separating pole and the receiving pole and having same magnetic polarity same as the separating pole and the receiving pole.

In an image forming apparatus, a first photosensitive drum is disposed upstream of a second photosensitive drum in a conveyance direction. Each of first and second developing rollers is movable between a contact position contacting a corresponding photosensitive drum and a separated position separated from the corresponding photosensitive drum. In a first case where a color print process is executed, a first moving mechanism starts moving the first developing roller toward the contact position, a manual feed roller starts picking up the sheet on a manual feed tray, and a second moving mechanism starts moving the second developing roller toward the contact position. In a second case where the monochrome print process is executed, the manual feed roller starts picking up the sheet on the manual feed tray, and the second moving mechanism starts moving the second developing roller toward the contact position.

A developing device including a developing sleeve installed in a developing chamber and partially exposed to an outside of the developing chamber through an opening portion, a magnetic member located inside a developing sleeve and including a separating pole and a receiving pole, the separating pole being located on a downstream side of the opening portion based on a rotating direction of the developing sleeve to separate a developing agent from the developing sleeve, and the receiving pole being located on a downstream side of the separating pole to attach the developing agent to the developing sleeve, and a magnet located between an inner wall of the developing chamber and the magnetic member to face a region between the separating pole and the receiving pole and having same magnetic polarity same as the separating pole and the receiving pole.

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 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 plural image forming units and a controller. The plural image forming units are configured to form images of colors using colorants, respectively. The controller is configured to perform control such that the plural images formed by the plural image forming units are output as one image onto a recording medium. At least two of the image forming units are configured to form images using colorants of special colors, respectively and are arranged in succession.