An image forming unit of an image forming apparatus includes a developing device and a toner replenishing unit that replenishes the developing device with toner. The toner replenishing unit includes an upper toner container, a lower toner container, a toner conveyance unit. The upper toner container and the lower toner container are disposed in a staggered manner in an apparatus body.

A toner including toner base particles each including a binder resin and a colorant, and external additive, wherein the toner satisfies conditions (a), (b), and (c) below: (a) storage elastic modulus G(50) of the toner at 50 C. and storage elastic modulus G(90) of the toner at 90 C. satisfy Formula (1);

G(50)/G(90)6.010.sup.2Formula (1) (b) a BET specific surface area Bt(m.sup.2/g) of the toner and a coverage Ct (%) of the toner base particles covered with the external additive satisfy Formula (2); and

Bt0.03Ct1.60Formula (2) (c) the external additive includes at least cohered particles,
the cohered particles are non-spherical secondary particles each formed through cohesion of primary particles, and
a number average secondary particle diameter of the cohered particles is 130 nm or greater.

An image forming apparatus is provided that includes: first and second electrostatic latent image bearers; first and second electrostatic latent image forming devices; first and second developing devices configured to develop first and second electrostatic latent images with a colored toner and a special-color toner to form a colored toner image and a special-color toner image, respectively; a primary transfer device configured to transfer the colored toner image and the special-color toner image onto an intermediate image bearer in an overlapping manner to form a composite toner image; a secondary transfer device configured to transfer the composite toner image onto a recording medium; and a fixing device configured to fix the composite toner image thereon. The special-color toner comprises plate-like and/or film-like pigments. An absolute difference in volume resistivity between the special-color toner and the colored toner is 0.30 log cm or less.

In an image forming apparatus which includes a plurality of image forming units each including an image bearing member, a contact charging member, and a developer bearing member for forming toner of normal polarity, and which, in a printing operation, applies a charging bias having a first direction, in a cleaning operation, applies a charging bias having a second direction, and recovers residual toner remaining on the image bearing member which was not used for printing by the developer bearing member, before performing the cleaning operation, when successively performing the printing operation on a plurality of recording materials including a first recording material and a second recording material, which is used for printing following the first recording material, the charging voltage larger in absolute value in the printing operation for the second recording material than in the printing operation for the first recording material is applied.

An image forming unit of an image forming apparatus includes a developing device and a toner replenishing unit that replenishes the developing device with toner. The toner replenishing unit includes an upper toner container, a lower toner container, a toner conveyance unit, and a replenishment control unit. The upper toner container and the lower toner container are disposed in a staggered manner in an apparatus body. When the upper toner container becomes empty, the replenishment control unit controls the toner replenishing unit so as to replenish the developing device with the toner from the lower toner container.

An imaging device prints in color and monochromatically, such as black-only. It has a plurality of photoconductive drums, one each for black toner and at least one colored toner. The drums contact and rotate with an intermediate transfer member (ITM) to transfer images at a first transfer. During black-only imaging, the photoconductive drum for the black toner rotates with the ITM at process speed while the drum for the at least one colored toner rotates at less than process speed, often substantially less. The technique reduces consumption of colored toner during black-only imaging and minimizes charge build-up on the drum for the colored toner.

An image forming apparatus includes plural image forming units including plural image forming sections and an intermediate transfer body to which a toner image formed on the plural image forming sections is primarily transferred, and a processor, in which the processor is configured to, in a case where a printing instruction is received in a state in which an image forming section having a combination of identical colors is set for each of the plural image forming units, execute the printing instruction by using an image forming unit that is in a state in which image formation is able to be executed among the plural image forming units.

An image forming apparatus includes a first image forming section capable of forming a brilliant developer image, a second image forming section including at least one image forming section capable of forming a black developer image, a transfer section capable of transferring the brilliant developer image and the black developer image onto a medium, and a controller that controls operation of the first image forming section and the second image forming section according to received print data. When forming a brilliant image based on the print data, the controller performs control to form the brilliant image in which relative position between the brilliant developer image and the black developer image is changed depending on a medium type.

An image forming apparatus includes a latent image bearer, an electrostatic latent image forming device, a potential sensor, a toner image forming device, a toner adhesion amount detector, and circuitry. The circuitry controls the electrostatic latent image forming device to create an adjustment pattern on the latent image bearer when the image forming apparatus is not printing, controls the potential sensor to detect an electric potential of the adjustment pattern, controls the electrostatic latent image forming device and the toner image forming device to create a test toner image during a printing period, controls the toner adhesion amount detector to detect a toner adhesion amount of the test toner image, and adjusts at least one image forming condition of the electrostatic latent image forming device and the toner image forming device based on the electric potential of the adjustment pattern and the toner adhesion amount of the test toner image.

An image forming apparatus includes an image forming unit that has multiple developing units, arranged in series for basic colors in a rotational driving direction of a transfer body, for developing toner images of the basic colors based on input image data and forms the overlapped toner images on a surface of the transfer body in a state in which the toner images are aligned; a transferring unit that transfers the toner images onto a sheet; and a controller that calculates a difference between color information of an image obtained by reading the toner images and color information of the input image data, calculates a color change direction of the toner images with respect to a color of the input image data based on the difference, and refers to a table and determines a shape of a surface of the sheet based on information of the color change direction.