A control portion causes an image forming portion to execute a test output process in which a plurality of test toner images each having a different developing voltage condition are formed in sequence on a surface of each of a plurality of image-carrying members and then transferred to an intermediate transfer body. The control portion sequentially selects, from the plurality of image-carrying members, target image-carrying members that are arranged at a distance greater than an arrangement spacing of the plurality of image-carrying members, and causes the image forming portion to execute the test output process so that each time one of the plurality of target image-carrying members is selected, the plurality of test toner images for each of the plurality of target image-carrying members are transferred within an area on the surface of the intermediate transfer body whose length corresponds to pacing between the plurality of target image-carrying members.

An image forming apparatus includes an image forming section, an optical scanning device, an image density sensor, and a control unit. The optical scanning device scans the surface of the image carrying member with light emitted from light sources to form an electrostatic latent image. The control unit can perform light amount calibration to adjust the exposure amount of the light scanning device based on the density of a reference image detected by the image density sensor. The reference image used for light amount calibration has a dot pattern in which as many individual dots as there are light sources are arrayed at regular intervals in the main scanning direction. The dot pattern is formed repeatedly in the main and sub scanning directions. The dots forming the dot pattern are arranged at different positions in the sub scanning direction to be displaced in units of pixels from each other.

An image forming apparatus includes an image forming portion, a first image processing portion, and a second image processing portion. The second image processing portion, when a predetermined execution condition is satisfied, executes a detection image forming process in which a detection image that is used for adjusting an image forming condition in the image forming portion, is formed by the image forming portion in an area outside a print area on a transfer object. In a case where, after the detection image forming process is started during execution of a normal image forming process, the normal image forming process ends before the detection image forming process ends, the second image processing portion switches between continuing and not continuing the detection image forming process in accordance with a predetermined switch condition.

An image forming apparatus includes an image forming portion, a first image processing portion, and a second image processing portion. The first image processing portion executes a plurality of types of image formation condition adjustment processes of the image forming portions on the image forming units used for monochrome printing in units of a specific number of condition adjustment processes in order whenever an execution history of the monochrome printing satisfies a monochrome adjustment condition set in advance. The plurality of types of condition adjustment processes is set in advance. The second image processing portion executes the plurality of types of condition adjustment processes on the image forming unit of the plurality of image forming units used for color printing in units of a specific number of condition adjustment processes in order whenever an execution history of the color printing satisfies a color adjustment condition set in advance.

According to an embodiment, an image forming apparatus executes, if an execution frequency setting of positional deviation correction in setting information is equal to or larger than a reference value, the positional deviation correction by using an image pattern for positional deviation measurement that is formed to be equal to or larger than one cycle of a transfer belt. Further, the image forming apparatus executes, if the execution frequency setting of the positional deviation correction in the setting information is less than the reference value, the positional deviation correction by using an image pattern for positional deviation measurement that is formed to be smaller than one cycle of the transfer belt.

An image forming apparatus including: an image bearer; an image formation unit forming toner image on the image bearer according to image formation conditions; a transfer unit including a transfer member, transferring the toner image on the image bearer to recording medium at a transfer nip between the image bearer and the transfer member; a toner adhesion amount detection unit detecting a toner adhesion amount of a toner pattern transferred from the image bearer to the transfer member; an image formation condition adjustment unit adjusting the image formation condition, based on a detection result of the toner adhesion amount detection unit; a transfer pressure setting change unit changing a transfer pressure setting of the transfer nip; and a correction unit correcting an adjustment value of the image formation condition adjustment unit, based on a correction value corresponding to a changed transfer pressure setting by the transfer pressure setting change unit.

An image forming device includes: a photoreceptor drum; a developer that forms a toner image on the photoreceptor drum; a development-power supplier that supplies the developer with a developing bias; an image sensor that detects a density of a toner image; an environment sensor that detects a temperature and humidity; a replenisher that replenishes the developer with toner; and a controller that causes image-quality adjustment that changes the developing bias to be performed. The controller includes a storage that holds a replenishment condition in which timing at which the replenisher replenishes the toner is set, a correction value for the replenishment condition, and an ideal bias, and the controller corrects a correction value used until the next image-quality adjustment based on a bias difference that is a difference between an adjustment bias and the ideal bias, and a last correction value set in the last image-quality adjustment.

An image forming apparatus includes processing circuitry and a sensor. The processing circuitry controls formation of an image of an evaluation pattern on a transfer object. The sensor measures the image of the evaluation pattern formed on the transfer object. The processing circuitry presents a determination result of a cause of a failure based on a comparison between a reference value serving as a reference of the evaluation pattern and a measured value of the image of the evaluation pattern by the sensor.

An image forming apparatus includes an image former, a detector, and circuitry. The image former forms a toner pattern with a first line screen; and forms a toner image based on image data, with a second line screen. The detector detects density unevenness of the toner pattern, formed by the image former, in a main scanning direction. The circuitry is configured to calculate a first correction amount from the density unevenness detected by the detector; create a gradation correction table that reduces the density unevenness based on the first correction amount; and correct the first correction amount by a second correction amount corresponding to the second line screen, in a case where the first line screen is different from the second line screen.

An image forming apparatus includes an image forming device, a controller, a density measurement device, and a calculator. The calculator detects a relationship (approximation line L1) between a control amount CV related to an image forming operation and a density D of an image formed on a photoconductor drum, which is an image carrier, and calculates a set value CV_TD of the control amount CV corresponding to a target density TD on the basis of the relationship. The controller forms a patch image on the photoconductor drum by using the set value CV_TD. The calculator calibrates the relationship on the basis of a difference D between a density D10 of the patch image and the target density TD, and corrects the set value CV_TD on the basis of the calibrated relationship.