An image forming apparatus includes a developing roller configured to develop an electrostatic latent image on a photosensitive drum to form a toner image; a belt onto which the toner image is transferred; a detection unit configured to detect a density of an image for detection formed on the belt; and a controller configured to perform hue adjustment based on a detection result of the detection unit. The image forming apparatus performs image formation in a second mode using a color gamut different from a color gamut in a first mode, and the controller obtains a lookup table, which indicates a correlation between image data to be used and input image data in the second mode, based on the detection result in the first mode and a correlation of density between the first mode and the second mode.

Downtime relating to formation and detection of a detection image is reduced. An image forming apparatus includes a controller configured to calculate a first conversion unit to convert a gradation of input image data so that density output for the input image data becomes a first density output characteristic based on a first detection result of the detection image detected by a density sensor in a first mode. The controller generates a second conversion unit to convert the gradation of the input image data so that the density output for the input image data becomes a second density output characteristic in a second mode based on the detection result in the first mode and correction information, and further updates the correction information based on a second detection result of the detection image detected by the density sensor in the second mode and the first detection result.

An image forming apparatus includes a print engine including a photosensitive drum forming an image on an image forming medium, a charging member charging the photosensitive drum, a power supply to provide a charging power supply having a reference charging voltage to the charging member, a sensor to detect an image density of an image formed on the image forming medium, and a processor to control the power supply to change a magnitude of voltage of the charging power supply within a predetermined voltage range at predetermined periods, and to identify an occurrence of a background with respect to the photosensitive drum based on an image density detected by the sensor while the charging power supply is changed.

An image forming apparatus includes an exposure device, a developing device, an intermediate transfer body, a sensor, and a controller. The exposure device may irradiate light corresponding to a test pattern onto a photoconductor, the developing device may supply a developing agent to the photoconductor to form, on the photoconductor, a toner image corresponding to the test pattern, the intermediate transfer body may receive the toner image corresponding to the test pattern formed on the photoconductor, and a sensor may sense the test pattern transferred onto the intermediate transfer body. The controller may control the exposure device to adjust the irradiated light so the test pattern becomes a contone pattern having a uniform tone, and may diagnose a condition of a component of the image forming apparatus based on the sensed test pattern.

An image forming apparatus includes an image carrier, a developing device, a control unit, and a density measuring unit. An electrostatic latent image is formed on the surface of an image carrier. A developing device supplies toner to the image carrier and develops the electrostatic latent image formed on the image carrier to form a toner image. The density measuring unit measures the toner density of the plurality of first patch toner images formed by the developing device. The control unit calculates a relationship between the toner density of the plurality of first patch toner images measured by the density measuring unit and the applied voltage applied to the developing device when the plurality of first patch toner images are formed, and adjusts the applied voltage based on a calculation result.

The control unit executes a mode of detecting the image density of the toner image for control. The control unit sets the target toner density so that the target toner density becomes smaller than before execution of the mode and also set the target transfer current so that the target transfer current becomes smaller, in a case where the image density detected in the mode is higher by a predetermined threshold or more than a reference density.

An image forming apparatus according to one embodiment includes an image carrier that moves in a first direction, a developing device, a detector, and a determination unit. The developing device uses a developer on the surface of the image carrier to forma strip-shaped image inclined with respect to the width direction perpendicular to the moving direction of the image carrier. The detector detects the density difference occurring in the strip-shaped image formed on the surface of the image carrier while moving in the width direction. The determination unit determines based on a detection result by the detector whether or not there is an abnormality.

An image forming apparatus includes an exposure unit provided with a rotatable polygon mirror including a plurality of reflecting surfaces and scanning a light beam emitted from a light source, to expose a photosensitive member with the light beam according to an image information. A determining unit determines an end of lifetime of the exposure unit based on a detecting result of density of a toner image detected by two detecting units at a first timing and a detecting result of density of the toner image detected by the two detecting units at a second timing after the first timing.

An image forming apparatus includes an image bearing member, an exposure unit, a developing member, and a control unit. The exposure unit exposes a surface of the image bearing member to light to form an electrostatic latent image. The developing member develops the electrostatic latent image by using toner to form a toner image. In image formation based on input image data, the control unit uses the exposure unit to control a maximum gradation value of the toner image to be formed on the image bearing member surface, based on a repetition length of a dither pattern. The control unit performs control so that the maximum gradation value is larger in a case where a first dither pattern having a first length as the repetition length is used than where a second dither pattern having a second length longer than the first length as the repetition length is used.

A laser scanning unit includes a light source portion, a scanning portion, a first correction portion, and a second correction portion. The light source portion outputs a plurality of light beams. The scanning portion scans the plurality of light beams to form a plurality of electrostatic latent images, respectively corresponding to a plurality of colors including at least one reference color and at least one non-reference color, in an image forming portion. The first correction portion applies an external mechanical force to an optical element located in a path of a reference beam, corresponding to the reference color, among the plurality of light beams to correct distortion of a scan line of the reference beam. The second correction portion controls the light source portion to correct distortion of a scan line of a non-reference beam, corresponding to the non-reference color, among the plurality of light beams.