An image forming apparatus includes a density detector, a determination unit, and a change unit. The density detector detects a density of a patch image formed on an image carrier over plural places. The determination unit determines whether plural detection results of the density detector are within a threshold. When the number of determination results, by the determination unit, that the density of the patch image is not within the threshold exceeds a predetermined number, the change unit changes (i) a detection timing at which the patch image is detected by the density detector or (ii) a formation position of the patch image on the image carrier.

There is provided a method for controlling an electrophotographic apparatus including forming a first measurement image by performing first halftone processing on image data, forming a second measurement image by performing second halftone processing different from the first halftone processing on the image data, measuring densities of the first measurement image and the second measurement image, calculating a density difference between each of densities of the measurement images, determining whether the density difference satisfies a predetermined reference value, and applying a surface treatment on an electrophotographic photosensitive member if the density difference does not satisfy the reference value, during a non-image formation period.

An image forming apparatus includes: an image forming portion having an image carrying member, a charging device, an exposing device, and a developing device; a developing voltage power supply; a control portion; and an image density sensor. The developing device has a developer carrying member that carries two-component developer and a toner concentration sensor. The control portion senses toner concentration during calibration or during first image formation after calibration for correcting image density based on the sensing result from the image density sensor. If the difference Vtarget−V between the output value V of the toner concentration sensor actually sensed and a target value Vtarget of the toner concentration sensor to be observed when the toner concentration equals a reference concentration is equal to or larger than a predetermined value, the control portion performs calibration again when the amount of toner consumed after calibration reaches a predetermined threshold value.

An image forming apparatus which includes a rotary member and a detecting member configured to detect light from a surface of the rotary member. A controller is configured to acquire information relating to a position on the rotary member in a moving direction thereof based on a detection result obtained by the detecting member. The surface of the rotary member has, in a part of the rotary member in its moving direction, an area with a different detection result obtained by the detecting member based on a shape of the surface of the rotary member. The controller acquires the information relating to the position on the rotary member in the moving direction based on the detection result of detecting light from the surface of the rotary member by the detecting member.

An image forming apparatus includes an image forming portion, a high-voltage generation circuit, a current detection portion and a control portion. The image forming portion includes an image carrying member, a charging device, an exposure device and a developing device which includes a developer carrying member for carrying a developer including a carrier and a toner. The control portion can perform a development ghost prediction mode that includes a step of measuring the amount of charge of the toner within the developing device at the time of non-image formation, a step of measuring, as a carrier current, the direct-current component of a development current when the amount of development of the toner is 0 [mg/cm.sup.2] and a step of estimating the level of occurrence of development ghost and the cause of occurrence based on the amount of charge of the toner and the carrier current which are measured.

An image forming apparatus is provided. The image forming apparatus includes a sensor to detect a toner concentration, and a processor to control a rendering of image-forming data to form an image on an image forming medium, according to a level of toner concentration saving that is adjusted based on the detected toner concentration.

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.

An image forming apparatus is provided. The image forming apparatus includes an image forming part to form a pattern including at least one white dot line and at least one black dot line on an image forming medium using a photoconductive drum. A registration sensor is to sense an amount of light reflected from the image forming medium. A processor is to determine a state of the photoconductive drum based on the amount of sensed light in the pattern.

A printer includes an image forming unit to form a toner image on an image receptor by using a toner containing fluorescent additives for generating light in a predefined wavelength band in response to light in an invisible wavelength band, transfer the toner image to a print medium, and fix the toner image on the print medium, a photodetector including a light emitting unit configured to irradiate light in an invisible wavelength band to the toner image accommodated in one of the image receptor and the print medium, and a light receiving unit to detect reflected light from the toner image, and a controller to control a printing operation of the image forming unit, based on a detection signal from the light receiving unit.

Provided is an operation method of an image forming apparatus, the operation method including according to a color registration pattern that is a standard for determining an overlapping degree of respective color images of a plurality of colors to form a color image, transferring respective developers with the plurality of colors onto an intermediate transfer body; obtaining patch data of patches of the plurality of colors transferred according to the color registration pattern onto the intermediate transfer body. The patch data is compared with reference patch data corresponding to the color registration pattern, and based on a result of the comparing, noise data corresponding to noise is detected from the patch data. Standard patch data is obtained by removing the noise data from the patch data, and performing color registration based on the standard patch data.