Prediction accuracy of a color misregistration amount in an image formation executed in an image forming apparatus is improved. The image forming apparatus comprises an optical box storing an optical system for irradiating a laser beam from a laser source to a photosensitive drum, a scanner temperature sensor provided near the optical box, and an environmental temperature sensor for detecting a surrounding temperature of the image forming apparatus, and a control section. When image formation is executed, the control section obtains a temperature Tscn detected by the scanner temperature sensor and a temperature Tenv detected by the environmental temperature sensor and calculates a prediction value of a position misregistration amount to the photoreceptor of the laser beam using difference between Tscn and Tenv and Tscn.

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.

An image formation apparatus that includes: first to third image formation units provided in this order in a traveling direction of a transfer target medium; a detector configured to detect first to third correction pattern formed on the transfer target medium by the first to third image formation units, respectively; and a control unit programed to control image misregistration correction based on a result of detection by the detector. The control unit causes the first and third image formation units to form the first and third correction patterns on the transfer target medium, respectively. When an amount of image misregistration between the first correction pattern and the third correction pattern is less than a predetermined value, the control unit neither causes the second image formation unit to form the second correction pattern, nor executes the image misregistration correction.

An exposing unit forms a latent-image electric potential on each photosensitive drum. A detecting toner image of each color is transferred to an intermediate transfer belt using a first potential difference between a latent-image electric potential and the potential of an intermediate transfer belt at each primary transfer portion. When the polarity of voltage to be applied from a transfer power source to a secondary transfer roller is to be switched to an opposite polarity while the detecting toner image of each color is passing through each primary transfer portion, the absolute value of a second potential difference between the potential of the intermediate transfer belt and the background electrical potential of each photosensitive drum is made equal to or greater than the absolute value of the first potential difference by a control unit.

A housing includes a first opening and a second opening, and encloses a light-emitting element and a first light receiving unit. The first opening is provided in a first light guide path, and is arranged so that light output from the light-emitting element travels toward a target surface. The second opening is provided in a second light guide path arranged between the target surface and the first light receiving unit. The first opening is an exit opening of a through-hole provided penetrating through the housing, and a shape of the through-hole is a shape in which diffracted light of the +1st order and higher orders and diffracted light of the −1st order and higher orders produced at the target surface to be irradiated are not incident on the first light receiving unit.

An image forming apparatus includes an electrophotographic process assembly, a processor, and a memory. The electrophotographic process assembly is configured to transfer a toner image formed on a photoconductive body rotating around an axis extending in a main scanning direction onto a sheet conveyed in a sub-scanning direction orthogonal to the main scanning direction. The processor and memory are configured to store a print amount in a plurality of divided sections corresponding to the main scanning direction, acquire the print amount from a monitoring section in one or more monitoring target groupings corresponding to a predetermined section included in the plurality of divided sections, calculate an integrated print amount in the monitoring section, and output information relating to the monitoring target grouping corresponding to the integrated print amount in the monitoring section.

An image forming apparatus includes an image carrier, an image forming unit, a transfer unit, a detector, a controller, an edge detector, and an abnormality detector. The detector detects developer attached to an image carrying surface at a position between a position where an image is formed and a position where the image is transferred. The controller controls the image forming unit such that a check image including an edge that extends in a direction intersecting the moving direction of the image carrying surface is formed in a region of the image carrying surface that passes through the detection position. The edge detector determines a position of the edge based on a detection status of the developer. The abnormality detector determines whether or not the image former is abnormal based on the position of the edge.

In an image forming apparatus, a controller (a) determines a bright potential of a photoconductor drum at calibration, (b) adjusts a development bias and thereby determines as an intermediate reference development bias value a value of the development bias so that a toner density based on an output of a reflection-type optical sensor is equal to an intermediate reference density lower than a target density, (c) determines as an intermediate reference effective potential a difference between the intermediate reference development bias value and the bright potential at calibration, and (d) determines a development bias value corresponding to the target density by linear interpolation based on the intermediate reference effective potential and a virtual zero density effective potential. The virtual zero density effective potential is a difference between a development bias and a bright potential of the photoconductor drum when a transmission density is virtually zero.

An image forming apparatus operable at a plurality of image forming speeds includes a pattern detection unit configured to detect a registration correction pattern at a first image forming speed, a writing start timing determination unit configured to determine writing start timing at which an electrostatic latent image is started to be written on a photosensitive member by a light beam emitted from a light source, and a storage unit configured to store in advance a correction amount for correcting the writing start timing. When the image forming apparatus operates at the first image forming speed set in advance, an image is formed at the writing start timing determined by the writing start timing determination unit. When the image forming apparatus operates at a second image forming speed, an image is formed at a writing start timing corrected based on the correction amount and a speed ratio.

An image forming apparatus includes an image bearer, a toner image forming device, a plurality of image density detectors, and a controller. The plurality of image density detectors are disposed at predetermined intervals opposite the image bearer in a width direction of the image bearer. The controller causes the toner image forming device to form toner image patterns having an identical density at the plurality of positions on the image bearer and the plurality of image density detectors detects a density of the toner image patterns. Based on the detected density of the toner image patterns, the controller identifies multiple cyclic fluctuations of the density of the toner image patterns and adjusts an image forming condition based on the multiple cyclic fluctuations of the density of the toner image patterns to decrease an amplitude caused by the multiple cyclic fluctuations of the density of the toner image patterns.