An image forming apparatus includes: a photoreceptor; an exposing unit comprising a light window and a light source; a developing unit; a transfer unit; a sensing unit comprising a sensor sensing a toner image of the transfer unit; and a shutter unit configured to open or close the light window and the sensor, wherein the shutter unit includes: a motor configured to have a driving shaft rotating in a first rotation direction and a second rotation direction; a first shutter part configured to open or close the light window by receiving driving force transferred from the driving shaft when the driving shaft rotates in the first and second rotation directions; and a second shutter part configured to open or close the sensor by receiving driving force transferred from the driving shaft when the driving shaft rotates in the second rotation direction.

An image forming apparatus includes: a housing in which a light source, a laser scanning member, a light detecting portion configured to detect light incident on a predetermined position in a scanning path of the light scanned by the laser scanning member, and a scanning lens configured to cause the light scanned by the laser scanning member to be scanned at an equal speed on an image carrier, are disposed; a temperature gradient detecting portion, configured to detect a temperature gradient of the housing, a heater configured to heat the image carrier or a sheet; and a correction processing portion configured to correct the emission start timing based on the temperature detected by the temperature gradient detecting portion, and a predetermined expression, and change content of the expression based on an operation state of the heater at a start of an image formation process.

An image forming apparatus comprises a sensor which emits light with a spot diameter serving as a predetermined size to a pattern for position detection formed on a transfer medium conveyed by a conveyance section, and outputs a read signal corresponding to reflected light of the emitted light; a processing circuit which generates a differential signal obtained by differentiating the read signal output by the sensor, and outputs a signal obtained through an exclusive OR of the read signal and the differential signal obtained by differentiating the read signal; and a control section configured to specify a position at which a image forming section forms a image on the basis of the signal output by the processing circuit.

An image forming apparatus includes a plurality of image forming units, an intermediate transfer member, a detection unit, and a controller. The controller is configured to control the plurality of image forming units to form, on the intermediate transfer member, a pattern image including a first detection image having a reference color among the plurality of detection images and a second detection image having another color among the plurality of detection images. The first detection image and the second detection image are superimposed on a predetermined detection image. The controller is configured to control the detection unit to detect the amount of color misregistration which is related to a relative position of the first detection image and the second detection image, and to determine an adjustment value for adjusting an image write start timing of the other color different from the reference color.

An image forming apparatus capable of performing color misregistration correction at image forming speeds while reducing downtime. Image forming units form images of different colors. The formed images are transferred to an intermediate transfer belt. A pattern sensor detects color misregistration amounts of color patterns formed on the intermediate transfer belt. A CPU causes the image forming units to form first color patterns at a first speed and the pattern sensor to detect first color misregistration amounts, and causes the former to form second color patterns at a second speed different from the first speed and the latter to detect second color misregistration amounts. The CPU determines third color misregistration amounts at a third speed based on the first and second color misregistration amounts. The third speed is different from the first and second speeds.

An image forming apparatus including a controller, which starts rotation of a rotary polygon mirror when a predetermined condition is satisfied, rotates the rotary polygon mirror at a predetermined rotation speed based on a first pulse in a first state in which light beams are not emitted from a light source, thereafter starts emission of the light beams, switches a rotation control based on the first pulse to a rotation control based on the second pulse, and rotates the rotary polygon mirror at the predetermined rotation speed based on the second pulse in a second state in which the light beams are emitted from the light source, and thereafter detects a temperature of a drive circuit board by a temperature detector, and corrects color misregistration using a detected temperature of the temperature detector and the detection result of a pattern detector.

An image forming apparatus comprises a sensor which emits light with a spot diameter serving as a predetermined size to a pattern for position detection formed on a transfer medium conveyed by a conveyance section, and outputs a read signal corresponding to reflected light of the emitted light; a processing circuit which generates a differential signal obtained by differentiating the read signal output by the sensor, and outputs a signal obtained through an exclusive OR of the read signal and the differential signal obtained by differentiating the read signal; and a control section configured to specify a position at which a image forming section forms a image on the basis of the signal output by the processing circuit.

A natural frequency measuring device includes a receiving unit and a measuring unit. The receiving unit receives information of an image formed on a recording medium with vibrations of different frequencies provided to a member used to form the image. The measuring unit measures a natural frequency of the member from a frequency response characteristic using a misregistration amount of the image represented by the information of the image received by the receiving unit.

An image forming apparatus includes a first image forming unit configured to form a first image in a chromatic color, a second image forming unit configured to form a second image in black, an intermediate transfer member, a sensor, a first adjustment unit configured to adjust the image forming position for the black based on an adjustment value, a second adjustment unit configured to adjust image forming position based on an adjustment condition, and a generation unit configured to generate the adjustment condition. The generation unit generates a first adjustment condition based on a user instruction relating to a first test image having chromatic color on a sheet input from the input unit. The generation unit generates a second adjustment condition based on the reading result of the second test image having black on a sheet from a reading device.

An image forming apparatus transfers toner images of respective colors, formed on photosensitive drums, onto an intermediate transfer belt conveyed in a predetermined direction to thereby form a color toner image. A steering roller tilts the intermediate transfer belt in a direction orthogonal to the conveying direction. A first sensor detects a position of a belt lateral end of the belt, and when controlling driving of the steering roller based on a detection result of the first sensor, a controller performs predetermined filtering on the detection result, to thereby control the driving of the steering roller according to the detection result subjected to the predetermined filtering.