An image forming apparatus includes a first plurality of image forming sections that form a first toner image for adjustment and transfer the first toner image for adjustment to a medium; a second plurality of image forming sections that form a second toner image for adjustment and transfer the second toner image for adjustment to the medium; and a detection device configured to detect a misregistration between the first toner image for adjustment transferred to the medium and the second toner image for adjustment transferred to the medium.

An example shutter unit includes a motor including a driving shaft to rotate in a first rotation direction and to rotate in a second rotation direction opposed to the first rotation direction, a first shutter part to selectively expose a light window by receiving a driving force transferred from the driving shaft when the driving shaft rotates in the first rotation direction or the second rotation direction, and a second shutter part to selectively expose a sensor by receiving the driving force transferred from the driving shaft when the driving shaft rotates in the second rotation direction.

An image forming apparatus comprises a first temperature detector to detect a temperature of a first portion of an optical scanning device in a printer. The first portion is proximate to a heat generating element in the optical scanning device. A second temperature detector is provided to detect a temperature of a second portion of the optical scanning device, which is farther from the heat generating element than the first portion. A controller is configured to perform alignment control for correcting a color positional shift of the printer when either a detected temperature change of the first portion is greater than or equal to a first threshold value or a detected temperature change of the second portion is greater than or equal to a second threshold value.

A measuring device a measurement unit configured to measure an image on a sheet, the measurement unit including a light emitting portion configured to illuminate the sheet with light, and a detecting portion configured to detect light reflected by the sheet; a supporting unit supporting the measurement unit; and a driving unit configured to move the measurement unit supported by the supporting unit in a scanning direction. A size, in the scanning direction, of a detectable range of the detecting portion in which the detecting portion is capable of detecting the reflected light from the sheet is larger than a size, in a sub-scanning direction perpendicular to the scanning direction and a normal direction of a surface of the sheet, of the detectable range of the detecting portion.

An image forming apparatus includes: a first forming unit that forms a superimposed toner image, in which yellow, magenta, and cyan toner images are superimposed on one another, on a first intermediate transfer unit; a second forming unit that is located downstream of the first forming unit in a recording-medium transport direction and that forms a black toner image on a second intermediate transfer unit; a first transfer part that transfers the superimposed toner image formed on the first intermediate transfer unit by the first forming unit to a recording medium; and a second transfer part that is located downstream of the first transfer part in the recording-medium transport direction and that transfers, in a superimposed manner, the black toner image formed on the second intermediate transfer unit by the second forming unit to the superimposed toner image on the recording medium.

A deviation detection device to detect a deviation of a rotator includes a contact member disposed in contact with the rotator and configured to move, following a deviation of the rotator in a width direction of the rotator. The deviation detection device further includes a deviation detector configured to detect a direction of the deviation and a deviation amount of the rotator based on a displacement of the contact member, and a wear detector configured to detect a state in which an amount of wear of the contact member has reached a threshold.

The image forming apparatus stores a plurality of candidate formulas in a memory. Each of the candidate formulas are a formula for calculating a prediction formula for calculating a predicted value of the color misregistration amount based on an external exposure device temperature which is a temperature of the atmosphere around the exposure device, an external machine temperature, and a heater temperature of a heater which heats the plurality of image forming units. The CPU determines the prediction formula from the plurality of candidate formulas according to the external exposure device temperature, the external machine temperature, and the heater temperature. The CPU calculates the predicted value of the color misregistration amount using the determined predicted formula, and perform a color misregistration correction according to the calculated predicted value.

An image forming apparatus includes: a first forming unit that forms a superimposed toner image, in which yellow, magenta, and cyan toner images are superimposed on one another, on a first intermediate transfer unit; a second forming unit that is located downstream of the first forming unit in a recording-medium transport direction and that forms a black toner image on a second intermediate transfer unit; a first transfer part that transfers the superimposed toner image formed on the first intermediate transfer unit by the first forming unit to a recording medium; and a second transfer part that is located downstream of the first transfer part in the recording-medium transport direction and that transfers, in a superimposed manner, the black toner image formed on the second intermediate transfer unit by the second forming unit to the superimposed toner image on the recording medium.

An image forming apparatus includes: plural image forming units that each include plural image forming sections and a first intermediate transfer body to which toner images formed by the plural image forming sections are transferred through first transfer; plural second transfer sections provided in correspondence with the plural image forming units to transfer the toner images on the first intermediate transfer body to a recording medium through second transfer; and a detection device that detects the toner images downstream of a most downstream one of the second transfer sections.

An image forming apparatus includes a controller configured to execute: a task that measures a plurality of first color patterns; a task that, on the basis of a first output value corresponding to a measurement result of the first color patterns, determines a threshold value; a measurement task that measures a plurality of second color patterns; and a task that detects an amount of color misregistration on the basis of a result of a comparator comparing a second output value corresponding to a measurement result of the second color patterns with a threshold value corresponding to each of the second color patterns. In the measurement task, the controller controls whether or not to set the threshold value to the threshold value corresponding to each of the second color patterns on the basis of the first output value.