A device for detecting a travel distance of a sheet is provided. The device includes a light source for irradiating the sheet surface; an imaging sensor for capturing an image of a pattern of the sheet surface by light reflected from the sheet; a discrete Fourier transformation portion for performing discrete Fourier transformation on two patterns obtained by image capturing at a time interval by the imaging sensor; a high wave number component removal portion for using a threshold determined based on a cycle of concave-convex of the sheet surface to remove a high wave number component from the two patterns having been subjected to the discrete Fourier transformation; and a travel distance calculation portion for determining a travel distance of the sheet based on a phase relationship between the two patterns from which the high wave number component removal portion has removed the high wave number component.

An image forming system includes an image forming apparatus and a management apparatus. The image forming apparatus includes a variable mechanism, a physical quantity detection unit that detects a change in physical quantity caused when a state of the variable mechanism changes, an abnormality detection unit that detects an abnormal condition, and a transmission unit that transmits detection results of the physical quantity detection unit and the abnormality detection unit to the management apparatus. The management apparatus includes a determination unit that determines a cause of the abnormal condition, and a notification unit that provides a notification that the abnormal condition is caused by a change in the state in accordance with a determination result. The determination unit determines that the abnormal condition is caused by a change in the state when the abnormal condition is detected after the change in physical quantity exceeds a threshold.

An image forming apparatus according to an embodiment includes a first roller arranged on a conveyance path of a sheet and a second roller arranged downstream of the first roller in the conveyance path. A control section calculates a deflection amount of the sheet nipped by the first roller and the second roller based on a conveyance speed of the sheet conveyed along the conveyance path. When the calculated deflection amount is smaller than a predetermined lower limit value, the control section increases the rotation speed of the first roller and decreases the rotation speed of the second roller.

An image formation apparatus includes a conveyor configured to convey a moving element on which an image is formed, a generator configured to generate a first image and a second image by shooting the conveyed moving element at different timing, a detector configured to sense a first distance between the generator and the moving element at the time of shooting of the first image and sense a second distance between the generator and the moving element at the time of shooting of the second image, and a hardware processor configured to calculate a speed of conveyance of the moving element based on the first image, the second image, the first distance, and the second distance, and output the speed of conveyance.

An image forming apparatus comprises a first roller, a second roller and a control section. The first roller is arranged on a conveyance path of a sheet. The second roller is arranged downstream side of the first roller in the conveyance path. The control section calculates a deflection amount of the sheet nipped by the first roller and the second roller based on a conveyance speed of the sheet conveyed along the conveyance path, and controls a rotation speed of at least one of the first roller and the second roller based on the calculated deflection amount.

An image forming apparatus includes: a plurality of photoreceptors; a plurality of exposure heads provided so as to correspond to the plurality of photoreceptors, respectively, each of the plurality of exposure heads including a plurality of light emitting units configured to emit light for exposing the corresponding photoreceptor, the plurality of light emitting units being arranged along a rotation axis line of the corresponding photoreceptor; and a generation unit configured to generate a line synchronization signal for each of the plurality of exposure heads to control a light emission timing in a rotating direction of the corresponding photoreceptor, the generation unit being configured to adjust a cycle of the line synchronization signal in accordance with each of the plurality of exposure heads.

An image forming apparatus includes a first sensor to detect at least one of a position of an image on a sheet or a length of the sheet; a first conveyor upstream or downstream of the first sensor in a conveyance direction; a fixing device; and circuitry. The first conveyor includes: a rubber belt; a driving roller within the rubber belt to rotate the rubber belt; a driven roller outside the rubber belt and driven by the rubber belt to convey the sheet in the conveyance direction; and a second sensor to measure a rotational speed of the driven roller. The fixing device is upstream of the first conveyor in the conveyance direction. The fixing device fixes toner onto the sheet. The circuitry is configured to control the first conveyor to convey the sheet at a target linear speed based on the rotational speed measured by the second sensor.

An image forming apparatus includes: a plurality of photoreceptors; a plurality of exposure heads provided so as to correspond to the plurality of photoreceptors, respectively, each of the plurality of exposure heads including a plurality of light emitting units configured to emit light for exposing the corresponding photoreceptor, the plurality of light emitting units being arranged along a rotation axis line of the corresponding photoreceptor; and a generation unit configured to generate a line synchronization signal for each of the plurality of exposure heads to control a light emission timing in a rotating direction of the corresponding photoreceptor, the generation unit being configured to adjust a cycle of the line synchronization signal in accordance with each of the plurality of exposure heads.