A sheet accommodating apparatus includes a first cassette provided so as to be drawn out in a draw-out direction, a second cassette disposed adjacent to the first cassette in a vertical direction, one holder member, and a first light emitting member and a second light emitting member that are supported by the holder member. The first cassette includes a first accommodating container and a first cover. The second cassette includes a second accommodating container and a second cover. The first cover has a first hole provided in a position opposing the first light emitting member in the draw-out direction such that the light emitted from the first light emitting member passes therethrough. The second cover has a second hole provided in a position opposing the second light emitting member in the draw-out direction such that the light emitted from the second light emitting member passes therethrough.

An image forming apparatus includes a first processor configured to control a transporter that transports a sheet and a first image forming section that forms an image on the sheet transported by the transporter, and a second processor configured to control a second image forming section that forms an image on the sheet transported by the transporter. The first processor and the second processor are contained in a single housing. When the first processor receives an image formation command from outside the housing and determines to perform an image forming process at the first image forming section, the first processor is configured to perform transport preparation for transporting the sheet at the transporter and receive, from the second processor, a completion notification corresponding to a preparation command, for performing image formation preparation in the second image forming section, transmitted to the second processor via an inside of the housing, and subsequently cause the transporter to transport the sheet and the first image forming section to form the image. If the first processor ascertains that an independent process involving not forming the image at the first image forming section but forming the image at the second image forming section is to be performed, the first processor is configured to perform the transport preparation before receiving the completion notification, and cause the transporter to transport the sheet after receiving the completion notification.

An electro-conductive member for an electrophotographic image forming apparatus for which a change in resistance value is small even when a large current is applied at a high voltage for a long period of time is provided. The electro-conductive member includes a support having an electro-conductive outer surface and an electro-conductive layer on the outer surface of the support, in which the electro-conductive layer has a matrix including a cross-linked product of a first rubber and domains dispersed in the matrix, the domains include a cross-linked product of a second rubber different from the first rubber and an electrically conductive agent, and the cross-linked product of the second rubber has, in a molecule, a structural unit represented by Structural Formula (I).

[—(CH.sub.2).sub.n—O—]  Structural Formula (I)

In Structural Formula (I), n is an integer of 1 to 3.

A development system for an image forming apparatus includes a photosensitive drum having a drive plate to receive a driving force to rotate the photosensitive drum. The drive plate is provided on an end of the photosensitive drum. The development system also includes a developing roller having a clutch mechanism to dampen a force generated when the clutch mechanism engages the drive plate of the photosensitive drum. The clutch mechanism is provided on an end of the photosensitive drum.

A processor generates an extraction image by extracting, from a test image, a target specific part that is a horizontal stripe extending in a horizontal direction or a noise point. The processor derives a vertical data sequence from a target area in the extraction image and converts the vertical data sequence to primary conversion data of a frequency domain. The processor converts, to secondary conversion data of a space domain, correction data that is obtained by removing, from the primary conversion data, data of frequency bands other than a particular frequency band corresponding to a target specific part that was determined as having periodicities. The processor classifies the target specific parts into periodic specific part and non-periodic specific part by comparing positions of the target specific parts with a peak position in a waveform represented by the secondary conversion data.

A processor determines a cause of an image defect based on a test image that is obtained through an image reading process performed on an output sheet output from an image forming device. The processor extracts a vertical stripe part extending along a sub scanning direction in the test image. Furthermore, the processor determines which of predetermined two types of cause candidates is a cause of the vertical stripe part, based on a distribution of a pixel value sequence along a main scanning direction that crosses the sub scanning direction, in a target part including the vertical stripe part in the test image.

A sheet post-processing apparatus that performs post-processing on a sheet on which an image is formed includes: a punch hole forming portion; and a sheet bundle forming portion that has a conveyance portion, stops a first sheet on a conveyance path, and conveys a second sheet after the first sheet to a position overlapping the first sheet to form a sheet bundle. The sheet post-processing apparatus includes a shift portion to make a shift so that a relative position between the first sheet and the second sheet in a direction orthogonal to a conveyance direction becomes a relative position at which the second sheet does not overlap a punch hole of the first sheet to make the second sheet overlap the first sheet, and forms a sheet bundle in which sheets overlapped with each other are deviated in a width direction.

In an image forming device, a photosensitive drum forms an image on a sheet based on the image formation data. The roller conveys the sheet. A motor provides the roller with driving force to rotate the roller. A controller acquires an advance command which is received from the external terminal prior to reception of the image formation data. The advance command includes option information. The controller determines a rotational speed of the roller based on the option information. The rotational speed is determined to be changeable depending on the optional information. The controller performs a preliminary process before the photosensitive drum forms an image on the sheet based on the image formation data. The preliminary process is to control the motor so that the roller rotates at the rotational speed determined in the determining

A processor selects a target sheet from a plurality of predetermined sheet candidates in accordance with selection information that is input via an input device. Furthermore, the processor derives feature information regarding a noise point from a target image that is obtained through an image reading process performed on an output sheet output from an image forming device, the noise point being a dot-like noise image included in the target image. Furthermore, the processor determines whether or not the noise point is a dot-like sheet noise by applying the feature information to a determination algorithm that corresponds to the target sheet, the sheet noise being included in a sheet of the output sheet itself, the determination algorithm being one of a plurality of determination algorithms that respectively correspond to the plurality of sheet candidates.

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.