A sheet tray provided with first and second trays respectively having first and second supporting surfaces. The second tray slidably assembled, in a first direction, to the first tray. The first and second supporting surfaces are configured to support sheets thereon. The first tray and the second tray have a first guide portion and a second guide portion which are formed at central parts, in a second direction perpendicular to the first direction, respectively. The second guide portion is configured to slidably contact the first guide portion to guide the slide movement of the second tray. A first separation regulating part formed on the first guide portion, and a second separation regulating part formed on the second guide portion are configured to engage with each other in the vertical direction to prevent separation of the first and second trays in the vertical direction, exceeding a particular dimension.

A coupling mechanism of the present disclosure includes a drive transmission member, a coupling member and a biasing member. The drive transmission member includes a shaft portion and an engagement pin. The coupling member includes a plurality of engagement protrusions and a holding protrusion which is smaller than the engagement protrusion. The holding protrusion makes contact with the engagement pin in a state where the engagement pin makes contact with the pressing surface. A load in a reverse rotation direction is applied from the holding protrusion to the engagement pin when the coupling member is reversely rotated.

The present invention provides an electrophotographic apparatus in which the deterioration of electrical properties in repetitive use is suppressed even in the case where an electrophotographic photosensitive member absorbs moisture under a high-temperature and high-humidity environment. An undercoat layer of the electrophotographic photosensitive member provided in the electrophotographic apparatus contains (α) a metal oxide particle, (β) a particular benzophenone compound and (γ) a compound represented by the following formula (2).

##STR00001##

wherein R.sup.11 to R.sup.15 each independently represent a hydrogen atom, a hydroxy group, a halogen atom, an alkyl group, an alkoxy group or an amino group and A.sup.1 represents an alkenyl group having 2 or more and 4 or less carbon atoms.

A sensor includes a light emitter and a photodetector. The light emitter outputs light with which a toner pattern or a surface material of an image carrier is irradiated. The photodetector receives reflection light from the toner pattern or the surface material. The sensor light intensity control unit provides a control voltage to the light emitter and thereby controls light intensity of the light emitter. The density determining unit determines a toner density on the basis of output of the photodetector. Further, the density determining unit (a) determines as a correction parameter a first-order coefficient of the control voltage of the light emitter for an output voltage of the photodetector corresponding to reflection light from the surface material, (b) determines a correction amount corresponding to the correction parameter and the toner density, and (c) corrects the toner density on the basis of the correction amount.

An optional device of the present disclosure is attachable and detachable with respect to an image forming apparatus via a connection member fitted to a side face of a main body of the optional device. The connection member includes a shaft, a connector, and a lock member. The shaft is supported by the main body to be slidable in an axial direction. The connector is fixed to the shaft and coupled to the image forming apparatus. The lock member is capable or restricting movement of the shaft in the axial direction. A position of the connector is adjusted by releasing the restriction placed on the shaft by the lock member and then sliding the shaft in the axial direction.

A damper mechanism has first and second rail members, a biasing member, and a slide member. The first rail member is fixed inside the opening/closing member along the up/down direction, and has an oblong guide hole formed therein extending along the longitudinal direction. The second rail member has fixed to a top end part thereof an engaging pin inserted through the guide hole, and has a bottom end part swingably supported on the apparatus main body. The biasing member biases the first and second rail members in a direction in which these approach each other. The slide member is made of resin fixed to the engaging pin, slides while in contact with the first rail member and the opening/closing member, and prevents contact between the engaging pin and an inner circumferential rim of the guide hole.

An image forming system includes an image forming unit configured to form an image on a sheet and provided in an apparatus body, a first sheet processing device provided in a first housing and configured to perform a first binding processing, without using a needle, on the sheet that is formed with the image and stacked, and a second sheet processing device provided in a second housing that is different from the first housing and configured to perform a second binding processing, using a needle, on the sheet that is formed with the image and stacked. The first housing and the second housing are mounted on the apparatus body. At least a portion of the first housing is positioned within a range exclusively occupied by a rectangular space defined by a maximum outer dimension of the apparatus body. The second housing is positioned outside the rectangular space.

A method for feeding uneven media from a high capacity feeder includes rotating the pages in a stack 180° every 100-250 pages. This is only done with non-flat pages, such as, envelopes, pages with labels thereon, etc., which create tilted stacks and limit the number of pages that can be placed in the high capacity feeder. Rotating the pages 180° distributes the uneven build-up of the pages and creates a relatively flat stack, allowing the high capacity feeder to be filled to capacity. A camera or sensor placed in the high capacity feeder will detect the orientation of the stack on the fly so the image can be rotated accordingly.

A fixing tool includes a pair of arms, a holding portion, and a claw portion. The arms are capable of being inserted into and pulled out from through holes formed respectively in a sheet support plate, which supports a sheet stored in a sheet feeder of an image forming apparatus such that the sheet can be lifted and lowered, and in a bottom portion of the sheet feeder. The holding portion is provided so as to project from a predetermined position on each of the arms and capable of holding the sheet support plate and the bottom portion. The claw portion is provided so as to project inward from a distal end of each of the arms and capable of being inserted between an integrated circuit mounted in the image forming apparatus and a mounting target portion which the integrated circuit is mountable to and detachable from.

The image forming apparatus includes a control unit that executes a supply operation to supply a toner charged with a regular charge polarity, to at least one abutting portion of a plurality of abutting portions, at the time of image non-formation, the plurality of abutting portions being formed by a plurality of cleaning members and a plurality of image bearing members, the control unit determining an image bearing member to which the most amount of the toner charged with the regular charge polarity is supplied, based on image formation information, the image formation information being information about an image formation executed before the supply operation is executed.