A sheet stacker includes a sheet stacking member, a biasing force applier, an angle setter, and a regulator. The sheet stacking member has an upstream portion in a sheet conveyance direction. The upstream portion is movable in a vertical direction. The biasing force applier is configured to apply a biasing force to bias the sheet stacking member upward. The angle setter is configured to set an angle of the sheet stacking member in the sheet conveyance direction, relative to a sheet conveying portion, between a first angle and a second angle. The regulator is configured to regulate movement of the sheet stacking member in a case in which the upstream portion of the sheet stacking member is located closer to the sheet conveying portion at either the first angle or the second angle.

A measurement apparatus includes a sheet stacking portion provided above a first conveyance path and on which a second sheet discharged out of a second conveyance path is stacked. The sheet stacking portion includes an extension tray configured to support the sheet discharged out of the second conveyance path and to be movable between a first position and a second position, the first position being a position where the extension tray is located inside a width of the measurement apparatus in the horizontal direction, and the second position being a position where the extension tray is located above an upstream apparatus and is overlapped with the upstream apparatus when viewed in a gravity direction.

An image forming apparatus that is capable of preventing discharged sheet adhesion while lowering degradation of productivity. A print unit prints an image on a sheet based on a print job. A fixing unit fixes the image primed on the sheet to the sheet. The sheet to which the image is fixed is discharged to a discharge tray. A counter counts discharged sheet number that is the number of sheets discharged to the discharge tray during a continuous print operation. A controller controls the print unit so as to lower productivity that is discharging sheet number per unit time in response to increase in the discharged sheet number counted by the counter and so as to recover the productivity in a case where the sheets discharged to the discharge tray are removed in a state where the productivity is lowered.

Disclosed is an image forming apparatus, including: a first guide guiding one surface of a sheet downstream of a fixing unit fixing a toner image on the sheet and upstream of discharging rollers discharging the sheet to a stacking portion in a sheet conveying direction; a second guide facing the first guide, the second guide guiding the other surface of the sheet; protrusions with openings provided on the second guide in a sheet width direction orthogonal to the sheet conveying direction; recesses provided on the first guide in the sheet width direction, the recesses facing the protrusions; and a blower unit blowing air toward the sheet via the openings provided on the second guide, wherein a corrugated shape is formed in the width direction on the sheet to which air is blown by the protrusions provided on the second guide and the recesses provided on the first guide.

A sheet discharge device of the present invention includes discharge rollers configured to transport a sheet in a predetermined transport direction and to discharge the sheet to a discharge tray, and an upper discharge tray disposed above the discharge tray with a space being interposed therebetween. A bottom face of the upper discharge tray that faces the discharge tray includes a guide rib extending in an oblique direction inclined relative to the transport direction.

An image forming apparatus includes an image forming portion; a fixing device including a fixing member, a heating portion and a pressing member; a pressure switching mechanism configured to switch pressure between the fixing member and the pressing member; and a controller capable of executing an operation in an image forming mode in which the image is capable of being formed on the envelope by causing the pressure switching mechanism to switch the pressure to first pressure when an instruction to form the image on an address side of the envelope is inputted and by causing the pressure switching mechanism to switch the pressure to second pressure higher than the first pressure when an instruction to form the image on a non-address side of the envelope is inputted.

Disclosed is a post-processing apparatus configured to be coupled to an image forming apparatus or another post-processing apparatus. The post-processing apparatus includes: a post-processing unit that performs post-processing to a sheet that is conveyed; and a standby path arranged on an upstream side or a downstream side of the post-processing unit and capable of holding the sheet. The post-processing unit performs the post-processing in a state in which the sheet is partly in the standby path.

In an image forming method according to the present invention, an image is formed by removing residual charge from the image on an image recording medium. The image forming method includes formation of an image for forming a toner image by fixing a toner on the image recording medium and application of voltage from a voltage applier, the voltage having a polarity reverse to a polarity of a surface potential of the toner image. The toner includes toner base particles and an external additive. The toner base particles include a crystalline polyester resin.

An image forming apparatus includes a plurality of photosensitive members; a scanner unit including light sources, a rotatable polygonal mirror, and reflecting members; and a fixing portion. Parts of the laser beams emitted from the light sources are reflected by the rotatable polygonal mirror toward the fixing device side, and rest parts of the laser beams are reflected by the rotatable polygonal mirror toward a side opposite from the fixing device side. Of the parts of the laser beams reflected by the rotatable polygonal mirror toward the fixing device side, the laser beam reflected toward the reflecting member provided at a position remotest from the rotatable polygonal mirror travels downward relative to a horizontal direction. A rotational axis of the rotatable polygonal mirror is inclined relative to a vertical direction.

An image formation apparatus according to an embodiment may include: an apparatus housing including a stacker formed on a periphery of the apparatus housing, wherein the stacker includes an opening; an image formation part provided in the apparatus housing and configured to form an image on a medium; and a fixation unit detachably attached in the apparatus housing and configured to fix the image formed by the image formation part on the medium, wherein in a state where the fixation unit is attached in the apparatus housing, a part of the fixation unit is exposed through the opening of the stacker to constitute a part of the stacker such that the opening of the stacker allows the fixation unit to be taken out from the apparatus housing therethrough.