A sheet folding processing apparatus performs folding processing on continuously conveyed sheets without lowering productivity. A sheet folding processing apparatus includes a conveyance roller pair, a folding roller pair forming a plurality of fold lines by bending a sheet conveyed from the conveyance roller pair in Z-shape, an additional folding roller and a lower folding guide arranged downstream of the folding roller pair to face each other and pressing the fold line of the sheet in corporation with each other, and a controller controlling operation of the above. The controller controls the folding roller pair to convey the sheet with the fold line downstream in a conveyance direction until the fold line passes through the additional folding position by a predetermined conveyance amount, to return the sheet upstream by reversely rotating the folding roller pair, and to position the fold line to the additional folding position for additional folding processing.

A sheet folding apparatus includes: a rotor having a first peripheral surface and a second peripheral surface with a radius smaller than that of the first peripheral surface and configured to convey a sheet; and a guide member configured to be movable between a first position where it guides a sheet being conveyed by the rotor and a second position retracting from the first position. The guide member is disposed so as to move from the second position to the first position while passing within the rotation locus of the first peripheral surface of the rotor.

An image forming system includes an image forming apparatus, a pressure sealing processing apparatus, and a control unit. The control unit is configured to permit execution of the pressure sealing processing process by the pressure sealing processing apparatus on a recording material of which a grammage is smaller than a predetermined grammage, and is configured not to permit execution of the pressure sealing processing process by the pressure sealing processing apparatus on a recording material of which a grammage is equal to or more than the predetermined grammage.

Provided is a finisher including a post-processor and an online suppliers. The post processor including a binding path, a binding unit to perform any one or combination of processes of a saddle stitching process and a folding process on a sheet-type medium on the binding path, and a manual supply slot to manually be supplied with the sheet-type medium towards the binding path. The online supplier to receive the sheet-type medium from an external device and supply the sheet-type medium to the binding path. A housing accommodating the post-processor and the online supplier and including an online supply slot to receive the sheet-type medium through the online supply slot from the external device.

An image forming apparatus includes a processing tray, a post-processing controller, and a detection sensor. The processing tray is configured to support a sheet or a sheet bundle on which a post-processing is to be executed. The post-processing controller is configured to execute the post-processing on the sheet positioned on the processing tray. The detection sensor is configured to detect an object in a predetermined detection range including a space above the processing tray. The post-processing controller stops execution of the post-processing when the detection sensor detects the object at a determination timing other than a timing at which passage of the sheet or the sheet bundle through the detection range is estimated.

A sheet processing apparatus includes a transport path to guide a sheet transported in a predetermined transport direction, a rotating body pair capable of transporting the sheet in a first direction for nipping the sheet transported to the transport path thereby drawing the sheet to perform folding processing, and in a second direction for switching back the sheet to return to one direction side in the transport direction, a press member for pressing the sheet folded by the rotating body pair in the second direction, and a support portion for supporting the press member, where the support portion is disposed on the side opposite to the rotating body pair with the transport path therebetween and on the other direction side opposite to the one direction side in the transport direction with a nip line for connecting between the nip portion and a front end portion of the folding blade therebetween.

A sheet processing apparatus performs folding processing so that one end of a sheet exists inside the folded sheet. The sheet processing apparatus includes a transport path to guide a transported sheet, a rotating body pair capable of transporting the sheet in a first direction to perform folding processing, and in a second direction for switching back the sheet subjected to the folding processing, a folding blade that pushes the sheet to a nip portion of the rotating body pair, a press member that presses the sheet folded by the rotating body pair in the second direction, and a shift section that shifts the press member for pressing the sheet. In switching back the sheet, a control section controls transport of the sheet so that the one end of the sheet is halted within a region between the press member and a guide face of the transport path.

A post-processing apparatus according to an embodiment includes a processing tray, a post-processing section, a sensor, and a control section. A sheet supplied from an image forming apparatus is led into the processing tray through a lead-in path. The post-processing section applies post-processing to the sheet sent from the processing tray. The sensor detects an object passing a detection space in the lead-in path. The control section controls operation of the post-processing section based on a time in which the sensor detects the object.

Pressure-responsive particles include pressure-responsive base particles and first inorganic oxide particles, in which the pressure-responsive base particles contain a styrene-based resin which contains styrene and other vinyl monomers as polymerization components and a (meth)acrylic acid ester-based resin which contains at least two kinds of (meth)acrylic acid esters as polymerization components and in which a mass ratio of the (meth)acrylic acid esters to all polymerization components is 90% by mass or higher, Db/Da which is a ratio of a number average particle diameter Db of the first inorganic oxide particles to a number average particle diameter Da of the pressure-responsive base particles is 0.05 or higher and 0.25 or lower, the pressure-responsive particles have at least two glass transition temperatures, and a difference between a lowest glass transition temperature and a highest glass transition temperature is 30° C. or higher.

An image forming apparatus includes a processing tray, a post-processing controller, and a detection sensor. The processing tray is configured to support a sheet or a sheet bundle on which a post-processing is to be executed. The post-processing controller is configured to execute the post-processing on the sheet positioned on the processing tray. The detection sensor is configured to detect an object in a predetermined detection range including a space above the processing tray. The post-processing controller stops execution of the post-processing when the detection sensor detects the object at a determination timing other than a timing at which passage of the sheet or the sheet bundle through the detection range is estimated.