Pressing device for a sheet folding device

A pressing device, comprising:

• a shaft, and
• a press structure arranged around the shaft,
• wherein the press structure includes a part whose pressing position in a rotational direction of the shaft is different along an axis direction of the shaft, and
• wherein, the press structure rotates so that a position where the part presses the medium is changed by rotating the shaft while the medium is stopped.

A sheet processing device, comprising:

• a shaft;
• and
• at least one part arranged around the shaft, the at least one park to rotate together with the shaft,
• wherein a spiral pattern is configured to press a sheet and is arranged only on each of the at least one part, and not on any other parts arranged around the shaft, to form an overall spiral pattern, and over all of an axial extent of the shaft on which the overall spiral pattern is arranged, the overall spiral pattern does not repeat itself and is arranged over less than a full circumferential extent of the shaft.

A sheet processing roller, comprising:

• a shaft;
• and
• at least one part arranged around the shaft, the at least one part to rotate together with the shaft,
• wherein a spiral pattern is configured to press a sheet and is arranged only on each of the at least one part, and not on any other parts arranged around the shaft, to form an overall spiral pattern, and over all of an axial extent of the shaft on which the overall spiral pattern is arranged, the overall spiral pattern does not repeat itself and is arranged over less than a full circumferential extent of the shaft.

A pressing device, comprising:

• a shaft,
• a press structure arranged around the shaft;
• and
• a rotation controller configured to control rotation of the press structure,
• wherein the press structure includes a part whose pressing position in a rotational direction of the shaft is different along an axis direction of the shaft,
• wherein the press structure is to press a medium while changing a position where the press structure presses the medium, as the shaft rotates, and
• wherein the rotation controller is configured to determine a rotational direction of the press structure based on folding information about a fold formed on the medium.

A medium processing system, comprising:

• a fold processing device to fold a conveyed medium to form a fold on the medium;
• and
• a processing device to press the fold formed by the fold processing device,
• wherein the processing device includes a shaft and at least one part arranged around the shaft, the at least one part to rotate together with the shaft, and
• wherein a spiral pattern is arranged only on each of the at least one part, and not on any other parts arranged around the shaft to form an overall spiral pattern, and over all of an axial extent of the shaft on which the overall spiral pattern is arranged, the overall spiral pattern does not repeat itself and is arranged over less than a full circumferential extent of the shaft.

An image forming system, comprising:

• an image forming apparatus to form an image on the medium;
• a fold processing device to fold the medium on which the image is formed by the image forming apparatus, to form a fold on the medium;
• and
• a processing device to press the fold formed by the fold processing device,
• wherein the processing device includes a shaft, and at least one part arranged around the shaft the at least one part to rotate together with the shaft, and
• wherein a spiral pattern is arranged only on each of the at least one part and not on any other parts arranged around the shaft, to form an overall spiral pattern, and over all of an axial extent of the shaft on which the overall spiral pattern is arranged, the overall spiral pattern does not repeat itself and is arranged over less than a full circumferential extent of the shaft.