Sheet folding device and sheet post-processor provided with the same

A sheet folding device that performs a folding process with respect to a sheet, comprising:

• a sheet conveyance path on which the sheet is conveyed;
• a first folding conveyance path that extends to intersect with the sheet conveyance path;
• a first folding roller pair that is composed of:
• a first roller;
• and
• a second roller configured to form a first folding nip by being brought into pressure contact with an upstream side of the first roller in a conveyance direction of the sheet conveyed on the sheet conveyance path,
• the first folding roller pair being configured to fold in two the sheet passing through the first folding nip and to convey the sheet to the first folding conveyance path;
• a first folding guide that is disposed to be opposed to the first folding nip with the sheet conveyance path interposed therebetween and reciprocates between a folding position at which the first folding guide approaches the first folding nip to guide a to-be-folded part of the sheet conveyed on the sheet conveyance path to the first folding nip and a retracted position at which the first folding guide is away from the first folding nip;
• and
• a conveyance roller that makes pressure contact with the second roller so as to form, together with the second roller, a first assist roller pair that conveys the sheet along the sheet conveyance path,
• wherein
• the first folding guide has a pivot fulcrum on a downstream side relative to the first folding nip in the conveyance direction and is supported so as to be pivotable about the pivot fulcrum between the folding position and the retracted position,
• the sheet folding device further includes a jam clearance guide that is capable of opening and closing the sheet conveyance path to remove the sheet, and
• in a state where the jam clearance guide is opened, the first folding guide is pivotable to such a position as to open an area above the first folding nip with respect to the sheet conveyance path.