Sheet folding device and sheet post-processing device using same

A sheet folding device including:

• a first folding roller pair that forms a first crease in a sheet;
• a second folding roller pair that forms a second crease in the sheet;
• a first stopper member that a leading edge of the sheet transported in a transport direction is pressed against and that places the sheet into position;
• and
• a second stopper member that the first crease in the sheet is pressed against and that places the sheet into position,
• in which the leading edge of the sheet in the transport direction is pressed against the first stopper member such that a position where the first crease in the sheet is to be formed is determined, the position where the first crease is to be formed is guided into a nip portion of the first folding roller pair such that the first crease is formed in the sheet, then the first crease in the sheet is pressed against the second stopper member such that a bend is formed in the sheet and the formed bend is guided into a nip portion of the second folding roller pair such that the second crease is formed in the sheet,
• the sheet folding device further comprising:
• a sheet pressing unit that assists the formation of the bend in the sheet and that guides the bend into the nip portion of the second folding roller pair,
• wherein the sheet pressing unit includes a pressing member whose weight assists the formation of the bend in the sheet and a flexible support member that swingably supports the pressing member, and
• wherein the pressing member is arranged inside the support member.

A sheet folding device including:

• a first folding roller pair that forms a first crease in a sheet;
• a second folding roller pair that forms a second crease in the sheet;
• a first stopper member that a leading edge of the sheet transported in a transport direction is pressed against and that places the sheet into position;
• and
• a second stopper member that the first crease in the sheet is pressed against and that places the sheet into position,
• in which the leading edge of the sheet in the transport direction is pressed against the first stopper member such that a position where the first crease in the sheet is to be formed is determined, the position where the first crease is to be formed is guided into a nip portion of the first folding roller pair such that the first crease is formed in the sheet, then the first crease in the sheet is pressed against the second stopper member such that a bend is formed in the sheet and the formed bend is guided into a nip portion of the second folding roller pair such that the second crease is formed in the sheet,
• the sheet folding device further comprising:
• a sheet pressing unit that assists the formation of the bend in the sheet and that guides the bend into the nip portion of the second folding roller pair,
• wherein the sheet pressing unit includes a pressing member whose weight assists the formation of the bend in the sheet and a flexible support member that is swingable and that swingably supports the pressing member, and
• wherein the support member is connected to a pivot member.

A sheet folding device, including:

• a first folding roller pair that forms a first crease in a sheet;
• a second folding roller pair that forms a second crease in the sheet;
• a first stopper member that a leading edge of the sheet transported in a transport direction is pressed against and that places the sheet into position;
• and
• a second stopper member that the first crease in the sheet is pressed against and that places the sheet into position,
• in which the leading edge of the sheet in the transport direction is pressed against the first stopper member such that a position where the first crease in the sheet is to be formed is determined, the position where the first crease is to be formed is guided into a nip portion of the first folding roller pair such that the first crease is formed in the sheet, then the first crease in the sheet is pressed against the second stopper member such that a bend is formed in the sheet and the formed bend is guided into a nip portion of the second folding roller pair such that the second crease is formed in the sheet,
• the sheet folding device further comprising:
• a sheet pressing unit that assists the formation of the bend in the sheet and that guides the bend into the nip portion of the second folding roller pair,
• wherein the sheet pressing unit includes a pressing member whose weight assists the formation of the bend in the sheet and a flexible support member that is swingable and that swingably supports the pressing member, and
• wherein the pressing member has a cylindrical shape.