Sheet folding device, image forming apparatus and gear coupling mechanism

摘要

A sheet folding device includes two rollers, a blade, two parallel pins, and two gears. The first and second parallel pins are passed through first and second pin through-holes penetrating through first and second shaft portions in a direction perpendicular to a longitudinal direction of the shaft portions. The first and second gears have first and second shaft through-holes through which the first and second shaft portions are passed, and first and second grooves in which the first and second parallel pins are inserted, respectively. Projection portions formed on inner side wall of the second groove and projecting from both sides of the second shaft portion cause the second parallel pin to closely contact a side wall that is, in the second groove, opposite to the projection portions, and cause the second parallel pin to closely contact a portion of the second pin through-hole.

主权项

1. A sheet folding device comprising:
a first roller and a second roller configured to rotate in a state where outer circumferential surfaces thereof contact each other; a plate-like blade configured to strike a sheet member toward a nip portion between the first roller and the second roller; a first parallel pin passed through a first pin through-hole that penetrates through a first shaft portion in a direction perpendicular to a longitudinal direction of the first shaft portion, the first shaft portion being a rotation shaft of the first roller; a first gear having a first shaft through-hole and a first groove, the first shaft portion being passed through the first shaft through-hole, the first parallel pin passed through the first shaft portion being inserted in the first groove; a second parallel pin passed through a second pin through-hole that penetrates through a second shaft portion in a direction perpendicular to a longitudinal direction of the second shaft portion, the second shaft portion being a rotation shaft of the second roller; and a second gear having a second shaft through-hole and a second groove, the second shaft portion being passed through the second shaft through-hole, the second parallel pin passed through the second shaft portion being inserted in the second groove, wherein the blade strikes the sheet member such that the sheet member is folded in two and inserted in the nip portion, the first gear and the second gear rotate in conjunction with each other, the first roller rotates at a higher peripheral speed than the second roller, projection portions are formed on a side wall which is one of opposite inner side walls of the second groove, in such a way as to project from both sides of the second shaft portion toward the second parallel pin, and the projection portions cause the second parallel pin to closely contact a side wall that is, in the second groove, opposite to the side wall on which the projection portions are formed, and cause the second parallel pin to closely contact a portion of the second pin through-hole that is on an opposite side with respect to the projection portions.