Patent ID: 7155992

Claim:
A driving force transmission mechanism comprising: a driving wheel; a follower wheel that is driven by the driving wheel; a link mechanism that engages the driving wheel and the follower wheel to make the follower wheel follow rotations of the driving wheel in a linked movement section of a rotation section of the driving wheel, and releases the driving wheel from the follower wheel in a play section of the rotation section of the driving wheel to rotate only the driving wheel; and a following rotation preventing mechanism that prevents rotations of the follower wheel in the play section to prevent the follower wheel from rotating together with the driving wheel, wherein the following rotation preventing mechanism comprises: a cam member that rotates together with the follower wheel; and an elastic member that elastically presses a cam surface of the cam member, wherein the cam surface has an arcuate section of a large diameter that slides against the elastic member when the driving wheel is engaged with the follower wheel in the linked movement section, a small diameter section adjacent to the arcuate section, and a ridge section that continuously connects the small diameter section and the arcuate section without forming a step difference, wherein the elastic member is a leaf spring with both ends thereof affixed to a support, and wherein a following rotation prevention state of the follower wheel is obtained by the ridge section of the cam surface when the ridge section of the cam surface abuts against the leaf spring under pressure in the play section of the rotation section of the driving wheel.