Patent ID: 7722021

Claim:
A sheet processing apparatus comprising: a folding mechanism that includes paired folding rollers disposed along a transport path of a sheet, presses the sheet to a nip portion of the paired folding rollers from a direction orthogonal to a transport direction, and folds the sheet by rotating the paired folding rollers; a variable speed mechanism that includes a drive motor rotatable in a first direction and a direction reverse to the first direction, and converts a rotation force of the drive motor into a rotation output in a single direction and with a low speed first rotation speed or a high speed second rotation speed by changing a rotation direction of the drive motor; a transmission mechanism to transmit the rotation output of the variable speed mechanism in the single direction to the paired folding rollers and to rotation-control the paired folding rollers; and a control unit to control the rotation direction of the drive motor and to change a rotation speed of the paired folding rollers, wherein the variable speed mechanism includes: a first gear rotated by rotation of the drive motor; a lever rotated by a specified angle around a rotation shaft of the first gear in a rotation direction of the first gear; a planetary gear attached to the lever and engaged with and rotated by the first gear; a second gear engaged with and rotated by the planetary gear when the lever rotates in the first direction; a reduction mechanism including a third gear engaged with and rotated by the planetary gear when the lever rotates in the direction reverse to the first direction, and a fourth gear engaged with and rotated by the third gear; and a fifth gear rotated by rotation of the second gear or the fourth gear, wherein the rotation output in the single direction is obtained based on rotation of the fifth gear.