Patent ID: 7699300

Claim:
A sheet post-processing apparatus comprising; stitching means for stitching with staples a sheet bundle conveyed along a conveyance path, the stitching means stitching the sheet bundle at plural places thereof along a straight line orthogonal to the conveyance direction; folding means including a pair of folding rollers disposed downstream of the stitching means on the conveyance path and a blade that pushes the sheet bundle into a contact portion of the pair of folding rollers; a folding roller drive motor that drives the pair of folding rollers; and control means for controlling the driving or stopping operation of the folding roller drive motor in correspondence to the process of folding the sheet bundle, the control means uses a voltage-type inverter comprising plural switching elements to generate a pulse width modulation control signal, and the control means pulse width modification drives the folding roller drive motor to vary its speed wherein the control means varies the speed of the folding roller drive motor during a period before the blade comes in contact with the sheet bundle, a speed of the folding roller drive motor during a period when the sheet bundle after folding work is being transported to a discharge port, a speed of the folding roller drive motor during a period when the sheet bundle is being discharged, and a speed of the folding roller drive motor during a period when the folding roller drive motor is being returned to a home position, and wherein the pulse width modulation control signal corresponding to a torque command is ON to switch ON the switching elements to apply the drive current in a direction, and the control means pulse width modification applies the drive current in an opposite direction when the pulse width modification control signal is OFF to switch OFF the switching elements.