Binding unit, sheet processing device, and image forming device provided with them

A sheet processing device having a binding unit that applies water to a crimping range of sheets and then crimps the sheets, the sheet processing device comprising:

• a processing tray on which sheets are placed;
• a pair of first and second pressure teeth that mate with each other with the sheets placed on the processing tray interposed therebetween;
• a water reservoir provided on the back side of the first pressure teeth and configured to store water to be applied to the sheets;
• a pressurizing member that applies water in the water reservoir to a position at which the sheets are crimped;
• and
• a determination part that determines the number of sheets placed on the processing tray, wherein
• when the determination part determines that the number of sheets placed on the processing tray is equal to or less than a predetermined number, the sheets are crimped in a state where no water is stored in the water reservoir;
• while when the determination part determines that the number of sheets placed on the processing tray exceeds the predetermined number, the sheets are crimped by the pressure teeth pair after water in the water reservoir is applied to the sheets.

A sheet processing device comprising:

• a processing tray on which sheets are placed;
• a pair of pressure teeth that crimp the sheets placed on the processing tray with the sheets interposed therebetween;
• a water application member that applies water to a pressurization position of the sheets before crimping by the pressure teeth;
• a drive motor that drives the pressure teeth and the water application member;
• a selection unit that selects whether or not to perform water application by the water application member before crimping by the pressure teeth, the selection unit including a drive switching part that rotates the drive motor in the forward direction or reverse direction to allow selection of whether to operate both the pressure teeth and the water application member or only the pressure teeth;
• and
• a control unit that controls the drive motor so as to change the magnitude of the drive force to be applied to the pressure teeth depending on whether or not to perform water application by the water application member.