Paper sheet stamp apparatus

A paper sheet stamp apparatus comprising:

• a conveying mechanism adapted to convey a paper sheet at a constant speed via a conveying path;
• a sensor configured to detect the conveyed paper sheet to acquire a stamp timing;
• a stamp hub configured to stamp a first surface of the paper sheet detected by the sensor;
• a backup roller adapted to rotate in a rolling contact with a second surface of the paper sheet so as to press the first surface of the paper sheet onto the stamp hub;
• and
• a first driving portion adapted to independently drive the stamp hub so as to rotate the stamp hub at the constant speed, when at least the stamp hub contacts the paper sheet,
• wherein the stamp hub includes an effective region in which a letterpress is formed and a non-contact region in which the hub does not roll-contact the first surface of the paper sheet on an outer peripheral surface of the hub, and
• the first driving portion accelerates and rotates the stamp hub stopped in a home position in which the non-contact region is disposed opposite to the conveying path so that the speed of the outer peripheral surface reaches the constant speed at a time when the effective region starts contacting the first surface, rotates the stamp hub at the constant speed when the effective region roll-contacts the first surface, and decelerates and stops the stamp hub in the home position after the effective region is detached from the first surface.