Mark printing/verifying device, mark printing/verifying method and mark printing control method

A mark printing/verifying device, comprising a thermal head for printing a mark on a sheet, a sheet conveying motor for conveying the sheet, a sheet position detector for detecting a position of the sheet, and an image reader, located downstream from said thermal head in a sheet conveying direction, for reading an image of a printed mark being the mark printed by said thermal head, and a control section for controlling them,

• said control section, comprising:
• a printing image storage means for storing image data indicating a mark in unit of a dot resolution in a main scan direction being a sheet width direction and a sub-scan direction being the sheet conveying direction of said thermal head;
• a printing data storage means for storing printing position data and printing data of the mark;
• a thermal head controller for selectively permitting heating elements of said thermal head to generate heat in accordance with the image data;
• a sheet conveying motor controller for controlling said sheet conveying motor;
• and
• a printing/verifying direction means for directing said thermal head controller and sheet conveying motor controller to do printing in accordance with the sheet position detected by said sheet position detector, and directing said image reader to read the image of the printed mark based on the printing position data, and including
• a function of comparing the image of the printed mark read by said image reader with the printing data to judge whether the printed mark is good or no good based on predetermined criteria included in the printing data, and, when the mark is no good, performing invalid printing on a sheet printed with the mark.