Abstract: A printing/verifying direction section in a control section directs a thermal head controller and a sheet conveying motor controller to do printing in accordance with a detection result by a sheet position detection sensor, so as to print image data in a printing image storage section on a sheet (label) by a thermal head. Further, based on printing position data from a printing data storage section, the printing/verifying direction section directs a verification section controller to operate a scanner controller so as to permit a scanner to read an image of a printed mark. The verification section controller compares the read image with printing data in the printing data storage section to judge whether the image is good or no good. When it is no good, the mark is returned to a printing position by the thermal head by a direction of a printing/verifying controller, so that the thermal head prints an overwriting image in an overwriting image storage section on the mark.

Abstract: A method of identifying a franking machine used to print franking impressions is disclosed. Ink used by the franking machine contains a chemical tag unique to each franking machine, or to a group of franking machines, and the impression printed by the franking machine is sensed to determine the identity of the tag and hence to determine the identity of the franking machine used to print the impression.