Franking device with tamper protection

An apparatus for generating a print image on an image carrier composed of a first partial image and a second partial image disposed transversely offset relative to a first direction, comprising:

• an ink drop-ejecting printhead;
• a printhead positioner connected to said printhead for generating a relative motion between an ink drop-ejecting printhead and said image carrier in a first step along said first direction for generating said first partial image on said image carrier, generating a transverse offset between said printhead and said image carrier in a second step in a second direction proceeding transversely to said first direction, and generating a relative motion between said printhead and said image carrier in a third step along said first direction for generating said second partial image on said image carrier, said transverse offset in said second step producing an overlap region between said first partial image and said second partial image on said image carrier, said printhead in each of said first and third steps, ejecting a plurality of ink drops, including first ink drops, from said printhead onto said image carrier in said overlap region;
• and
• a time control unit connected to said printhead that repeats said first, second and third steps while varying a waiting time interval between an end of printing in said first step and a beginning of printing in said third step, according to a prescribed function that varies said waiting time interval in multiples of a variation interval equal to a quotient of a prescribed longitudinal offset and an average speed of the relative motion between the printhead and the image carrier in said third step.