Rotor for a rotor-type locking device operated by a key, said rotor presenting: a central chamber; a series of slots; locking tumblers with nib, in which at least one tumbler is brought into the unlocked position by a displacement in a direction different from the unlocking direction of at least two other tumblers, the nibs of said tumblers extending along a same face of the chamber. A printing device reads the print designation file from the memory card, then takes out the image data to be printed from the memory card in accordance with the read information and executes printing. The pixel arrays are related in that one or more luminance pixels of the luminance pixel array cover each pixel of the color pixel array. The incisions preferentially stretch over two thirds of the height of the block and run virtually parallel to its sides, so that the fins have a rectangular cross-section.