Method for protecting printed data

Heat-transfer printer (100) comprising:

• a feed system (102) for supplying the printer (100) with a plastic card (10),
• a feed roller (108) on which a transfer film (12) carrying a layer of ink to be deposited is wound,
• a recovery roller (110) on which the transfer film (12) is wound after the layer of ink has been applied to a plastic card (10),
• a print head (112) between the feed roller (108) and the recovery roller (110),
• an ejection system (104) for ejecting the plastic card (10) from the printer (100) after printing, and
• a processor (204) arranged to:
• control the simultaneous advance, over a printing length L0, of the transfer film (12) and of the plastic card (10) under the print head (112) and the heating of the print head (112) according to the text to be printed,
• controlling the rewinding of the transfer film (12) over a rewinding length L0+/−d different from the printing length L0, and the return of the plastic card (10) upstream of the print head (112),
• controlling the simultaneous advance, over another printing length, of the transfer film (12) and of the plastic card (10) under the print head (112) and the heating of the print head (112) according to the text to be printed, and
• controlling the advance of the plastic card (10) as far as the ejection system (104).