A serial printer is disclosed where the printing is performed by a printing head (22) mounted on a carriage (21) movable along the printing line, a transparent leaf (36) mounted on the carriage presses the printing support (25) (paper) against a platen (24) around the zone where the impression is performed thus considerably reducing the noise and vibration generated by the printing support vibrations during the printing.Preferably, the leaf is provided with a window (45) wherein the impression is performed in order to press the printing support against the platen all around the print zone. As the leaf is transparent, it does not preclude the visibility of what is printed. Besides, as the leaf is mounted on the carriage, when the carriage is in its travel position, the leaf does not interfere with the loading of the printing support in the printer.