A graphics printer including a device for ensuring contact between a print medium and a guiding platform at the printing zone of the graphics printer, including a suction chamber, a suction means for creating a partial vacuum in the suction chamber located beneath the guiding platform and a plurality of orifices formed across the width of the platform communicating with the suction chamber, the print medium being guided over the platform covering a variable portion of the width of the platform as a function of the format of the print medium, the suction chamber being provided with one or more partitions separating the chamber width-wise into compartments while leaving a limited air passage section between the adjacent compartments.