A rotating suction drum passes sheet-type data carriers past at least one scanning device. The drum has an open frontal side and a zone with a plurality of channels leading to individual suction openings on the drum. A suction generator has a fan and is so disposed with respect to the drum that the entry opening for the fan passes through the open frontal side. The ratio between the sum of the areas of minimum cross section of the channels and the total area of the zone of the drum covered by the suction openings is more than 0.25.