Patent ID: 7819519

Claim:
An ink jet printing apparatus including a printhead arrangement for printing an image on a substrate in a pass of the substrate past the printhead arrangement in a printing direction, the printer comprising: a printhead arrangement including a plurality of ink jet printheads for emitting droplets towards a surface of the substrate to form the image, wherein the printhead arrangement extends across substantially the full width of the substrate in a direction perpendicular to the printing direction; a plurality of rollers arranged to move the substrate past the printheads during the emission of the droplets from the printheads to print the image; a pressure source arranged to apply a negative gauge pressure to the substrate to hold the substrate to the rollers in the region of the printhead arrangement; a mask element arranged between first and second rollers of the plurality of rollers such that a first gap is defined between the mask element and the first roller as well as a second gap between the mask element and the second roller, wherein the mask element throttles airflow caused by the negative gauge pressure through the first and second gaps; wherein the apparatus is adapted to hold the printheads substantially stationary while the image is printed in a pass of the substrate past the printhead arrangement.