Vacuum pulldown of print medium in printing system

A method for printing on a movable print medium in a printing system, inducing:

• providing a first linehead defining one or more print zones, the first linehead adapted to jet liquid onto a first side of the movable print medium in the one or more print zones;
• providing one or more vacuum transport rollers having a porous sleeve rotatable around a non-rotating core, wherein the rotatable porous sleeve is engaged by the movable print medium that exerts a force on the porous sleeve causing it to rotate, and wherein at least one vacuum transport roller is disposed adjacent to a second side of the movable print medium and opposite the first linehead, and is aligned with one of the one or more print zones of the first linehead, and wherein the core includes a vacuum manifold that outputs a vacuum force that operates on the second side of the movable print medium through the porous sleeve;
• moving the movable print medium through the printing system;
• applying the vacuum force proximate to the second side of the movable print medium such that at least a portion of the movable print medium is deflected causing an increase in a wrap angle of the movable print medium around the vacuum transport roller(s);
• jetting liquid from the first linehead onto the first side of the movable print medium to form a print;
• providing a dryer and one or more dryer vacuum transport rollers disposed adjacent to the second side of the movable print medium and aligned opposite to the dryer such that the dryer vacuum transport roller(s) produces a vacuum force that operates on the second side of the movable print medium to deflect the movable print medium causing an increase in the wrap angle of the movable print medium around the dryer vacuum transport roller(s);
• and
• using the dryer to dry the liquid applied to the print medium.

A method for printing on a movable print medium in a printing system, including;

• providing a first linehead defining one or mom print zones, the first linehead adapted to jet liquid onto a first side of the movable print medium in the one or more print zones;
• providing one or more vacuum transport rollers having a porous sleeve rotatable around a non-rotating core, wherein the rotatable porous sleeve is engaged by the movable print medium that exerts a force on the porous sleeve causing it to rotate, and wherein at least one vacuum transport roller is disposed adjacent to a second side of the movable print medium and opposite the first linehead, and is aligned with one of the one or more print zones of the first linehead, and wherein the core includes a vacuum manifold that outputs a vacuum force that operates on the second side of the movable print medium through the porous sleeve;
• positioning the vacuum manifold asymmetrically relative to a vertical centerline of the vacuum transport roller such that the wrap angle of the movable print medium on the upstream side is different from the wrap angle of the movable print medium on the downstream side of the vacuum transport roller;
• moving the movable print medium through the printing system;
• applying the vacuum force proximate to the second side of the movable print medium such that at least a portion of the movable print medium is deflected causing an increase in a wrap angle of the movable print medium around the vacuum transport roller(s);
• and
• jetting liquid from the first linehead onto the first side of the movable print medium to form a print.