Patent ID: 6682191
Filing Date: 2004-01-27
Classification: B41J,B65H

Abstract:
A vacuum drum assembly for a printing machine, the assembly comprising:a drum having a length and a periphery with an array of passageways distributed along its length and around its periphery to permit air to flow from outside the drum to inside the drum in response to reduced air pressure inside the drum; and an array of valve members, each valve member being movable between a closed position in which that valve member restricts at least one of the passageways and an open position in which the restriction of the at least one passageway is reduced, and wherein a at least one of said valve members is normally closed and is opened by a pressure difference, wherein the assembly is arranged such that, when a partial area of the drum is covered with material to be printed, at least some of the valve members for the passageways adjacent an edge of said partial area are open, and the valve members for the passageways which are not covered by the material and are not adjacent an edge of said partial area are closed.