Apparatus for holding a printing medium on a rotary drum and ink jet

Abstract

An apparatus for holding a printing medium on a rotary drum, includes a rotary drum, a suction device, a medium holding mechanism and a medium removing device. The drum has a recess at its outer surface to extend along its rotation center line and rotates at a predetermined speed. A region of the outer surface, which is adjacent to a rearward end of the recess along the rotation direction, is smaller in the diameter than the remaining of the outer surface. The suction device holds by suction the medium onto the outer surface. The holding mechanism has a hook in the recess and selectively drives the hook between close and open positions. At the close position, the hook is placed over the adjacent region while being prevented from radially outwardly projecting from the remaining of the outer surface, and at the open position it is distanced from the adjacent region. When the medium arrives at the adjacent region, its leading end is held by the hook shifted from the open position to the close position and cooperated with the adjacent region and, when the drum rotates a specific number, the hook is returned to the open position. The removing device removes the medium from the outer surface when the drum rotates the specific number and the hook has moved from the close position to the open position.