Abstract: A control device for on the fly printing machines, especially machines for franking envelopes, comprises a printing device comprising a rotary print head actuated by a first motor and carrying on a portion of its surface a printing active part. A conveyor device for conveying the envelopes is actuated by a second motor and feeds the envelopes into contact with the printing device at a given conveyor speed and evacuates franked envelopes. The rotation speed of the first motor is optimized so that the tangential speed of the print head is held equal to the conveyor speed during a printing phase corresponding to the period during which an envelope is in contact with the active printing part and as close as possible to the conveyor speed during a complementary catch-up phase. The conveyor speed is optimized so that the conveyor speed is as low as possible whilst preventing overlapping of envelopes arriving on the conveyor device.

Abstract: A printing machine for webs of paper or the like has a flat horizontal screen which is stationarily but removably mounted in the machine frame above the path of intermittent longitudinal movement of the web. A hollow air-permeable counterpressure cylinder is mounted below the path of the web and is reciprocable relative to the screen with a carriage which further supports a printing medium applying unit at a level above the screen. The cylinder is rotated during the printing stroke while a first squeegee of the applying unit forces printing medium through the screen and into contact with the web. During the next-following return stroke, the cylinder is held against rotation and a second squeegee of the applying unit spreads out the printing medium on the screen. At the same time, the web is advanced forwardly through a preselected distance.