Method and device for transferring ink in a printing unit of an offset printing press
AssigneeHeidelberger Druckmaschinen AG
InventorRoland Liebl
Life of this patent
Estimating the term…
Abstract
Method for metered transferring of ink to an ink roller in a printing unit of a rotary offset printing press, wherein the ink is applied under pressure to a casing surface of the ink roller, includes determining digital data for effecting a two-dimensional ink distribution on the casing surface corresponding to an ink consumption. The ink is ejected in droplets from an ink-jet unit to the ink roller. The ink-jet unit has nozzles which are aligned with one dimension of the two-dimensional ink distribution. The ink-jet nozzles of the ink-jet unit are controlled by a control device in accordance with the digital data.
Claims21
Method for metered transferring of ink to an ink roller in a printing unit of a rotary offset printing press, which comprises:
- determining digital data for effecting a two-dimensional ink distribution on a casing surface of an ink roller corresponding to an ink consumption;
- providing an ink-jet unit with a plurality of ink nozzles and aligning the ink nozzles with one dimension of the two-dimensional ink distribution;
- and
- ejecting ink droplets under pressure for applying ink to the casing of the ink roller from the ink nozzles of the ink-jet unit controlled by means of a control device in accordance with the digital data.
A method for inking a printing form on a cylinder of a rotary offset printing press, having an inking system with an inking roller and an ink-jet printing apparatus acting across a length of the inking roller, wherein a number of ink drops that can be expelled per unit of length onto the surface of the inking roller with the ink-jet printing apparatus is substantially less than a number of screen dots generated per unit of length on the printing form, the method which comprises:
- inputting into a control device signals containing an ink quantity V output per area element of a printing form onto an offset cylinder;
- applying a quantity V of ink from ink-jet nozzles of the ink-jet printing apparatus under control of the control device to area elements of the surface of the inking roller corresponding to the ink quantity V output to the corresponding area element of the offset cylinder;
- and
- renewing the ink quantity output to the offset cylinder in each area element during a revolution of the printing form cylinder.
A method for inking a rotating printing form having a printing form surface being imaged with screen dots carrying ink during printing, which comprises:
- defining a plurality of screen dots within a specific one of a plurality of area elements dividing a printing form surface;
- applying ink with an inking roller having a roller surface divisible into area elements corresponding to the area elements of the printing form, one of the area elements of the inking roller being a specific area element of the inking roller;
- expelling ink drops with an ink jet unit onto the inking roller, and applying a volume of the ink to the specific area element of the inking roller equivalent to an ink volume transferred away from the specific area element of the printing form in printing;
- wherein the ink drops are applied by the ink jet unit onto the specific area element of the inking roller in a number substantially less than a number of screen dots located within the specific element of the printing form.
Dependencies are inferred from the claim text.