Printing – Inkers – Roller
Reexamination Certificate
1999-10-13
2001-08-28
Asher, Kimberly (Department: 2854)
Printing
Inkers
Roller
C101S483000, C101S349100, C101S327000
Reexamination Certificate
active
06279474
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method for the metered transfer of ink onto an ink roller in a printing unit of a rotary offset printing press, wherein the ink is applied under pressure to the casing surface of the ink roller. The invention further relates to a device for performing the method.
It has become known heretofore from the published German Patent Document DE 29 51 651 A1 to apply printing ink in a printing unit metered by pump pressure onto an ink roller of an inking unit by means of ink nozzles. Such a device replaced conventional devices for applying ink, wherein an ink duct roller is supplied with ink from an ink duct. In both cases, the ink applied to the ink roller is then distributed in a printing unit, which is formed of many ink rollers and consequently expensive, until a required quantity in a layer of predetermined thickness is attained on a form or application roller which deposits the ink on a blanket cylinder in an offset printing press. Devices according to the foregoing patent publication do not measure up to the requirements as to quality imposed on offset printing.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method and device for transferring ink in a printing unit of an offset printing press wherein the two-dimensional ink profile required for printing in an offset printing press is applied to an ink roller with an as exactly as possible metered ink quantity, in order thereby to reduce the expense for conventional inking units.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for metered transferring of ink to an ink roller in a printing unit of an offset printing press, wherein the ink is applied under pressure to a casing surface of the ink roller, which comprises determining digital data for effecting a two-dimensional ink distribution on the casing surface corresponding to an ink consumption, and ejecting ink droplets for applying ink to the ink roller from at least one nozzle of an ink-jet unit controlled by means of a control device in accordance with the digital data.
In accordance with another aspect of the invention, there is provided a device for metered transferring of ink to an ink roller in a printing unit of an offset printing press, comprising a computer having an input for digital data for producing printing plates by effecting a two-dimensional ink distribution on a casing surface of the ink roller corresponding to an ink consumption, and an ink-jet unit with capillary nozzles connected to the computer so as to be electronically controllable by the computer for ejecting ink droplets for applying ink to the ink roller in accordance with the digital data.
In accordance with another feature of the invention, the ink roller is an inking roller disposed in rolling contact with an ink form roller for transferring onto the ink form roller ink applied directly to the inking roller from the capillary nozzles of the ink-jet unit.
In accordance with a concomitant feature of the invention, the ink roller is an ink form roller disposed adjacent to the capillary nozzles of the ink-jet unit wherefrom ink is applied directly onto the ink form roller.
The application or use of the general principle widely known with regard to ink-jet printers, wherein liquid ink is ejected from continuously open capillary tubes either by a very high pressure or in an electrophysical manner permits a very precise metered ink transfer both in breadthwise, i.e., lengthwise, direction of the respective ink roller, as well as in circumferential direction thereof, suitable digital data being derivable from data determined for a printing form and being in part directly applicable, respectively.
A conventional inking unit formed of several rollers is entirely or to a considerable extent replaced by an ink-jet unit when applying the method according to the invention, the ink-jet unit, if necessary or desirable, being a customary ink-jet printer with a conventional computer control. Considerable costs for the production of an inking unit are thereby avoided.
Because the length of the transfer path of the ink in a printing unit according to the invention is very short, the inking unit reacts rapidly to required variations in the ink application or deposition on a printing form. Furthermore, waste or spoilage can be reduced during proof printing, because the operation of letting the printing ink run in requires a considerably shorter time than for conventional expensive inking units having many ink-unit rollers. Whereas only one-dimensional zonal ink key presetting values are provided over the breadth or length of a cylinder in conventional methods of presetting the inking unit, according to the invention of the instant application, two-dimensional ink key presetting values are employed by which, during the application or deposition of the ink, the ink consumption dependent upon the printed image is taken into account.
Thus, provided in accordance with the invention of the instant application is an ink jet apparatus with capillary nozzles directed to an ink roller transferring the ink directly to the ink form roller which surrenders the ink to the plate cylinder. In particular cases, the capillary nozzles of the ink-jet apparatus can also be directed directly to an ink form cylinder which transfers or applies the ink onto the plate cylinder. It is conducive to a further reduction in cost that the manufacturing tolerances for ink-jet apparatuses for performing the method according to the invention can be greater than for ink-jet printers. The number of capillary nozzles does not have to be as great as for printers in order to achieve the objectives striven for with the invention.
With the above and other objects in view there is also provided, in accordance with the invention, 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;
ejecting ink drops from ink-jet nozzles of the ink-jet printing apparatus under control of the control device;
applying a quantity V of ink from the ink-jet nozzles 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.
In two alternative embodiments, the inking roller is an ink form roller in rolling contact with the printing form, or the inking roller is in rolling contact with an ink form roller that is in rolling contact with the printing form.
There is also provided, in accordance with the invention, 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;
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 scre
Asher Kimberly
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Lerner Herbert L.
Stemer Werner H.
LandOfFree
Method and device for transferring ink in a printing unit of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for transferring ink in a printing unit of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for transferring ink in a printing unit of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2441762