US 4,852,485 AGranted

Method of operating an autotypical color offset printing machine

OwnerFelix Brunnerinventor

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Abstract

The invention relates to a method, a control apparatus and aids for the achievement of a uniform printing result on an autotypically operating multicolor printing press. In addition to solid densities and/or screen dot sizes, selected relationships between solid densities and/or screen dot sizes of different printing colors are determined at measuring patches simultaneously printed within the color zones. If they fall outside of the tolerances associated with them, a corrective intervention is made in the printing process by actuating the regulators of the inking units. For the control of the inking units, the first aid provided, instead of the conventional single color meausring patches, is combination measuring patches which are formed by the overprinting of single color measuring patches. Since the measurement data obtained at combination measuring patches do not agree with the data obtained at single color measuring patches, they are corrected accordingly prior to being processed to control signals for the regulators in the printing units. A second aid consists of a device for determining the color balance in the printing result.

Claims18

Dependent claims

A method of operating a multicolor printing press having a plurality of printing units for printing a multicolor picture composed of color picture elements too small for the human eye to dissolve, each unit having an ink foundation for feeding one of a plurality of different printing inks onto a substrate, and also having a plurality of adjustable ink regulating means for controlling feeding of said inks onto a plurality of adjacent zones of said substrate;

said method comprising the steps of:
successively printing a plurality of pictures with said inks onto said substrate;
successively printing measuring patches with said inks onto said substrate such that said inks within said patches have characteristics of a group of characteristics containing at least one of the following:
solid density and screen dot sizes;
repeatedly determining said characteristics of said inks within said patches;
repeatedly determining selected relationships between the characteristics of different inks within said patches;
associating first tolerance ranges with said relationships;
determining whether said relationships are inside or outside said first tolerance ranges;
and controlling said regulating means such that said relationships fall within said first tolerance ranges, to thereby achieve uniform printing of said pictures.

6 more elements

Dependencies are inferred from the claim text.