Method for checking the quality of printed materials

A method for checking the quality of printed materials, which are consecutively produced in a particular production operation by means of multiple printing presses, in each case at least three printed patterns being arranged on a respective area to be printed of each of these printed materials so as to be spaced apart from one another at a distance defined for this printed material;

• these at least three printed patterns being each printed in printing methods that differ from one another;
• for checking the quality of the respective printed material, two printed patterns printed in differing printing methods being selected by an inspection system for forming a printed pattern pair;
• the printed pattern pair being assigned a scale that is defined for the distance of its printed patterns;
• prior to the start of the particular production operation, this scale being provided with a tolerance that is defined as a function of the printing methods used in the relevant printed pattern pair;
• at least in a subset taken from the quantity of all printed materials that have been consecutively produced in the particular production operation, the quality of the produced printed materials being checked in that, during the particular printing operation, in each case an instantaneous value for the respective distance between the printed patterns selected for this printed pattern pair being ascertained by means of a processing unit of the inspection system, with the printed pattern pair being the same in each case;
• the processing unit comparing the respective value of the relevant distances, which is instantaneously ascertained in each case, to the scale defined for this distance, taking into consideration the associated tolerance, and ascertaining a deviation of the respective value of the relevant distances, which is instantaneously ascertained in each case, from its defined scale, taking into consideration the associated tolerance;
• a steel engraving method and an offset printing method being used as printing methods for printing the printed patterns involved in the production of each printed material;
• an intaglio printing press being used for carrying out the steel engraving method, and an offset printing press being used for carrying out the offset printing method, characterized in that, additionally, a screen printing method is used as a printing method for printing the printed patterns involved in the production of each printed material;
• a screen printing press being used for carrying out the screen printing process;
• multiple steel plates being alternately used in the same production operation for carrying out the steel engraving process in the intaglio printing press;
• and for at least two of the steel plates involved in carrying out the steel engraving process or for all steel plates involved in carrying out the steel engraving process, the processing unit in each case selectively ascertaining the deviation of the respective value of the relevant distances, which is instantaneously ascertained in each case, from its defined scale.