US 11,752,760 B2
Method of printing printed products using printing nozzles without defects and defective nozzles that have been compensated for
Ralf Tita, Hirschhorn (DE); and Hans Köhler, Edingen-Neckarhausen (DE)
Assigned to Heidelberger Druckmaschinen AG, Heidelberg (DE)
Filed by Heidelberger Druckmaschinen AG, Heidelberg (DE)
Filed on Jan. 19, 2023, as Appl. No. 18/156,772.
Claims priority of application No. 10 2022 102 523.3 (DE), filed on Feb. 3, 2022.
Prior Publication US 2023/0241885 A1, Aug. 3, 2023
Int. Cl. B41J 2/045 (2006.01); G06T 7/00 (2017.01); B41J 29/393 (2006.01)
CPC B41J 2/04508 (2013.01) [B41J 2/04586 (2013.01); B41J 29/393 (2013.01); G06T 7/0004 (2013.01); B41J 2029/3935 (2013.01); G06T 2207/30144 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method of printing printed products using nozzles that are free from defects and defective nozzles that have been compensated for, the method comprising steps of:
providing a printing machine with printing nozzles for printing the printed products and for printing a test chart;
printing the test chart with a multiplicity of test fields onto a printing substrate being transported, creating the test fields as halftones with a respective tonal value from among a specified set of tonal values and being printed by multiple printing nozzles, every test field including an unprinted line created by a printing nozzle not being activated and not printing, compensating for the unprinted line by at least one active neighboring nozzle, selecting a compensation value for the neighboring nozzle from a specified set of compensation values, and specifying and using a multiplicity of pairs formed of a tonal value and a compensation value for the test chart;
using every specified pair formed of a tonal value and a compensation value multiple times in the test chart, and for every pair, creating a corresponding number of test fields at locations spaced apart from one another in the test chart;
assigning a characteristic value determining a quality of the compensation value to every measuring field in the analyzing step, the characteristic value representing a homogeneity of the test field in the x direction, and determining a best characteristic value in terms of a specified criterion and the compensation value to be applied during printing to print the printed products for every one of the tonal values;
recording an image of the test chart by using at least one image recording system;
using at least one computer to analyze the image and to determine the compensation value for the printing operation to print the printed products; and
printing the printed products.