Method for detecting defective printing nozzles in an inkjet printing machine

US10603923B2 · kind B2 · utility

Assignee

• Heidelberger Druckmaschinen AG · DE

Inventors

• Johannes Muehl · Ennepetal, DE
• Hans Koehler · Graz, AT
• Roland Stenzel · Nuremberg, DE
• Andreas Henn · Trochtelfingen, DE
• Martin Mayer · Ladenburg, DE
• Steffen Neeb · Bensheim, DE
• Frank Muth · Karlsruhe, DE
• Jan Krieger · Heidelberg, DE
• NICKLAS RAYMOND NORRICK · Heddesheim, DE
• Mina Hakim Latif Abosetta · Mannheim, DE

Key dates

• Filing date: Feb 11, 2019
• Grant date: Mar 31, 2020
• Expiry date: Feb 11, 2039

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B41J2029/3935
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A method for detecting defective printing nozzles in an inkjet printing machine includes printing a multi-row printing nozzle test chart formed of horizontal rows of equidistant vertical lines periodically underneath one another, with only printing nozzles in a print head contributing to every row of the test chart corresponding to the horizontal rows. An area coverage element geometrically associated with the test chart is printed, both elements are recorded by an image sensor and analyzed by the computer. The computer analyzes the recorded area coverage element to detect print defects and allocates defects to a region of geometrically close printing nozzles. An analysis of the test chart in the region identifies nozzles causing the defect. Defective printing nozzles are detected based on thresholds, the detected printing nozzles are then compensated, and in the analysis of the recorded area coverage element, influences of the sensor are eliminated by shading correction.