Inkjet Print Head Nozzle Failure Compensation via Placeholder Ink
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Solution Overview
Problem
Inkjet printing systems face challenges in maintaining ink density and preventing print artifacts when a print element fails, as existing strategies do not fully mitigate the effects of missing ink, leading to visible artifacts around failing nozzles.
Innovation Solution
A multipass scanning inkjet print method is introduced, where a replacement ink with minimal color impact, such as yellow or colorless ink, is applied in the first pass to stabilize ink positions, followed by the necessary color ink in the second pass to ensure optical density, specifically targeting failing nozzles as the first element in a print line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a failing nozzle is disregarded and ink is provided by other print elements in multipass modes, then the failing nozzle is compensated, but ink displacement from adjacent lines occurs and artifacts remain visible
Solution Approach 1:
The invention applies a placeholder ink in the first pass at the position where the failing nozzle should have deposited ink. This preliminary action prevents adjacent ink from displacing by occupying the space beforehand. In subsequent passes, the missing color ink is applied over or near the placeholder, achieving both compensation and artifact prevention through the advance placement of protective material.
2Quantity of substance
If ink is transferred to neighbouring nozzles to preserve ink density, then ink density is maintained, but ink displacement artifacts still occur around failing nozzles
Solution Approach 1:
The placeholder ink is deposited in advance at the failing nozzle's position during the first pass, creating a protective barrier before adjacent ink is applied. This preliminary placement prevents the displacement artifacts that would otherwise occur, while still allowing neighboring nozzles to provide the necessary ink density through subsequent passes.
3Stability of the object's composition
If replacement ink with minimal color impact is applied in the first pass, then ink position stability is achieved, but additional printing passes are required
Solution Approach 1:
The placeholder ink is applied in the first pass to stabilize ink positions and prevent displacement. Although this requires additional passes for complete color coverage, the placeholder enables proper ink placement in subsequent passes, ultimately achieving better print quality with minimal additional time investment compared to the artifacts that would require re-printing.
Data Source
Figure 1A~1B
Figure 2A~3
AI summary
A method for applying ink at a print position of a recording medium is disclosed, wherein at least two print heads with a series of print elements are used in an at least two-pass print mode. The method comprises the steps of determining a list of failing print elements that are not capable of applying an ink droplet as required; if a failing print element is not the first print element, controlling other print elements, including the first print element, to provide the ink that would be applied by the failing print element; if a failing print element is the first print element, controlling a print element of another print head of the at least two print heads to apply an amount of ink at a line of print positions in the same pass as the failing print element passes this line of print positions and, in addition, controlling a second print element of the same print head as the failing print element to apply in a second pass the ink that would have been applied by the failing print element. Thus, a shift of ink, applied in the first pass, at print lines adjacent to said line of print positions, is prevented.