Printing Apparatus Ink Discharge Control for Gloss Uniformity
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Solution Overview
Problem
Serial printing apparatuses using pigment ink face issues with gloss unevenness due to the limited amount of resin composition in the ink, leading to reduced gloss and density when high-density printing is performed, especially noticeable in bidirectional printing modes.
Innovation Solution
A printing apparatus with a print head that controls the usage rate of nozzles and the amount of chromatic ink discharged, where the chromatic ink with a higher resin composition is primarily used in succeeding passes to maintain a large resin composition on the printing medium, reducing gloss unevenness even without achromatic inks other than black.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-density printing is executed with black ink containing a large amount of pigment composition and a relatively small amount of resin composition, then the density of output color ink increases, but the gloss level is reduced and gloss unevenness occurs due to diffused reflection of light
Solution Approach 1:
The patent divides the ink discharge process into multiple passes (first pass, second pass, third pass) with different nozzle usage patterns. In the first pass, only black ink is discharged. In the second pass, both black ink and chromatic ink are discharged. In the third pass, only chromatic ink is discharged. This segmentation allows different resin compositions to be applied at different stages to achieve both high density and uniform gloss.
Solution Approach 2:
The patent changes the parameters of ink composition by using different ink types (black ink with pigment composition and resin composition, chromatic ink with pigment composition and larger amount of resin composition) and controlling the discharge amount and timing of each ink type across multiple passes to optimize both density and gloss uniformity.
2Productivity
If the number of scans or time interval between scans is reduced for faster printing, then productivity increases, but gloss unevenness occurs more easily due to insufficient resin composition distribution
Solution Approach 1:
The patent applies preliminary action by discharging black ink containing resin composition in the first pass before chromatic ink is discharged. This preliminary resin layer provides a base that prevents gloss unevenness even when subsequent passes are executed quickly, allowing faster printing while maintaining gloss uniformity.
Solution Approach 2:
The patent maintains continuity of useful action by executing multiple passes without significant time intervals, ensuring that resin composition from different passes accumulates continuously on the printing medium. This continuous application of resin across passes maintains gloss uniformity while enabling fast printing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses gloss unevenness by ensuring a sufficient amount of resin composition remains on the printing medium, enhancing the gloss and density of printed images, particularly in high-density black ink printing.
Implementation Method 1
the density of output color ink appears to be reduced due to the diffused reflection of light
Data Source
AI summary
A printing apparatus has a plurality of nozzles including preceding nozzles that discharge ink onto a printing medium before ink discharge of the other nozzles, and succeeding nozzles that discharge ink onto the printing medium after the ink discharge of the preceding nozzles, and if the amount of black ink discharged on the printing target region is larger than a predetermined amount, the printing apparatus discharges a smaller amount of chromatic ink than the amount of the discharged black ink onto the printing target region from the plurality of nozzles so that the amount of the chromatic ink discharged from the succeeding nozzles is larger than the amount of the chromatic ink discharged from the preceding nozzles.