Inkjet Head Dot Overlap Control for Gloss Banding
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Solution Overview
Problem
Existing image forming methods using ink with pigments suffer from non-uniform gloss in screen tint images due to the discreteness and discontinuity of dot arrangements, leading to degraded image quality and gloss banding.
Innovation Solution
An image forming apparatus and method that adjusts the overlap rate of similar color dots on a recording medium, with a higher overlap rate in high density gradation ranges and a lower rate in low density gradation ranges, using an image processing unit to control the dot formation process, thereby managing surface smoothness and reducing gloss banding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dots of similar colors are formed to be overlapped at the same position at a high rate, then surface smoothness is improved and gloss banding is suppressed, but noise and graininess increase in low density gradation ranges
Solution Approach 1:
The patent applies local quality by differentiating the dot overlap rate based on density gradation ranges. In low density gradation ranges, dots of similar colors are formed to be overlapped at a lower rate to prevent noise and graininess. In high density gradation ranges, dots are overlapped at a higher rate to suppress gloss banding and improve surface smoothness. This spatial differentiation of dot arrangement parameters resolves the contradiction between surface smoothness and noise prevention.
2Stability of the object's composition
If dots are arranged with regular spacing, then image structure is maintained, but gloss banding occurs due to transport accuracy variations and pigment physicality
Solution Approach 1:
The patent introduces dynamics by making the dot arrangement pattern adaptive rather than static. The image processing unit dynamically adjusts dot positions and overlap rates based on density gradation ranges and similar color relationships. This dynamic adjustment compensates for transport accuracy variations and pigment physicality effects, maintaining image structure while preventing gloss banding through controlled irregularities in dot placement.
3Manufacturing precision
If the overlap rate of similar color dots is increased uniformly across all density ranges, then gloss banding is suppressed, but noise and graininess increase significantly in low density areas
Solution Approach 1:
The patent applies parameter changes by varying the dot overlap rate parameter according to density gradation ranges. The image processing unit changes the overlap rate parameter from lower values in low density ranges to higher values in high density ranges. This parameter adaptation resolves the contradiction between gloss uniformity and noise prevention by optimizing the overlap rate for each specific density context.
Data Source
AI summary
An image forming apparatus configured to form a plurality of dots on a recording medium by ejecting ink droplets includes: a recording head configured to eject the ink droplets of a plurality of colors including similar colors, which are colors of which densities or hues are equal to each other; a transporting unit configured to relatively move the recording head and the recording medium; a head driving circuit configured to perform a driving control of the recording head based on a control signal; and an image processing unit configured to convert an input image signal into a control signal to be supplied to the head driving circuit in a manner so that the dots of the similar colors are formed to be overlapped at a same position at a lower rate in a low density gradation range and at a higher rate in a high density gradation range.