Inkjet Nozzle Arrangement for UV Curing Gloss Uniformity
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Solution Overview
Problem
Conventional inkjet recording apparatuses using UV curing inks face issues with uneven glossiness due to landing interference and varying cure sensitivity among different colors, which are not adequately addressed by existing nozzle arrangement and light source control methods.
Innovation Solution
The apparatus features nozzle rows with nozzles arranged to be shifted by a specific pitch in the sub-scanning direction, with the ink having the lowest cure sensitivity positioned most upstream and light inks placed between thick inks, while using separated light sources for semi-curing and main curing to optimize ink deposition and curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light amount of the semi-curing light source is reduced to increase glossiness, then glossiness is improved, but landing interference between ink droplets of different colors increases causing periodic uneven glossiness
Solution Approach 1:
The patent applies preliminary action by arranging nozzles to be shifted by P/N in the sub-scanning direction and ordering them by cure sensitivity before the printing process begins. This pre-arrangement ensures that inks with lower cure sensitivity are deposited first on layers closer to the recording surface, preventing landing interference before it occurs and enabling reduced semi-curing light amount while maintaining uniform glossiness.
Solution Approach 2:
The patent changes the parameter of nozzle arrangement by shifting nozzles by P/N pitch and ordering them according to cure sensitivity. This parameter change in the physical arrangement and sequencing of nozzles allows the system to achieve both high glossiness (through reduced semi-curing light) and uniformity (through prevented landing interference).
2Device complexity
If nozzles of respective color heads are arrayed on the same line in main scanning direction to share arrangement positions, then device complexity is reduced, but landing interference occurs causing line-like surface shapes with large depressions and projections
Solution Approach 1:
The patent resolves the contradiction by introducing a shift in the sub-scanning direction (orthogonal to the main scanning direction) while maintaining the same-line arrangement in the main scanning direction. This dimensional adjustment of P/N pitch creates offset deposition positions that eliminate line-like surface defects while preserving the simplified same-line nozzle configuration.
Solution Approach 2:
The patent applies local quality by creating localized offset positions for different color nozzles through the P/N pitch shift in the sub-scanning direction. Each nozzle deposits ink at a slightly different local position, preventing the formation of uniform line-like patterns while maintaining overall arrangement simplicity.
3Productivity
If UV curing inks are used with nozzles arrayed on the same line, then productivity is improved by one main scanning action, but uneven glossiness occurs due to different cure sensitivities of respective colors
Solution Approach 1:
The patent applies preliminary action by pre-arranging nozzles in order of cure sensitivity and shifting them by P/N pitch before the printing process. This ensures that inks with lower cure sensitivity (such as yellow and cyan) are deposited first on layers closer to the recording surface, allowing them to be cured more effectively while maintaining uniform glossiness across all colors during single-pass printing.
Solution Approach 2:
The patent changes the parameter of nozzle arrangement by introducing a P/N pitch shift in the sub-scanning direction and ordering nozzles by cure sensitivity. This parameter change enables differentiated curing control for each color while maintaining high productivity through single-pass printing with unified light sources.
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 arrangement reduces landing interference and uneven glossiness, allowing for high-quality image formation with improved surface stability and glossiness, while minimizing the light amount of the semi-curing source to prevent interference.
Implementation Method 1
nozzles each of which ejects curable inks cured by imparted activation energy
Implementation Method 2
separated light sources for semi-curing and main curing
Data Source
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AI summary
In an inkjet head (24, 110) which has nozzle rows having nozzles each of which ejects curable inks cured by imparted activation energy and which are arranged in a first direction at a pitch P, the nozzle rows being N (N≥5) nozzle rows of every color which eject, respectively, thick inks of four colors including cyan, magenta, yellow and black, and at least one light ink among light inks similar in color tone to the thick inks, the nozzles in each of the nozzle rows are arranged so as to be shifted by P/N from each other in a first direction, a nozzle of an ink with lowest cure sensitivity is arranged on the most upstream side in a direction of relative movement of a recording medium (12, 120) in the first direction, and further the nozzle of light ink is arranged in between the nozzles of two different thick inks.