Line-Head Inkjet Recording for Color Streak Reduction
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Solution Overview
Problem
Recording methods using a line head in ink jet recording apparatuses face issues with color unevenness and color difference streaks due to varying inter-nozzle distances, leading to unsatisfactory color developability in high-speed printing.
Innovation Solution
A recording method employing a line head with a first ink containing an azo-based pigment for red-based ink and a second chromatic ink, both aqueous, arranged to vary landing times on the recording medium, and using specific pigment compositions and additives to enhance color developability and reduce streaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a line head with fixed nozzle arrangement is used for high-speed printing, then productivity is improved, but color unevenness and color difference streaks occur due to varying inter-nozzle distances
Solution Approach 1:
The patent applies the dynamics principle by making the inter-nozzle distance variable rather than fixed. The line head is designed with different inter-nozzle distances in different regions (first region with first inter-nozzle distance, second region with second inter-nozzle distance) to dynamically adapt to the varying landing time differences that occur during high-speed printing. This dynamic adjustment of nozzle spacing compensates for the time differences in ink landing on the recording medium, thereby maintaining color uniformity while enabling high-speed operation.
Solution Approach 2:
The patent applies the local quality principle by assigning different inter-nozzle distances to different regions of the line head. Specifically, nozzles in the first region have a first inter-nozzle distance while nozzles in the second region have a second inter-nozzle distance. This local differentiation allows each region to be optimized for its specific printing conditions, with the nozzle spacing tailored to compensate for local variations in landing time, thus achieving overall color uniformity across the entire printed area.
2Device complexity
If conventional ink compositions are used with varying landing times, then device complexity is reduced, but color developability deteriorates due to color difference streaks
Solution Approach 1:
The patent applies the parameter changes principle by modifying the physical parameters of the ink composition. The ink is formulated with specific components including a solvent mixture (water, alcohol, and glycol in controlled proportions), surfactants, and thickening agents to achieve a balanced viscosity and surface tension. These parameter adjustments ensure that the ink maintains consistent flow characteristics and landing behavior even when landing times vary across different regions of the line head, thereby improving color developability without increasing device complexity.
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
The method effectively reduces color difference streaks and enhances color developability in high-speed printing by optimizing ink composition and nozzle arrangement, resulting in improved image quality.
Implementation Method 1
an ink composition including a first ink and a second ink is used. In the line head, a plurality of first nozzles ejecting the first ink is arranged in the direction intersecting the transport direction, and a plurality of second nozzles ejecting the second ink is arranged in the direction intersecting the transport direction
Data Source
AI summary
A recording method includes: a transporting step of transporting a recording medium; and an ink deposition step of ejecting an ink composition from an ink jet head to deposit the ink composition onto the recording medium transported in the transporting step, in which the ink jet head is a line head having a length equal to or longer than a recording region of the recording medium in a direction intersecting the transport direction; the ink composition includes a first ink that contains an azo-based pigment and is a red-based ink, and a second ink that contains a pigment and is a chromatic ink other than the red-based ink; each of the first ink and the second ink is an aqueous ink; in the line head, multiple first nozzles ejecting the first ink are arranged in the direction intersecting the transport direction, and multiple second nozzles ejecting the second ink are arranged in the direction intersecting the transport direction; the line head has a portion in which a time difference between landing of the first ink and landing of the second ink on the recording medium varies between portions of the line head in the direction intersecting the transport direction; and at least one of the first ink and the second ink has a thickening ratio of less than 2.0 when the ink is mixed with an aqueous calcium propionate solution having a Ca concentration of 0.3 mol/L at a mass ratio of 10:1.