Photocurable Ink Dot Merging Control for Fringe Elimination
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Solution Overview
Problem
In printing apparatuses using photocurable ink, variations in the time from ink droplet ejection to curing between forward and backward scans result in uneven dot merging, leading to fringes and degraded print quality due to differences in dot shape and surface reflections.
Innovation Solution
A printing method and apparatus that alternately apply light in forward and backward directions, using a combination of large and small ink droplets, with controlled ejection to ensure dots are not in contact during subsequent scans, maintaining uniform surface protrusions and depressions across the print image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the carriage reciprocates to perform scans in units of passes, then printing is performed by a plurality of passes, but the time from ejection of ink droplets to curing by light differs between forward scan and backward scan, causing variations in dot merging and fringes
Solution Approach 1:
The patent applies local quality by differentiating the treatment of forward and backward scans. Specifically, light radiation is applied to the backward scan portion after a delay period following ink droplet ejection, while the forward scan portion receives light radiation immediately. This localized temporal differentiation compensates for the distance-based time variations between scans, ensuring uniform dot merging and eliminating fringes across the entire print image.
2Shape
If light is applied early after ink droplet ejection, then the degree of merging of adjacent ink droplets is low, but dots have protrusions and depressions; if light is applied later, then the degree of merging is higher, but dots become almost flat
Solution Approach 1:
The patent applies preliminary action by introducing a delay period before applying light radiation to the backward scan portion. This delay allows ink droplets to land and begin merging on the recording medium before curing, ensuring that adjacent droplets merge to form uniform dots with consistent surface texture. The preliminary landing and merging phase eliminates the protrusions and depressions that would otherwise occur if light were applied immediately.
3Device complexity
If the distance between the head and light source varies in forward and backward scans, then the time from ejection to curing differs, but this causes fringes and degraded print quality
Solution Approach 1:
The patent applies feedback by implementing a control mechanism that compensates for the varying time from ejection to curing based on the scan direction. The system detects whether the carriage is performing a forward or backward scan and adjusts the light radiation timing accordingly. This feedback-based timing adjustment ensures that all ink droplets, regardless of their position on the carriage, receive light radiation at the optimal moment to achieve uniform merging and eliminate fringes.
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 eliminates fringes by maintaining uniform surface texture, enhancing print quality without affecting color density or increasing the number of printing passes, thus improving the overall image quality.
Implementation Method 1
a photocurable ink that is cured when irradiated with light such as ultraviolet rays
Data Source
AI summary
A printing method and a printing apparatus are provided. After ink droplets of a photocurable ink are landed on a print medium, a scan of applying a light to cure the ink droplets to form dots is performed alternately in a forward direction and a backward direction with respect to a predetermined unit region, and a time from landing to curing of the ink droplets onto the print medium differs between the forward direction and the backward direction. The printing method includes: providing the ink droplets that include: a large dot having a large amount of ink per droplet, and a small dot having a smaller amount of ink per droplet than that of the large dot; and controlling ejection of the ink droplets, such that number of passes when forming the large dot is greater than number of passes when forming the small dot, when forming a print image.