Droplet Ejection Head Unit Seam Shift for Uniform Panel Printing
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Solution Overview
Problem
Droplet ejection apparatuses face issues with color heterogeneity and streaks in image display panels due to variations in ejection amounts and nozzle pitch errors, leading to diminished image quality.
Innovation Solution
A head unit with multiple droplet ejection heads arranged in a specific configuration to overlap nozzle arrays, allowing for average ejection amounts and shifted seams to prevent color heterogeneity and disperse streaks, ensuring uniform material distribution and enlarged ejection width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple droplet ejection heads are arranged to extend the ejection width, then the coverage area is improved, but color heterogeneity occurs due to variations in ejection amounts among different heads
Solution Approach 1:
The head unit is divided into multiple droplet ejection heads (first, second, third, and fourth heads) with separate nozzle arrays. Each head operates independently but contributes to the same ejection region, allowing individual ejection amount variations to be averaged out and reducing color heterogeneity while maintaining extended coverage width
Solution Approach 2:
The patent changes the arrangement parameter of the nozzle arrays by shifting the second and fourth nozzle arrays relative to the first and third arrays. This parameter change ensures that seams between adjacent nozzle arrays are offset, preventing streak formation while maintaining uniform material distribution across the extended ejection width
2Length of stationary object
If droplet ejection heads are arranged in a linear sequence, then the ejection width is extended, but streaks are generated at the seams between adjacent nozzle arrays
Solution Approach 1:
The patent introduces asymmetric positioning of the nozzle arrays by shifting the second and fourth arrays relative to the first and third arrays. This asymmetric arrangement offsets the seams between adjacent nozzle arrays, preventing streak formation while maintaining the extended ejection width
Solution Approach 2:
The patent resolves the streak problem by introducing a dimensional offset in the vertical direction (second direction perpendicular to the scanning direction). By shifting nozzle arrays in this additional dimension, the seams are dispersed and prevented from aligning, eliminating streak formation while preserving horizontal ejection width
Data Source
AI summary
A head unit 103 for use in a droplet ejection apparatus is provided with a plurality of droplet ejection heads for ejecting one or more kind of liquid material of a predetermined color onto a base in the form of droplets. Each of the droplet ejection heads includes at least one nozzle array constituted from a plurality of nozzles linearly aligned. The liquid material is adapted to be ejected through the plurality of nozzles of the plurality of droplet ejection heads in the form of droplets. The plurality of droplet ejection heads include at least two sets of two adjacent droplet ejection heads which are arranged in a consecutive manner in a first direction parallel to each of the nozzle arrays. The two adjacent nozzle arrays of each of the at least two sets of two adjacent droplet ejection heads are arranged so that the nozzles thereof are consecutive via a seam between the two adjacent nozzle arrays of the two adjacent droplet ejection heads when viewed from a second direction perpendicular to the first direction. The at least two sets of two adjacent droplet ejection heads for ejecting the droplets of the liquid material of the same color are arranged so that all the seams thereof are shifted with respect to each other in the first direction when viewed from the second direction.