Inkjet Printing Head Pack Alternating Droplet Volume
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Solution Overview
Problem
Existing inkjet printing technologies for display devices, particularly OLED displays, face challenges in maintaining consistent droplet volume, leading to line stains and reduced display quality due to periodic repeatability of droplet volume.
Innovation Solution
The inkjet printing apparatus employs a head pack with multiple heads, each with nozzles that eject droplets of alternating volumes (+1.5% and -1.5% of a reference volume, ensuring non-overlapping nozzle arrangements and adjustable voltage for each head to achieve different droplet volumes, thereby reducing line stains and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If droplet volume is kept consistent across all nozzles, then manufacturing precision is maintained, but line stains occur due to periodic repeatability issues
Solution Approach 1:
The patent applies local quality by assigning different droplet volumes to different nozzle groups (first group: +1.5% deviation, second group: -1.5% deviation) rather than uniform volumes. This localized variation in droplet volume characteristics prevents periodic repeatability issues that cause line stains, while maintaining overall manufacturing precision through controlled deviation patterns.
Solution Approach 2:
The patent implements asymmetry by intentionally creating asymmetric droplet volume distributions between adjacent nozzle groups. Instead of symmetric equal volumes, the first nozzle group ejects droplets with +1.5% volume deviation while the second nozzle group ejects droplets with -1.5% volume deviation, breaking the periodic symmetry that causes line stains.
2Object-affected harmful factors
If multiple heads with different droplet volumes are used, then line stains are reduced, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the head pack into multiple independent head units (first head, second head, third head) where each head contains nozzle groups with specific droplet volume characteristics. This segmentation allows different droplet volume patterns to be applied to different regions, reducing line stains while managing complexity through modular head design.
Solution Approach 2:
The patent uses periodic action by arranging heads and nozzle groups in alternating patterns (first head with +1.5% deviation, second head with -1.5% deviation, third head with +1.5% deviation) along the second direction. This periodic alternation of droplet volumes compensates for cumulative errors and prevents line stains without requiring complex non-periodic configurations.
Data Source
AI summary
An inkjet printing apparatus includes a head pack including a plurality of heads, wherein each of the plurality of heads includes a plurality of nozzles, wherein each of the plurality of heads extends in a first direction and is disposed adjacent to each other in a second direction intersecting the first direction, and a volume of a droplet ejected from each of the plurality of nozzles is alternately set to a first volume larger than a reference volume and a second volume smaller than the reference volume for each of the plurality of heads along the second direction.