Liquid Ejection Head Segmentation for Undercoat Ink Mist
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Solution Overview
Problem
Liquid ejection heads face increased ink adhesion and mist issues when ejecting high volumes of ink for undercoat layers on non-white recording media, leading to reduced productivity due to self-induced jetting and ink mist accumulation.
Innovation Solution
The liquid ejection head is configured with distinct nozzle rows for undercoat-forming and image-forming liquids, where undercoat-forming liquid with larger pigment particles is ejected through a single nozzle row to minimize ink mist, and image-forming liquid with smaller particles is ejected through multiple nozzle rows to reduce self-induced jetting and maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ejection rate of undercoat-forming ink is increased to improve productivity, then the output per unit time increases, but ink mist occurrence increases leading to increased adhesion to nozzle surface
Solution Approach 1:
The patent divides the ejection system into separate head sections: a first head section dedicated to undercoat-forming ink ejection and a second head section for image-forming ink ejection. This segmentation allows independent optimization of each function, enabling high-speed undercoat application without compromising image quality or causing nozzle contamination from mixed ink types.
Solution Approach 2:
The patent applies different ink formulations with specific properties to different functional areas: undercoat-forming ink with larger pigment particles (≥200 nm) and higher concentration (≥7 mass%) is used in the first head section for high-speed coverage, while image-forming ink with smaller particles (<200 nm) and lower concentration (<7 mass%) is used in the second head section for quality image formation. Each head section is optimized for its specific purpose.
2Productivity
If multiple nozzle rows are used for undercoat-forming ink to increase ejection rate, then productivity improves, but self-induced jetting occurs causing ink mist
Solution Approach 1:
The patent segregates undercoat-forming ink ejection to a single nozzle row in the first head section, eliminating the self-induced jetting problem that occurs when multiple nozzle rows eject ink simultaneously. This single-nozzle-row approach prevents the aerodynamic interference between adjacent jets that causes mist formation, while still achieving high productivity through optimized ejection parameters.
3Productivity
If undercoat-forming ink with high pigment concentration is used to form solid block undercoat, then coverage and productivity improve, but ink mist and adhesion increase
Solution Approach 1:
The patent creates a dedicated first head section for undercoat-forming ink with high pigment concentration (≥7 mass%) and larger particles (≥200 nm). This segmentation isolates the high-concentration ink ejection from the image-forming process, allowing the use of opaque, high-coverage ink formulations without causing nozzle contamination that would affect subsequent image formation.
Solution Approach 2:
The patent optimizes ink properties locally for the undercoat function: undercoat-forming ink uses larger pigment particles (≥200 nm) and higher concentration (≥7 mass%) to achieve solid block coverage and opacity on non-white substrates, while this formulation is confined to the first head section where it serves its coverage function without interfering with the precision image formation in the second head section.
Data Source
AI summary
A liquid ejection head configured to eject a liquid through nozzles includes plural head sections including a first head section and a second head section. Each of the plurality of head sections includes plural nozzle rows. One of the plural nozzle rows of the first head section is supplied with an undercoat-forming liquid containing an undercoat-forming pigment with an average particle diameter of at least 200 nm at a concentration of at least 7 percent by mass. Each of the plural nozzle rows of the second head section is supplied with an image-forming liquid containing an image-forming pigment with an average particle diameter of less than 200 nm at a concentration of less than 7 percent by mass.