Printhead Air Removal via Semi-Permeable Membrane
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Solution Overview
Problem
Air bubbles in the print fluid can negatively affect the jetting characteristics of printheads, leading to inconsistent droplet formation and lower print quality, especially in high-productivity Drop on Demand printing applications.
Innovation Solution
A printhead design incorporating a semi-permeable membrane between the supply manifold and a cavity, allowing air to escape while keeping the print fluid contained, with the option of applying a vacuum to assist in air removal, ensuring consistent droplet formation and higher print quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air bubbles are present in the print fluid, then the printhead can operate continuously, but the jetting characteristics deteriorate and print quality decreases
Solution Approach 1:
The patent employs a porous membrane (e.g., PTFE membrane with 0.03 micrometer pores) that allows air bubbles to pass through while blocking liquid print fluid. The membrane is positioned in the fluid path where air bubbles naturally accumulate, enabling selective removal of gas phases without losing liquid material, thus maintaining jetting precision while allowing continuous operation.
2Manufacturing precision
If a semi-permeable membrane is added to remove air, then air bubbles are eliminated and droplet formation improves, but the device structure becomes more complex
Solution Approach 1:
The patent integrates the air removal function directly into the existing printhead structure by incorporating the porous membrane into the fluid pathway architecture. The membrane is positioned at strategic locations where air bubbles naturally accumulate, merging the air removal function with the existing fluid delivery system rather than adding separate external components.
3Manufacturing precision
If vacuum is applied to enhance air removal, then air evacuation is improved and print quality increases, but energy consumption increases
Solution Approach 1:
The patent applies vacuum pressure during the priming and initialization phase of printhead operation to proactively remove air bubbles from the fluid pathway before normal printing begins. Once the system is primed and air-free, the vacuum can be discontinued or reduced, allowing the printhead to operate in normal mode without continuous energy-consuming vacuum application, thus achieving air removal efficiency while minimizing ongoing energy consumption.
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 air removal mechanism enhances the reliability and consistency of droplet ejection, resulting in improved print quality by eliminating air bubbles and stabilizing pressure waves during jetting operations.
Implementation Method 1
a semi-permeable membrane disposed between the cavity and the supply manifold
Implementation Method 2
A vacuum may be applied to the cavity to assist in drawing the air from the print fluid and through the semi-permeable membrane
Data Source
AI summary
Printheads for jetting a print fluid. In one embodiment, a printhead comprises a main body configured to attach to a stack of plates, where the stack of plates forms a row of jetting channels configured to jet droplets of a print fluid. The main body includes a supply manifold configured to provide a fluid path for the print fluid to the row of jetting channels, a cavity, and a semi-permeable membrane disposed between the cavity and the supply manifold.