Dual Circulation Printhead for Uniform Droplet Ejection
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Solution Overview
Problem
Fluid ejection devices face challenges in achieving uniform droplet size and direction due to pressure disturbances and contamination issues, which affect the consistency and efficiency of fluid deposition on a medium.
Innovation Solution
A printhead system with a substrate and dual fluid circulation paths, where one path is parallel and has a larger cross-sectional area, and a temperature control mechanism, allowing for simultaneous fluid flow through the substrate and a separate recirculation path without direct pumping, to maintain consistent fluid temperature and remove contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single fluid circulation path through the substrate is used, then the structure is simple, but pressure disturbances and contamination affect droplet uniformity
Solution Approach 1:
The single circulation path is segmented into two separate paths: a first circulation path through the substrate and a second circulation path through the printhead body. This segmentation allows the second path to handle bulk fluid circulation and temperature control while the first path maintains stable pressure for droplet ejection, thereby improving droplet uniformity without excessive complexity
Solution Approach 2:
The second circulation path acts as an intermediary that handles the bulk fluid flow and temperature control functions, isolating the substrate and droplet ejection process from direct pressure disturbances. This intermediary path absorbs pressure fluctuations and provides stable thermal conditions, improving droplet consistency
2Manufacturing precision
If direct pumping through the substrate is used, then fluid flow is controlled, but pressure disturbances affect droplet ejection uniformity
Solution Approach 1:
The pumping function is segmented from the droplet ejection function. The pump drives fluid through the second circulation path in the printhead body, while the substrate receives fluid through a separate first circulation path. This segmentation isolates the substrate from pump-induced pressure disturbances, ensuring stable droplet ejection while maintaining controlled fluid flow
Solution Approach 2:
The pump and its associated pressure disturbances are extracted from the substrate system and placed in the printhead body through the second circulation path. This extraction removes the source of pressure instability from the droplet ejection process, improving both droplet consistency and pressure stability
3Temperature
If no separate recirculation path is used, then the device is simpler, but temperature control and contaminant removal are insufficient
Solution Approach 1:
The second circulation path serves multiple functions simultaneously: it provides bulk fluid circulation, temperature control through thermal contact with the substrate, and contaminant removal via the filter. This multi-functionality achieves improved temperature consistency without proportionally increasing device complexity
Solution Approach 2:
The second circulation path acts as a thermal intermediary between the fluid supply and the substrate. It provides stable thermal conditions to the substrate through controlled fluid circulation, improving temperature consistency while isolating the substrate from direct pump pressure disturbances
4Loss of energy
If the second circulation path has larger cross-sectional area, then fluid flow resistance is reduced, but the path occupies more space
Solution Approach 1:
The circulation paths have different cross-sectional areas optimized for their specific functions. The second circulation path has a larger cross-sectional area to minimize flow resistance for bulk fluid circulation, while the first circulation path through the substrate has a smaller area appropriate for controlled droplet supply. This local optimization reduces overall energy loss without excessive volume increase
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 configuration ensures uniform fluid droplet ejection by controlling temperature and removing air bubbles and contaminants, resulting in consistent printing and reducing waste from warm-up runs.
Implementation Method 1
A temperature sensor and/or a temperature control device can be in thermal communication with one or both of the first circulation path and the second circulation path
Implementation Method 2
A filter can be positioned in the first circulation path, the second circulation path, or both
Data Source
AI summary
A fluid droplet ejection apparatus includes a printhead having a fluid supply and a fluid return. A substrate is attached to the printhead, and the substrate includes a fluid inlet and a fluid outlet on a surface of the substrate proximate to the fluid supply and fluid return. Nozzles are in fluid communication with the fluid inlet. The fluid inlet of the substrate is in fluid communication with the fluid supply, and the fluid outlet is in fluid communication with the fluid return. A first circulation path through the substrate is between the fluid inlet and the fluid outlet. The fluid supply is in fluid communication with the fluid return through a second circulation path that is through the printhead and not through the substrate.