Wicking Separator for Ink Jet Bubble Removal
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Solution Overview
Problem
Ink jet printers face issues with bubbles in the ink causing misplaced, intermittent, or weak ink jetting due to existing filtration and separation methods, which can lead to clogged filters, pressure drops, and increased complexity, especially with solid ink printers experiencing freeze-melt cycles.
Innovation Solution
The use of wicking features in a separator element within the ink jet print head to separate bubbles from ink through capillary action, where the ink moves through wicking features and vapor is directed to a separate path, utilizing a layered structure with specific dimensions and geometries to control hydrodynamic resistances and pressure gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional filtration methods are used to remove bubbles from ink, then bubble removal is achieved, but filter clogging and pressure drops occur
Solution Approach 1:
The separator element divides the ink flow path into distinct regions: a wicking region with capillary channels for bubble-free ink transport, and a non-wicking region for vapor bubble collection and removal. This segmentation allows bubbles to be separated from ink without blocking the entire flow path, maintaining ink flow rate while achieving effective bubble removal.
Solution Approach 2:
The wicking material acts as an intermediary between the ink containing bubbles and the bubble-free ink output. It selectively absorbs ink while excluding vapor bubbles, allowing the ink to pass through capillary channels without bubbles, thus removing bubbles without causing filter clogging or pressure drops.
2Reliability
If larger separator elements are used to improve bubble separation, then separation effectiveness increases, but print head bulk increases
Solution Approach 1:
The separator element uses localized wicking regions with specific capillary dimensions optimized for bubble exclusion, rather than uniformly large structures. The wicking material is positioned only where needed at the ink jet orifices, providing effective bubble separation in a compact, localized manner that minimizes print head bulk.
3Reliability
If wicking features with small radius of curvature are used to exclude bubbles, then bubble exclusion improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention uses porous wicking material with inherent capillary structures that provide the necessary small radius of curvature for bubble exclusion. The porous nature of the material naturally creates the required capillary channels without requiring precise machining of individual features, thereby achieving effective bubble exclusion while reducing manufacturing precision requirements.
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 approach effectively reduces bubble presence in the ink, preventing clogging and pressure drops, while maintaining efficient ink flow and reducing the bulk of the print head, resulting in improved print quality and reliability.
Implementation Method 1
The wicking features are dimensioned to allow the ink to move through the wicking features by capillary action
Implementation Method 2
Each ink outlet is dimensioned so that a pressure gradient required for entry of the bubbles into the ink outlet is greater than a pressure gradient required for entry of the bubbles into the vapor outlet
Data Source
AI summary
Approaches to remove bubbles from ink in an ink jet printer are described. Bubble removal may be implemented using one or more separator elements configured to separate bubbles of a vapor from ink. Each separator element includes wicking features having dimensions sufficient to allow capillary movement of the ink in the wicking features and to substantially exclude the bubbles from the wicking features. One or more inlets allow passage of the ink that includes the bubbles into the separator element. At least one vapor outlet allows vapor that has been separated from the ink to exit from the separator element. The ink exits from the separator element thought one or more ink outlets.