Inkjet Printhead Filter Segmentation for Debris and Bubble Management
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Solution Overview
Problem
Inkjet print heads face issues with debris and air bubbles entering the fluidic structures, which can disrupt droplet formation and block fluid flow, as filters can trap air bubbles and make it difficult to purge them, leading to potential blockages in the ink circulation path.
Innovation Solution
An inkjet print head design incorporating a filter with a specific filter surface arrangement and a manifold chamber to prevent debris from entering the droplet forming unit, where air bubbles can be easily removed through a purge action, ensuring continuous ink flow and preventing blockages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter is placed in the ink circulation path to prevent debris from entering fluidic structures, then debris protection is improved, but air bubbles are blocked and cannot be transported back to the ink reservoir, causing potential blockages
Solution Approach 1:
The filter is divided into two distinct surfaces: a first filter surface that forms part of the circulation path where debris is filtered, and a second filter surface that is not part of the circulation path. This segmentation allows air bubbles to pass through the filter without being trapped in the circulation path, resolving the contradiction between debris protection and air bubble transport reliability.
Solution Approach 2:
The second filter surface is extracted from the circulation path, creating a separate zone where air bubbles can accumulate and be purged independently. This extraction allows the filter to perform its debris-blocking function while simultaneously providing a dedicated pathway for air bubble removal, eliminating the trade-off between the two functions.
2Productivity
If very small fluidic structures are used to enable high-frequency operation and high resolution, then droplet ejection performance is improved, but small particles can enter and block the fluid flow or disrupt droplet formation
Solution Approach 1:
The filter is positioned upstream in the ink supply path, performing preliminary filtration of debris before the ink reaches the droplet forming unit. This preliminary action protects the small fluidic structures from particle contamination while allowing the system to maintain high-frequency operation and high resolution performance.
Solution Approach 2:
The filter acts as an intermediary component between the ink reservoir and the droplet forming unit. It mediates the ink flow by removing harmful particles while allowing legitimate ink flow to pass through, thereby protecting the vulnerable small fluidic structures without compromising the droplet ejection performance.
3Object-affected harmful factors
If a filter is used to prevent debris entry, then fluidic structure protection is improved, but the filter itself may become blocked by accumulated debris, disrupting ink flow
Solution Approach 1:
The filter design incorporates a dynamic purging mechanism where air bubbles can be actively removed through the second filter surface. This dynamic approach allows the filter to maintain its protective function while periodically clearing accumulated debris through purging actions, preventing filter blockage and ensuring continuous ink flow reliability.
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 solution effectively prevents debris from entering the fluidic structures and allows for efficient removal of air bubbles, maintaining the integrity of the ink flow and droplet formation process, reducing the need for extensive purging and minimizing the risk of blockages.
Implementation Method 1
a piezoelectric actuator being arranged in operative communication with the ink flow path for generating a pressure wave in the ink in the ink flow path
Implementation Method 2
a filter arranged between the ink supply substrate and the droplet forming unit. The filter has a first filter surface at an upstream side and a second filter surface at a downstream side, the second filter surface being opposite to the first filter surface and filter holes extending from the first filter surface to the second filter surface
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 2B~2C
AI summary
In an inkjet print head for generating a droplet of ink, the inkjet print head comprises an ink supply substrate having an ink supply channel in fluid communication with an ink supply connector channel for receiving ink from an ink reservoir and in fluid communication with an ink return connector channel for supplying ink to the ink reservoir; a droplet forming unit arranged on the ink supply substrate, the droplet forming unit having an ink inlet surface, in which ink inlet surface an ink inlet port for receiving ink from the ink supply substrate is arranged; a manifold chamber formed over the ink inlet surface of the droplet forming unit; and a filter arranged between the ink supply substrate and droplet forming unit, the filter having a first filter surface at an upstream side and a second filter surface at a downstream side, the second filter surface being opposite to the first filter surface and filter holes extending from the first filter surface to the second filter surface. The first filter surface forms a wall of the ink supply channel.