Inkjet Print Head Recirculation for Air Bubble Removal
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Solution Overview
Problem
Traditional methods for removing air bubbles from inkjet print heads result in waste ink, which becomes inefficient and costly due to increased power-down requirements from stringent energy savings, leading to unsatisfied customers.
Innovation Solution
The implementation of a recirculation system within the print head, where a pressure differential between upstream and downstream manifolds allows ink to flow through a half-etched recirculation channel, removing air bubbles without ejecting ink, and maintaining ink flow during non-jetting events, thus preventing ink waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional air removal approaches are used (transporting air bubbles to vent holes or forcing air through jetting elements), then air bubbles are removed from the print head, but ink is wasted through the vent holes or jetting elements
Solution Approach 1:
The ink delivery system is segmented into multiple separate channels: a primary channel for ink delivery to jetting elements and a separate recirculation channel for air bubble removal. This segmentation allows air bubbles to be removed through the recirculation channel without causing ink waste through vent holes or jetting elements, thus resolving the contradiction between effective air removal and ink conservation
Solution Approach 2:
A recirculation pump is introduced as an intermediary device that actively manages ink flow through the recirculation channel. The pump creates controlled circulation that facilitates air bubble removal while preventing uncontrolled ink ejection, thereby enabling reliable air removal without proportional ink waste
2Reliability
If purge cycles are increased to remove air introduced during frequent power-downs, then air bubble removal is improved, but ink waste increases
Solution Approach 1:
By segmenting the fluidic system into separate delivery and recirculation channels, the patent enables frequent purge cycles to be performed during power-up without increasing ink waste. Air bubbles are consistently removed through the recirculation channel while ink is protected from waste, allowing the system to tolerate more frequent power-down cycles
Solution Approach 2:
The recirculation channel provides continuous ink circulation during power-up phases, maintaining ink flow and preventing air bubble accumulation. This continuous action ensures that even with frequent power-downs, air bubbles are systematically removed without requiring excessive purge cycles that would waste ink
3Reliability
If ink flow is maintained during non-jetting events, then air bubble removal and ink circulation are improved, but system complexity increases
Solution Approach 1:
The patent employs hydraulic principles by using pressure differentials between the primary and recirculation channels to drive ink circulation during non-jetting events. This passive hydraulic approach maintains ink flow and facilitates air bubble removal without requiring complex active control systems, thus improving reliability while limiting complexity increase
Solution Approach 2:
The recirculation channel is designed to automatically circulate ink and remove air bubbles during non-jetting events without requiring external intervention or complex control mechanisms. The system self-regulates ink flow through pressure differentials, providing continuous air removal and ink circulation with minimal additional complexity
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 removes air bubbles without wasting ink, ensuring efficient print head performance and reducing user costs by maintaining ink flow and preventing ink settlement, thereby enhancing customer satisfaction.
Implementation Method 1
A negative pressure is applied to the first manifold and a lower negative pressure is applied to the second manifold for a predetermined amount of time prior to the jetting event
Data Source
AI summary
An inkjet print head including a plurality of single jet elements. Each of the single jet elements includes an aperture configured to eject ink during a jetting event, and a channel for receiving ink, the channeling including a recirculation portion configured to receive ink during a non-jetting event. The print head also includes a first manifold structured to supply ink to the channel, and a second manifold structured to receive ink from the recirculation portion of the channel. The ink flows from the inlet portion to the second outlet portion during non-jetting through the second outlet portion.