Liquid Ejection Head With Bidirectional Ink Circulation
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Solution Overview
Problem
Existing liquid ejection heads face issues with ejection stability due to one-directional ink circulation, leading to decreased ink supply to ejection ports and potential thickening of ink, which affects printing quality.
Innovation Solution
A liquid ejection head design incorporating a circulation system with a circulation pump and dual pressure adjustment units within the head, allowing bidirectional ink flow and maintaining stable ink pressure through a network of channels and valves, ensuring consistent ink supply to ejection ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-directional circulation system with a check valve is used, then the circulation pump structure is simple, but the ink supply to ejection ports decreases and ejection stability is lowered
Solution Approach 1:
The patent applies the dynamics principle by enabling the circulation pump to operate in both forward and reverse directions. The pump controller switches the pump operation between forward circulation mode and reverse circulation mode, allowing the ink to flow bidirectionally through the circulation channel. This dynamic operation ensures that ink is supplied to ejection ports from both the forward circulation path and the reverse circulation path, maintaining stable ejection while preventing ink depletion in any single direction.
2Device complexity
If one-directional ink circulation is used, then the circulation system is simple, but ink thickening occurs and printing quality deteriorates
Solution Approach 1:
The patent applies the continuity of useful action principle by implementing continuous bidirectional circulation of ink. The circulation system alternates between forward circulation and reverse circulation, ensuring that ink is continuously moved through the ejection ports from both directions. This continuous action prevents ink from stagnating in any one location, thereby preventing thickening and maintaining consistent printing quality over time.
3Reliability
If bidirectional circulation is implemented, then ejection stability is improved, but the circulation pump control complexity increases
Solution Approach 1:
The patent applies the feedback principle through the pump controller that monitors and controls the pump operation modes. The controller switches between forward and reverse circulation modes based on the operational requirements, effectively using feedback control to maintain stable ejection. The controller manages the bidirectional circulation by detecting the current state and adjusting the pump operation accordingly, thereby achieving ejection stability while keeping the control system manageable.
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 maintains ejection stability and prevents ink thickening, enhancing printing quality by ensuring consistent ink flow and reducing the apparatus size and cost through simplified tube connections.
Implementation Method 1
a piezoelectric circulation pump is mounted in a liquid ejection head to circulate an ink inside the liquid ejection head
Implementation Method 2
the circulation pump, which circulates the ink, is equipped with a check valve and the configuration is therefore such that the ink is circulated only in one direction through the circulation channel
Implementation Method 3
the ink supplied to a pressure control mechanism from the circulation pump is then supplied to pressure chambers through ink supply channels
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A liquid ejection head (1) includes a pressure chamber (12), an upstream channel (130), a downstream channel (140), a pump (500), an inflow channel (110, 121), and a bypass channel (160). The upstream channel communicates with the pressure chamber to supply the liquid to the pressure chamber. The downstream channel communicates with the pressure chamber. The pump communicates with the upstream channel and the downstream channel to cause the liquid in the downstream channel to flow into the upstream channel. The inflow channel communicates with the upstream channel to cause the liquid to be supplied to the pressure chamber to flow into the upstream channel. The upstream channel and the downstream channel communicate with each other through the bypass channel without the pressure chamber being between the upstream channel and the downstream channel. Part of the liquid flowing from the upstream channel into the bypass channel flows into the pressure chamber through the downstream channel.