Liquid Ejection Head Pressure-Controlled Partition Space
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Solution Overview
Problem
Existing liquid ejection heads with laminated substrates face challenges in preventing the mixing of different liquids due to gaps and defects, leading to deterioration in recording image quality, as seen in ink jet recording heads where inks of different colors mix before ejection.
Innovation Solution
A liquid ejection head design featuring an ejection orifice, first and second flow passages penetrating the bonding surface between substrates, and an in-partition wall space with internal pressure lower than the liquids' pressures, which separates and contains any permeated liquid, preventing mixing by drawing it into the in-partition wall space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If substrates are laminated to form flow passages, then liquid ejection functionality is achieved, but gaps between substrates cause mixing of different liquids
Solution Approach 1:
A sealing material is introduced as an intermediary substance to fill gaps between laminated substrates. This sealing material acts as a mediator that prevents direct contact and mixing between different liquids flowing through adjacent flow passages, while allowing the substrates to remain laminated for manufacturing efficiency.
Solution Approach 2:
The sealing treatment is applied locally at the gaps between substrates rather than uniformly across the entire structure. This targeted approach maintains the overall laminated structure for flow passage formation while specifically addressing the separation issue at critical interface regions where gaps occur.
2Reliability
If sealing material is injected into separation groove, then liquid permeation is prevented, but aging deterioration of sealing material causes gap formation
Solution Approach 1:
The sealing material is pre-installed in the separation groove before the liquid ejection head is assembled and put into service. This beforehand cushioning ensures that gaps are sealed from the start, preventing liquid leakage and mixing. The design anticipates potential aging deterioration by providing this protective sealing layer that maintains separation even as other components age.
3Reliability
If partition wall separates flow passages, then liquid mixing is prevented, but defects in partition wall allow liquid permeation
Solution Approach 1:
The sealing material serves as an intermediary that compensates for imperfections in the partition wall structure. Rather than requiring perfectly precise partition wall manufacturing, the sealing material fills minor defects and gaps, ensuring liquid separation is maintained even when manufacturing precision is limited.
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
Effectively suppresses the mixing of different liquids, maintaining recording quality by ensuring that mixed liquids are not ejected, thus preventing the deterioration of image quality in ink jet recording devices.
Implementation Method 1
An internal pressure of the in-partition wall space is lower than any of pressures of the liquids in the first flow passage and the second flow passage
Data Source
AI summary
A liquid ejection head that includes ejection orifices and is configured by bonding a silicon substrate and a support substrate, flow passages which penetrate a bonding surface between the silicon substrate and the support substrate and through which different types of liquids flow. An in-partition wall space that is open to the bonding surface between the silicon substrate and the support substrate is formed in a partition wall for separating the flow passages. The internal pressure of the in-partition wall space is set to be lower than pressure of the liquid on each of the flow passages.