Liquid Ejection Head Substrate Crystal Diameter Gradient
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Solution Overview
Problem
The existing methods for maintaining the durability and gas barrier properties of cavitation resistance layers in liquid ejection heads, such as those using Ir, face issues with kogation deposition and layer thinning, leading to heating element breakage and reduced reliability.
Innovation Solution
A liquid ejection head substrate configuration with multiple layers, including a heating element, electric wiring, insulative layers, and a metal upper protection layer with varying crystal particle diameters to enhance adhesiveness and resistance, utilizing an electrochemical reaction to manage kogation deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the cavitation resistance layer is cleaned through electrochemical reaction to remove kogation, then the kogation accumulation is removed, but the film thickness of the cavitation resistance layer decreases gradually
Solution Approach 1:
The patent applies local quality by creating different crystal particle diameters in different regions of the cavitation resistance layer. The layer has a first average crystal particle diameter on the liquid-contact side and a second average crystal particle diameter on the third layer side, where these diameters are different. This local variation in crystal structure provides both effective kogation removal capability and enhanced gas barrier properties while maintaining adequate film thickness.
Solution Approach 2:
The patent employs composite material principles by forming the cavitation resistance layer with varying crystal particle diameters throughout its thickness. This creates a composite structure where different regions have different crystalline properties - the liquid-contact region has one crystal particle diameter optimized for electrochemical kogation removal, while the region near the third layer has a different crystal particle diameter optimized for gas barrier properties and mechanical strength.
2Object-generated harmful factors
If the film thickness of the cavitation resistance layer is decreased through repeated cleaning, then the kogation is removed more effectively, but the gas barrier property is reduced
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatial variation in crystal particle diameter. The region of the cavitation resistance layer that contacts the liquid has a first average crystal particle diameter optimized for electrochemical kogation removal, while the region adjacent to the third layer has a second average crystal particle diameter that provides superior gas barrier properties. This local differentiation allows each region to be optimized for its specific function without compromising the other.
Solution Approach 2:
The patent applies parameter changes by varying the crystal particle diameter parameter through the thickness of the cavitation resistance layer. Instead of using a uniform crystal structure, the patent creates a gradient or distribution of crystal particle sizes where the parameter (crystal particle diameter) changes from one region to another, enabling simultaneous optimization of both kogation removal and gas barrier functions.
3Productivity
If a massive amount of printing is performed to improve productivity, then the printing volume increases, but the cavitation resistance layer is subjected to increased physical and chemical action
Solution Approach 1:
The patent uses composite material principles with varying crystal particle diameters to create a cavitation resistance layer that can withstand the increased physical and chemical action from high-volume printing. The different crystal particle diameter regions provide a composite structure with enhanced overall durability, where the crystal structure distributes and resists the cumulative effects of cavitation, heat, and chemical exposure that occur during extensive printing operations.
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 configuration effectively suppresses the reduction in gas barrier properties, improving the durability and reliability of the liquid ejection head by maintaining the film thickness of the cavitation resistance layer and preventing heating element breakage.
Implementation Method 1
A current is applied from the electric wirings to the heating resistance element to heat the heating resistance element, and thus film boiling occurs in the liquid such as ink
Implementation Method 2
film boiling occurs in the liquid such as ink. Air bubbles generated in this process cause the ejection of the liquid from the ejection port
Implementation Method 3
a cleaning method in which the cavitation resistance layer is dissolved into the ink by using an electrochemical reaction that allows the cavitation resistance layer to act as an electrode, and thus the kogation accumulated on the cavitation resistance layer is removed
Implementation Method 4
the heat acting portion is subjected to physical action such as an impact from cavitation along with the bubbling or contraction of the liquid
Data Source
AI summary
An object is suppressing the reduction in the gas barrier property in a case where the cavitation resistance layer becomes thin. An embodiment of the present invention is a liquid ejection head substrate, including: a first layer that forms a heating element that generates heat energy to eject a liquid; a second layer that functions as an electric wiring connected with the heating element; a third layer that is insulative and covers the first layer and the second layer; and a fourth layer that is a layer arranged over the third layer so as to cover at least the heating element, formed of metal, and to generate an electrochemical reaction with the liquid, in which a first average crystal particle diameter on a side that is in contact with the liquid and a second average crystal particle diameter on a side of the third layer are different.