Liquid Ejection Head Counter Electrode for Uniform Kogation Removal
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Solution Overview
Problem
In liquid ejection heads, kogation on the heat acting portion causes uneven heat conduction, leading to unstable ejection performance due to uneven dissolution of the upper protective layer during electrochemical reactions.
Innovation Solution
The configuration involves a counter electrode positioned to minimize the distance difference between the upper protective layer and the counter electrode, ensuring a ratio of 1<a/b≦2, which uniformizes the film thickness reduction during kogation removal, thereby maintaining consistent heat conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper protective layer is used as an anode for electrochemical reaction to remove kogation, then kogation removal is achieved, but uneven film thickness reduction occurs causing unstable ejection
Solution Approach 1:
The patent applies local quality by creating different functional zones in the liquid ejection head structure. Specifically, the heating section has a first thickness and the non-heating section has a second thickness different from the first, allowing localized control of film thickness to achieve uniform electrochemical reaction across the anode surface while maintaining different functional requirements in different regions
Solution Approach 2:
The patent changes the thickness parameter of the upper protective layer across different sections. By setting the first thickness in the heating section and the second thickness in the non-heating section such that their ratio falls within a specific range, the patent optimizes the electrochemical reaction uniformity and prevents uneven film reduction during kogation removal
2Reliability
If parallel electrode arrangement is used for electrochemical reaction, then kogation removal is enabled, but uneven voltage distribution occurs leading to inconsistent heat conduction
Solution Approach 1:
The patent employs asymmetric electrode arrangement where the cathode is positioned offset from the anode rather than in direct parallel alignment. The offset distance is specifically controlled to be within a certain range, creating an asymmetric field distribution that ensures uniform voltage application across the electrochemical reaction area, thereby achieving consistent heat conduction after kogation removal
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 ensures uniform film thickness reduction and stable liquid ejection performance by maintaining consistent heat conduction across the heat acting portion.
Implementation Method 1
a heating section, a protective film provided above the heating section, an electrode capable of generating a voltage between the protective film and the electrode; and an ejection port, so as to eject liquid from the ejection port with use of heat generated by the heating section via the protective film
Implementation Method 2
providing an area which includes a heat acting portion with an upper protective layer acting as an electrode for generating an electrochemical reaction with ink, allowing the surface of the upper protective layer to be eluted, and removing kogation on the heat acting portion
Data Source
AI summary
In a liquid ejection head for ejecting liquid by using thermal energy, reduction of film thickness caused by elution of a protective layer when kogation on the protective layer is removed is made uniform and decrease in liquid ejection performance is suppressed. More specifically, a counter electrode is provided around a portion on which an ejection port of a flow path forming member is formed.