Liquid Ejection Head Cleaning via Electrochemical Coating Elution
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Solution Overview
Problem
Existing cleaning methods for liquid ejection heads, such as those described in Japanese Patent Laid-Open No. 2008-105364, require complex sequences and significant time to remove kogation, necessitating liquid suction and pressurization, which are inefficient and require large amounts of liquid.
Innovation Solution
A method involving the application of a voltage to a coating layer on the heat generating resistive element to induce an electrochemical reaction, causing the coating layer to be eluted into the liquid and removing kogation, while simultaneously generating heat to eliminate air bubbles and maintain electrochemical reaction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If liquid suction and pressurization are used to remove air bubbles during electrochemical cleaning, then air bubbles are eliminated from the upper protective layer, but the device complexity and operation time increase significantly
Solution Approach 1:
The patent extracts and removes air bubbles from the system by causing them to rise to the liquid surface through natural buoyancy, eliminating the need for complex suction and pressurization mechanisms. The cleaning liquid is circulated to facilitate bubble removal at the surface.
Solution Approach 2:
The system uses the natural properties of air bubbles (buoyancy) to self-remove them from the upper protective layer during the electrochemical cleaning process, without requiring external mechanical intervention for bubble elimination.
2Object-generated harmful factors
If liquid suction and pressurization are applied during cleaning, then air bubbles are removed from the foaming chamber, but the cleaning time and liquid consumption increase
Solution Approach 1:
The patent implements continuous circulation of cleaning liquid through the foaming chamber, maintaining continuous electrochemical reaction and continuous bubble removal, which eliminates the need for repeated suction-pressurization cycles and reduces overall cleaning time.
Solution Approach 2:
The system uses hydraulic circulation of cleaning liquid to naturally transport and remove air bubbles from the foaming chamber, replacing complex pneumatic-hydraulic suction and pressurization systems with simple fluid circulation.
3Reliability
If the coating layer is eluted by electrochemical reaction to remove kogation, then cleaning effectiveness improves, but air bubbles are generated that inhibit further reaction
Solution Approach 1:
The patent introduces cleaning liquid as an intermediary medium that facilitates the electrochemical reaction for kogation removal while simultaneously serving as a vehicle to transport and remove the air bubbles generated during the reaction, preventing bubble accumulation on the coating layer.
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 method allows for efficient and simple removal of kogation without the need for liquid suction or pressurization, reducing the time and liquid required, and maintains the electrochemical reaction's effectiveness by eliminating air bubbles through foaming, thereby improving the ejection characteristics of the liquid.
Implementation Method 1
applying a voltage to the coating layer to produce an electrochemical reaction between the coating layer and the liquid
Implementation Method 2
the heat generating resistive element is made to generate heat, a liquid is heated suddenly and is made to foam
Implementation Method 3
a liquid is heated suddenly and is made to foam in a liquid contact area located above the heat generating resistive element. The foaming causes pressure with which the liquid is ejected
Data Source
AI summary
A method for cleaning a liquid ejection head, including a flow path forming member forming a liquid flow path, a heat generating resistive element, and a coating layer covering the heat generating resistive element and in contact with the liquid, in which the heat generating resistive element is made to generate heat and the liquid is made to be ejected from ejection ports, the method including: applying a voltage to the coating layer to produce an electrochemical reaction between the coating layer and the liquid, and causing the coating layer to be eluted into the liquid, thereby removing kogation deposited on the coating layer; and causing the heat generating resistive element to generate heat and causing the liquid to be ejected from the ejection ports while a voltage is applied to the coating layer continuously or intermittently, thereby eliminating air bubbles generated due to the electrochemical reaction.