Liquid Discharge Head Cleaning via Segmented Electrochemical Dissolution
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Solution Overview
Problem
The existing methods for cleaning liquid discharge heads, such as those described in Japanese Patent Laid-Open No. 2008-105364, suffer from uneven dissolution of the protective layer due to the upper protective layer and counter electrode being in the same liquid chamber, leading to instability in liquid discharge.
Innovation Solution
A method is introduced where the covering layer and electrode, which undergo an electrochemical reaction to dissolve kogation, are not in the same liquid chamber, with increased resistance between them to ensure uniform dissolution, using independent supply ports and varying cross-sectional areas to maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the upper protective layer and counter electrode are arranged in the same liquid chamber to enable electrochemical reaction, then kogation on the heat application portion can be removed, but uneven dissolution occurs leading to instability in liquid discharge
Solution Approach 1:
The liquid chamber is divided into a first liquid chamber containing the upper protective layer and a second liquid chamber containing the counter electrode. By segmenting the liquid chamber, the patent enables electrochemical reaction for kogation removal while preventing uneven dissolution that would occur if both components were in the same chamber, thus maintaining liquid discharge stability.
2Object-generated harmful factors
If the upper protective layer serves as anode electrode to dissolve and remove kogation, then cleaning effect is achieved, but the protective layer thickness becomes uneven
Solution Approach 1:
By placing the upper protective layer and counter electrode in separate liquid chambers, the patent segments the electrochemical reaction environment. This segmentation ensures uniform current distribution and uniform dissolution of the protective layer, preventing thickness unevenness while maintaining effective kogation removal.
Solution Approach 2:
The patent introduces a first liquid chamber as an intermediary between the upper protective layer and the counter electrode. This intermediary chamber enables the electrochemical reaction to proceed uniformly by controlling the reaction environment, thus maintaining protective layer thickness uniformity while achieving cleaning effect.
3Object-generated harmful factors
If electrochemical reaction is applied to remove kogation, then cleaning function is provided, but thermal transfer from heat application portion becomes uneven
Solution Approach 1:
The patent segments the liquid chamber into separate first and second liquid chambers for the upper protective layer and counter electrode, respectively. This segmentation prevents uneven dissolution of the protective layer, which in turn maintains uniform thermal transfer from the heat application portion by preserving the protective layer's integrity and thickness uniformity.
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 approach suppresses variations in the degree of dissolution of the covering layer, maintaining the stability of the liquid discharge process by ensuring uniform removal of kogation and preventing uneven thermal transfer.
Implementation Method 1
a heat-generating resistor... configured to heat liquid rapidly at a contact portion (heat application portion) with liquid located above the heat-generating resistor by generating heat
Implementation Method 2
applying a voltage to the covering layer and the electrode to cause an electrochemical reaction between the covering layer and the liquid and dissolve the covering layer into the liquid to remove kogation accumulated on the covering layer
Data Source
AI summary
A method of cleaning a liquid discharge head having a substrate provided with a supply port, a heat-generating resistor covered with a covering layer, a liquid chamber forming member configured to form a liquid chamber, and at least one electrode and being configured to discharge liquid supplied to the liquid chamber from the supply port by causing the heat-generating resistor to generate heat, includes applying a voltage to the covering layer and the electrode to cause an electrochemical reaction between the covering layer and the liquid and dissolve the covering layer into the liquid to remove kogations accumulated on the covering layer, in which the covering layer and the electrode to which the voltage is to be applied are not provided in the same liquid chamber having the same cross-sectional area in a direction from the covering layer toward the electrode.