Inkjet Head Kogation Removal Timing Using Ejection Feedback
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Solution Overview
Problem
Existing liquid ejection apparatuses using electrothermal transducers for ink ejection suffer from kogation buildup, leading to inconsistent ejection velocities and print quality issues, particularly in pigment inks, where fixed timing kogation removal can shorten heater lifespan.
Innovation Solution
A liquid ejection apparatus with a protective portion and electrode portion for controlled kogation removal, using a control unit to determine the optimal timing based on ejection characteristics to prevent heater degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If kogation removal is executed at fixed timing, then print quality is maintained, but heater lifespan is shortened
Solution Approach 1:
The patent changes the parameter of kogation removal timing from fixed to variable based on actual kogation state. The control unit determines timing by detecting ejection velocity changes that indicate kogation accumulation, thereby executing removal only when necessary. This resolves the contradiction by maintaining print quality (through timely removal) while extending heater lifespan (by avoiding unnecessary removal operations).
Solution Approach 2:
The patent implements feedback control where the control unit monitors ejection velocity as an indicator of kogation state and adjusts kogation removal timing accordingly. When ejection velocity deviates from normal range, indicating kogation accumulation, the system triggers removal operation. This feedback mechanism ensures removal occurs at appropriate moments to maintain print quality while minimizing unnecessary operations that would shorten heater lifespan.
2Stability of the object's composition
If kogation removal is executed frequently, then ejection velocity stability is improved, but protective layer durability is reduced
Solution Approach 1:
The patent changes the frequency parameter of kogation removal from fixed/high to variable/conditional based on detected ejection characteristics. The control unit compares actual ejection velocity with reference values and only triggers removal when deviation exceeds threshold, indicating genuine kogation problems. This resolves the contradiction by maintaining ejection stability (through targeted removal) while preserving protective layer durability (by reducing unnecessary removal frequency).
3Object-generated harmful factors
If protective layer is dissolved for kogation removal, then kogation is eliminated, but heater lifespan is shortened
Solution Approach 1:
The patent uses feedback control where the control unit monitors ejection velocity as an indicator of kogation state. Dissolution of protective layer is triggered only when ejection velocity deviation indicates significant kogation accumulation. This feedback-based approach eliminates the harmful kogation effect while minimizing unnecessary protective layer dissolution, thereby extending heater lifespan.
Solution Approach 2:
The system allows the ejection system to indicate its own maintenance needs through ejection velocity changes. The control unit detects when kogation affects performance and automatically triggers protective layer dissolution only at that moment. This self-service approach ensures kogation is removed when it actually harms performance while avoiding unnecessary dissolution that would shorten heater lifespan.
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
Stabilizes ink ejection and maintains print quality while extending the lifespan of electrothermal transducer elements by effectively removing kogation at appropriate times.
Implementation Method 1
a heating resistor configured to generate heat with power supply, thereby generating energy for ejecting a liquid
Implementation Method 2
a control unit configured to control a kogation removal operation of removing kogation by applying a voltage between the protective portion and the electrode portion, and thereby dissolving the protective portion into the liquid
Data Source
AI summary
Provided is a liquid ejection apparatus capable of executing a kogation removal process at appropriate timing, thereby stably ejecting a liquid without shortening the lifespan of a head. For this purpose, the timing to execute the kogation removal operation of dissolving a metal in a protective layer through an electrochemical reaction with the liquid is determined based on information on an ejection characteristic of the liquid.