Liquid Ejection Head Voltage Control After Kogation Removal
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Solution Overview
Problem
Ink ejection in printing apparatuses using heat-generating resistors can lead to kogation formation, causing changes in ejection characteristics and stability issues due to insoluble or poorly soluble colorants, and existing methods fail to maintain consistent ejection performance regardless of the liquid ejection head's state.
Innovation Solution
A liquid ejection apparatus with a heat generating resistor, a first electrode, and a second electrode capable of conducting electricity, along with a control unit that applies a potential difference to remove kogation by dissolving the electrode surface, ensuring stable ejection characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat-generating resistors are used to eject liquid, then liquid ejection can be achieved, but kogation forms on the heater surface causing change in ejection speed
Solution Approach 1:
The patent applies preliminary action by performing a kogation removal process before the liquid ejection operation. The control unit executes electrochemical reactions to dissolve and remove kogation from the heater surface prior to ejection, ensuring the surface is clean and ready for stable ejection. This preliminary cleaning action prevents kogation-induced changes in ejection characteristics during normal operation.
Solution Approach 2:
The patent implements feedback through the control unit that detects the state of the liquid ejection head and adjusts operations accordingly. The control unit determines whether kogation removal is needed based on usage conditions and head state, then executes the removal process followed by a water supply process to rinse the heater surface. This feedback mechanism ensures ejection characteristics remain stable by adapting to the actual state of the liquid ejection head.
2Reliability
If kogation removal process is performed, then kogation is removed from heater surface, but the surface state changes compared to the initial state
Solution Approach 1:
The patent applies parameter changes by modifying the chemical and physical state of the heater surface through electrochemical reactions during the kogation removal process. The control unit adjusts electrical parameters (voltage, current, duration) to control the electrochemical dissolution of kogation. After removal, the surface state is altered, so the control unit compensates by adjusting ejection parameters or implementing additional water supply processes to restore surface consistency.
Solution Approach 2:
The patent ensures continuity of useful action by implementing a water supply process immediately after the kogation removal process. The water supply process continuously rinses the heater surface to remove residual chemicals and stabilize the surface state. This continuous action bridges the gap between the altered surface state after kogation removal and the desired stable initial state, maintaining ejection characteristic stability.
3Reliability
If water is supplied to remove kogation, then heater surface is cleaned, but ejection operation must be interrupted
Solution Approach 1:
The patent applies periodic action by implementing the kogation removal process and water supply process at scheduled intervals rather than continuously. The control unit determines appropriate timing based on usage conditions, executing the removal process periodically to prevent kogation accumulation while minimizing interruption to ejection operations. This periodic approach balances surface cleanliness with operational continuity.
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
The solution maintains stable ejection characteristics by effectively removing kogation, thereby ensuring consistent ink ejection performance and durability of the liquid ejection head.
Implementation Method 1
an ejection unit having a heat generating resistor configured to generate energy for ejecting liquid by generating heat upon energization
Implementation Method 2
first and second electrodes disposed so as to generate an electric field in a liquid chamber in a liquid ejection head. The electric field generated in a liquid chamber moves charged particles, which can be a cause of kogation, away from the heater surface
Implementation Method 3
a process is known which removes kogation by causing electrochemical reaction with ink to dissolve the heater surface
Data Source
AI summary
Provided is a technique for achieving stable ejection characteristics. To this end, during liquid ejection, a potential difference ΔVa is generated between an electrode and an opposing electrode, the potential difference ΔVa being different between a liquid ejection head in a brand-new state and a liquid ejection head which has performed a kogation removal operation before.