Liquid Discharge Unit Circulation for White Ink Sedimentation
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Solution Overview
Problem
Inkjet devices face issues with nozzle clogging due to sedimentation and agglomeration of ink particles, leading to discharge failures and uneven image density, particularly when using high-specific-gravity white inks that settle and agglomerate, causing blockages in supply channels and nozzles.
Innovation Solution
A liquid discharge unit with a main tank, sub-tank, and interconnected supply and return channels, including pumps and valves, that actively circulates and agitates the ink to prevent sedimentation, along with a degassing module and filter to remove air bubbles and impurities, ensuring consistent ink flow and reducing the likelihood of clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-specific-gravity white ink is used to enhance whiteness and concealing properties, then image quality is improved, but ink sedimentation and nozzle clogging occur
Solution Approach 1:
The system dynamically switches between normal discharge mode and circulation mode. During circulation mode, the circulation pump activates to continuously circulate ink through the circulation channel, preventing sedimentation of high-specific-gravity white ink particles while maintaining nozzle clogging prevention
Solution Approach 2:
The system changes the operational state of the ink supply system by switching the selector valve between connecting the discharge channel and connecting the circulation channel. This parameter change (mode switching) allows the system to adapt between normal operation and sedimentation prevention states
2Device complexity
If ink is left stationary in the supply channel for a certain period, then the system is simple, but coloring material agglomerates and settles causing nozzle clogging
Solution Approach 1:
The circulation pump continuously or periodically circulates ink through the circulation channel, maintaining continuous motion of the ink to prevent sedimentation. This continuous useful action (ink circulation) counteracts the harmful effect of stationary ink causing agglomeration and clogging
Solution Approach 2:
The circulation channel acts as an intermediary pathway that allows ink to be redirected from the discharge channel back to the main tank and then redistributed. This intermediary circulation path prevents direct settling in the discharge channel while maintaining system simplicity
3Reliability
If a circulation system with pumps and valves is added to prevent sedimentation, then nozzle clogging is reduced, but device complexity increases
Solution Approach 1:
The circulation pump and selector valve serve multiple functions: they enable both normal ink discharge operation and sedimentation prevention circulation operation. This multi-functionality reduces the need for separate dedicated circulation components, thereby limiting the increase in device complexity
Solution Approach 2:
The system recycles ink that would otherwise remain stationary in the supply channel by redirecting it through the circulation channel back to the main tank. This recovery and reuse of stationary ink prevents sedimentation without requiring additional ink supplies or complex waste management systems
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 effectively prevents nozzle clogging, maintains ink flow consistency, and reduces the occurrence of discharge failures, ensuring stable and uniform image density by actively agitating and circulating the ink, thus improving the reliability and productivity of inkjet printing.
Implementation Method 1
a first pump disposed in the first liquid supply channel to feed the liquid from the main tank to the sub tank
Implementation Method 2
a second pump disposed in the liquid return channel to feed the liquid from the sub tank to the main tank
Implementation Method 3
discharging an ink (droplets) in several picoliters through ink discharge ports (nozzles)
Data Source
AI summary
A liquid discharge unit includes a main tank to accommodate a liquid, a liquid discharge head to discharge the liquid, a sub tank to supply the liquid to the liquid discharge head, a first liquid supply channel connecting the main tank and the sub tank, a second liquid supply channel connecting the sub tank and the liquid discharge head, a selector valve disposed in the second liquid supply channel, a liquid return channel connecting the selector valve and the main tank, a first pump disposed in the first liquid supply channel to feed the liquid from the main tank to the sub tank, and a second pump disposed in the liquid return channel to feed the liquid from the sub tank to the main tank.