Liquid Ejecting Apparatus Circulation Control for Nozzle Clogging
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Solution Overview
Problem
Inkjet printers face issues with uneven solid content concentration in ink, leading to nozzle clogging and printing defects when powered off and then turned back on, due to settled solid content, and existing circulation methods risk gas inflow which exacerbates the problem.
Innovation Solution
A liquid ejecting apparatus with a dual passage system and a liquid driving unit that maintains a meniscus in nozzles using distinct flow rates, and includes a cap and flexible member to prevent gas inflow during maintenance, ensuring ink circulation without air entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ink is circulated between the tank and printing head to prevent solid content settlement, then uneven concentration is improved, but gas inflow into the circulation passage occurs
Solution Approach 1:
The circulation system is divided into two separate passages: a first passage that allows bidirectional ink circulation between the tank and printing head, and a second passage that provides a dedicated gas venting path from the tank to the atmosphere. This segmentation enables independent control of ink flow and gas evacuation, preventing gas contamination in the ink circulation while maintaining concentration uniformity.
Solution Approach 2:
A valve unit is introduced as an intermediary component in the first passage to control ink flow direction and prevent gas entry. The valve unit selectively opens or closes passages based on operational mode (circulation vs. ejection), acting as a mediator that allows beneficial ink circulation while blocking harmful gas inflow into the ejection head.
2Reliability
If ink circulation is performed at high flow rate to break meniscus and prevent clogging, then nozzle reliability is improved, but gas may be drawn into the nozzles
Solution Approach 1:
The system dynamically adjusts ink flow characteristics by controlling the liquid driving unit to operate at different flow rates. During maintenance circulation, high flow rate is used to break meniscus and prevent clogging. During normal ejection, flow rate is reduced to maintain stable meniscus and prevent gas entry. This dynamic adaptation resolves the contradiction between reliability improvement and gas prevention.
Solution Approach 2:
The ink circulation is performed periodically as a maintenance operation rather than continuously. During these periodic maintenance cycles, the system temporarily accepts high flow rate operation to break meniscus and redistribute solid content, then returns to normal low flow rate operation for ejection, preventing gas entry during critical ejection phases.
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 gas inflow and maintains even ink distribution, reducing nozzle clogging and improving printing quality by ensuring stable ink circulation and distribution.
Implementation Method 1
The liquid is moved, by the driven liquid driving unit, at a first flow rate that maintains a meniscus of the liquid inside the nozzles after the liquid is moved at a second flow rate that is faster than the first flow rate.
Data Source
AI summary
A liquid ejecting apparatus comprising a liquid ejection head that ejects a liquid via nozzles; a first passage that communicates with the liquid ejection head, the first passage being configured to supply the liquid to the liquid ejection head; a second passage that communicates with the first passage in the liquid ejection head, the second passage forming, in cooperation with the first passage, a circulation passage; and a liquid driving unit provided in the circulation passage, the liquid driving unit being configured to move the liquid in the circulation passage when driven. The liquid is moved, by the driven liquid driving unit, at a first flow rate that maintains a meniscus of the liquid inside the nozzles after the liquid is moved at a second flow rate that is faster than the first flow rate.