Liquid Feeding Control for Bubble Prevention in Ejection Heads
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Solution Overview
Problem
Liquid ejecting apparatuses face ejection failures due to air bubbles entering the supply flow path when the liquid in the supply source is nearly depleted, causing high negative pressure and potential nozzle clogging.
Innovation Solution
A liquid ejecting apparatus with a control unit that adjusts the driving of the liquid feeding portion based on the remaining liquid amount in the containing portion, reducing suction pressure and preventing air bubble formation by altering the suction and discharge operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the supply pump is driven when the liquid in the liquid supply source has nearly run out, then the liquid can be continuously supplied to the liquid ejection head, but a high negative pressure acts inside the liquid containing portion causing air bubbles to flow in and reach the nozzle
Solution Approach 1:
The patent applies dynamics by making the liquid feeding portion's suction capability variable rather than fixed. The control unit adjusts the suction pressure based on the remaining liquid amount in the supply source. When liquid level is high, stronger suction maintains continuous supply; when liquid level is low, reduced suction prevents excessive negative pressure that would draw in air bubbles. This dynamic adjustment resolves the contradiction between maintaining productivity and ensuring reliability.
Solution Approach 2:
The patent changes the operational parameters of the liquid feeding portion based on the remaining liquid amount. The control unit modifies suction pressure, suction flow rate, or suction timing as parameters depending on the liquid level in the supply source. This parameter adaptation allows the system to maintain reliable operation across different liquid levels, preventing air bubble ingress while ensuring continuous liquid supply to the ejection head.
2Speed
If the liquid feeding portion strongly sucks the liquid to maintain supply pressure, then liquid can be fed efficiently to the liquid ejection head, but air bubbles are more likely to be drawn in when liquid level is low
Solution Approach 1:
The patent makes the suction speed of the liquid feeding portion dynamic rather than constant. The control unit adjusts the suction flow rate based on the remaining liquid amount in the supply source. When liquid level is high, higher suction speed maintains efficient liquid feeding; when liquid level is low, reduced suction speed prevents air bubble formation. This dynamic control resolves the contradiction between feeding speed and harmful factor prevention.
Solution Approach 2:
The patent changes the suction flow rate parameter of the liquid feeding portion according to the liquid level in the supply source. The control unit modifies this parameter to optimize liquid feeding while preventing air bubble ingress. By adapting the suction flow rate to the remaining liquid amount, the system maintains high feeding efficiency when possible while eliminating air bubble formation when liquid is low.
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
Prevents ejection failures by managing air bubble formation and maintaining efficient liquid supply, ensuring consistent operation even when the liquid level is low.
Implementation Method 1
a liquid feeding portion provided on the supply flow path and configured to suck the liquid from the liquid containing portion and feed the liquid to the liquid ejection head
Data Source
AI summary
A liquid ejecting apparatus includes a liquid ejection head that ejects a liquid, a supply flow path that supplies the liquid from a liquid containing portion, which is replaceable and contains the liquid, to the liquid ejection head, a liquid feeding portion that is provided in the supply flow path and is configured to suck the liquid from the liquid containing portion and to feed the liquid to the liquid ejection head, and a control unit that controls driving of the liquid feeding portion. The control unit changes driving control of the liquid feeding portion in accordance with a remaining amount of the liquid in the liquid containing portion.