Liquid Ejection Apparatus Dynamic Pressure Control for Impurity Removal
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Solution Overview
Problem
Existing liquid ejection apparatuses face challenges in efficiently removing air bubbles and foreign matters from channels due to complex constructions and arrangements, where air bubbles and foreign matters often get trapped in 'dead water' areas, making it difficult to carry them with the ink flow.
Innovation Solution
A liquid ejection apparatus that initiates with a relatively small unit-time supply amount to gather air bubbles and foreign matters, then increases the supply amount stepwise to accelerate the ink flow, effectively moving and discharging these impurities by controlling the supply device and channel resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant pressure is applied to circulate ink through channels, then the circulation operation is maintained, but air bubbles and foreign matters remain trapped in dead water areas and cannot be effectively removed
Solution Approach 1:
The patent applies dynamic pressure control by varying the pressure applied to the ink in two distinct phases: a first phase with lower pressure to gather impurities into the main flow, and a second phase with higher pressure to accelerate the flow and discharge the gathered impurities. This dynamic adjustment resolves the contradiction by adapting pressure conditions to different operational requirements rather than maintaining constant pressure.
Solution Approach 2:
The patent implements periodic action through alternating circulation and discharge operations. During circulation, impurities are gradually gathered into the main flow; during discharge, high pressure accelerates the flow to expel the gathered impurities. This periodic alternation between gathering and discharging phases enables effective removal of air bubbles and foreign matters while maintaining circulation stability.
2Productivity
If the ink flow is accelerated to move air bubbles and foreign matters, then discharge efficiency improves, but air bubbles and foreign matters in corner parts cannot be gathered into the main stream
Solution Approach 1:
The patent applies preliminary action by first performing the circulation operation to gather air bubbles and foreign matters from corner parts into the main stream before executing the discharge operation. This preliminary gathering phase ensures that impurities are concentrated and positioned appropriately before the high-speed discharge phase begins, resolving the contradiction between gathering efficiency and discharge speed.
Solution Approach 2:
The patent segments the impurity removal process into two distinct operational phases: circulation (gathering) and discharge (expulsion). During circulation, lower pressure allows gentle gathering of impurities from corner parts without disrupting the ink flow pattern. During discharge, higher pressure accelerates the flow to expel the gathered impurities efficiently. This segmentation allows each phase to optimize for its specific function.
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
This approach efficiently removes air bubbles and foreign matters from the channels, even with complex constructions, by accelerating the ink flow and applying high pressure to all ejection openings, preventing unnecessary ink discharge and ensuring stable operation.
Implementation Method 1
the pump is operated to feed the ink in the ink tank to the ink channels at a specific pressure to circulate the ink in the circulation passage
Implementation Method 2
The member accumulates an elastic force by a pressure of the ink entering into the chamber while the pump is operated with the valve being closed, and then urges the ink toward the printing head unit when the valve is opened to release the elastic force accumulated in the elastic member
Data Source
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AI summary
A liquid ejection apparatus (101) including: a liquid ejection head (1) including: an inlet opening (72a) into which liquid flows; an outlet opening (73a) from which the liquid having flowed into the inlet opening flows; an inside channel (72,73) communicating the inlet opening and the outlet opening with each other; and a plurality of ejection openings (108) through which is ejected the liquid having flowed through a plurality of individual channel (132) branched from the inside channel; a tank (80) storing the liquid to be supplied to the liquid ejection head; a supply channel (82) communicating the tank and the inlet opening with each other; a return channel (83) communicating the tank and the outlet opening with each other; a supply device (86) configured to supply the liquid in the tank to the inside channel via the supply channel; and a controller (16) configured to control the supply device, wherein the controller is configured to control the supply device to perform a circulating operation in which the liquid in the tank is transferred to the supply channel, the inside channel, and the return channel in order and returns to the tank, and wherein the controller is configured to control the supply device such that a unit-time supply amount that is an amount of the liquid to be supplied to the inside channel per unit time in a first period in the circulating operation is less than that in a second period that is after the first period.