Liquid Ejection Apparatus Negative Pressure Control
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Solution Overview
Problem
Existing liquid ejection apparatuses face challenges in quickly stopping liquid flow to prevent leakage from ejection ports, which prolongs the time it takes to stop circulation and can lead to contamination or mixing of colors during wiping operations.
Innovation Solution
A method that involves stopping the supply of liquid by closing the opening/closing valve and then stopping the negative pressure generating pump, maintaining negative pressure downstream to prevent leakage, allowing for rapid cessation of liquid flow while keeping ejection ports under negative pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circulation of liquid is continued until water head difference becomes zero even after opening pressurizing and negative pressure spaces to atmosphere, then liquid leakage from ejection ports is reduced, but the time until circulation stops increases
Solution Approach 1:
The pressurizing space is opened to atmosphere before the negative pressure space, creating a preliminary pressure equalization that prepares the system for faster shutdown. This sequential opening allows the water head difference to be reduced more quickly while still preventing liquid leakage, as the pressurizing space expansion occurs in advance to facilitate rapid circulation stoppage.
2Productivity
If wiping operation is performed while liquid is circulated, then cleaning efficiency is improved, but cleaning liquid enters ejection ports and mixes with circulated liquid causing contamination
Solution Approach 1:
The pressurizing space is opened to atmosphere before the wiping operation begins, creating a preliminary pressure equalization that prevents liquid leakage during cleaning. This advance preparation allows the wiping operation to be performed safely during circulation without risking contamination, as the pressure conditions are already favorable for preventing liquid escape from ejection ports.
3Speed
If opening/closing valve is closed to stop liquid supply, then liquid flow stops, but pressure fluctuation causes liquid leakage from ejection ports
Solution Approach 1:
The pressurizing space acts as an intermediary between the opening/closing valve and the ejection ports. When the valve closes to stop liquid supply, the pressurizing space absorbs the pressure fluctuation through its expansion, preventing direct pressure transmission to the ejection ports that would cause liquid leakage. This intermediary mechanism decouples the rapid flow stoppage from the pressure instability.
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 enables the liquid ejection apparatus to stop the liquid flow in a short period, reducing leakage and preventing contamination or color mixing, thus enhancing operational efficiency and reliability.
Implementation Method 1
a negative pressure space section that applies a negative pressure to the downstream side of the circulation flow path for circulating the liquid
Implementation Method 2
a pressurizing space section that applies a positive pressure to the upstream side of a circulation flow path for circulating a liquid
Implementation Method 3
an opening/closing valve that opens and closes to control supply of the liquid to the pressurizing space section
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A liquid ejection apparatus includes a supply control section 401 that controls the supply and stop of a liquid to pressure chambers communicating with ejection ports to eject the liquid, and a negative pressure generating section 1004 that generates a negative pressure. The liquid ejection apparatus also includes a negative pressure control unit 230 using the negative pressure generated by the negative pressure generating section 1004 to adjust the pressure of the liquid flowing through a collection channel. To stop a flow of the liquid, the supply control section 401 stops the supply of the liquid, and then the negative pressure generating section 1004 is stopped.