Circulation Unit Air Bubble Prevention Piezoelectric Pump
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Solution Overview
Problem
Existing liquid ejection apparatuses face issues with air bubbles entering the circulating pump, leading to decreased pressure generation and ejection stability due to malfunctioning float-type liquid level sensors, which can result in low ink levels and exposure of pump components to air.
Innovation Solution
A circulation unit with pressure adjustment units and a piezoelectric diaphragm pump is designed to manage pressure and prevent air entry, featuring a configuration where the pump inlet is positioned low in the second pressure control chamber and the outlet is high in the first pressure control chamber, with a bypass passage to maintain constant pressure and prevent negative pressure buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If float-type liquid level sensors are used to monitor ink levels, then ink level detection is achieved, but the sensors malfunction due to ink bubbling causing air entry into the pump
Solution Approach 1:
The patent removes the float-type liquid level sensors from the system entirely and replaces them with a pressure sensor that detects air entry directly at the pump inlet. This extraction eliminates the malfunctioning sensors while preserving the critical function of detecting when air enters the circulation system.
Solution Approach 2:
The patent introduces a pressure sensor as an intermediary device that indirectly monitors air entry by measuring pressure changes in the circulation system. Instead of directly detecting ink levels with unreliable float sensors, the pressure sensor acts as a mediator that detects the presence of air bubbles through pressure variations, providing reliable detection without the bubbling interference problem.
2Productivity
If the circulating pump operates with low ink levels, then circulation continues, but air enters the pump causing pressure generation failure
Solution Approach 1:
The pressure sensor is positioned at the pump inlet to detect air entry before it significantly impacts pump performance. By taking preliminary action to detect air presence early, the system can alert operators or take corrective measures before the air bubbles accumulate and cause pressure generation failure, thus maintaining both circulation continuity and reliable pressure generation.
Solution Approach 2:
The pressure sensor provides continuous feedback about the ink level and air entry conditions to the control system. This feedback mechanism allows the system to monitor the circulation status in real-time and take appropriate actions (such as stopping the pump or alerting operators) when air entry is detected, preventing the progression to pressure generation failure while maintaining productivity during normal operation.
3Volume of moving object
If piezoelectric pump is used for circulation, then compact design is achieved, but the pump cannot generate desired pressure when air enters
Solution Approach 1:
The pressure sensor at the pump inlet provides early detection of air entry, allowing preliminary action to be taken before the air significantly impacts the piezoelectric pump's pressure generation capability. This early warning system enables operators to address air entry issues before they compromise the pump's performance, maintaining both the compact design and reliable pressure generation.
Solution Approach 2:
The pressure sensor provides continuous feedback to the control system about air entry conditions, enabling real-time monitoring and control adjustments. This feedback mechanism protects the compact piezoelectric pump from operating with air bubbles that would reduce pressure generation, ensuring the small pump maintains its full pressure generation capability when needed.
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 configuration enhances the stability of the ejection process by preventing air from entering the pump, maintaining consistent pressure, and ensuring efficient ink circulation, thereby improving the reliability and performance of the liquid ejection apparatus.
Implementation Method 1
a small piezoelectric pump serving as the circulating pump
Implementation Method 2
a first flexible member that forms a surface of a portion of the first pressure control chamber and that is configured to be displaceable
Data Source
AI summary
A relation of VV<V2 is satisfied, where VV is a volume of fluid passing a communication port of a first pressure control chamber of a first pressure adjustment unit and a fourth passage communicating with a circulating pump and the first pressure control chamber, in a direction from the first pressure control chamber toward the fourth passage in a period from a time when operation of the circulating pump is stopped to a time when pressure in the first pressure control chamber and pressure in the second pressure control chamber become equal to each other, and V2 is a volume of the fourth passage.