Piezoelectric Fluid Pump Air Bubble Detection
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Solution Overview
Problem
Existing fluid feeding and ejection devices face an increase in size due to the need for separate air bubble detection systems, which complicates the detection and removal of air bubbles in pump chambers, hindering efficient fluid circulation and ejection.
Innovation Solution
Incorporating a piezoelectric element that accumulates electric charges and deforms to change the pump chamber volume, driven by a waveform voltage signal, and an air bubble determining unit that detects current changes to determine the presence of air bubbles without requiring a separate detection device, allowing for accurate detection within a predetermined period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate air bubble detection device is provided in the circulation pump, then air bubbles can be detected and removed from the pump chamber, but the device size increases
Solution Approach 1:
The patent combines the air bubble detection function with the existing piezoelectric element and drive circuitry. The air bubble determining unit utilizes the same piezoelectric element that drives the pump chamber, detecting current changes during the drive cycle to identify air bubbles. This merging of detection functionality into the existing drive system eliminates the need for separate detection hardware, thereby maintaining compact device size while preserving air bubble detection capability.
Solution Approach 2:
The piezoelectric element serves dual functions: it acts as both the drive actuator for pump chamber volume change and as the sensing element for air bubble detection. The drive circuitry also serves dual purposes by providing both the drive signal and the detection pathway for monitoring current changes. This multi-functionality allows the system to maintain reliability through air bubble detection without adding separate dedicated components.
2Reliability
If a separate air bubble detection device is provided in the fluid ejection device, then air bubbles can be detected in the pump chamber, but the device size increases
Solution Approach 1:
The patent applies the same merging principle to fluid ejection devices. The air bubble determining unit is integrated into the existing drive circuitry for the piezoelectric element, using the current changes during the drive cycle to detect air bubbles. This integration eliminates the need for separate detection devices, maintaining compact device size while ensuring reliable air bubble detection before fluid ejection.
Solution Approach 2:
The piezoelectric element and drive circuitry serve multiple functions including both the ejection drive and air bubble detection. The current monitoring during the drive cycle allows the same hardware to perform both actuation and sensing functions, preventing device size increase while maintaining detection reliability for fluid ejection applications.
3Measurement precision
If air bubbles are present in the pump chamber, then the piezoelectric element deforms differently, but detecting this requires additional detection devices
Solution Approach 1:
The system uses its own drive current as the sensing signal for air bubble detection. The air bubble determining unit monitors the current changes that occur during the piezoelectric element's operation, utilizing the element's own electrical characteristics to detect air bubbles. This self-service approach eliminates the need for external detection devices, reducing system complexity while maintaining detection accuracy.
Solution Approach 2:
The drive current serves as an intermediary that carries information about air bubble presence. By monitoring the current changes during the drive cycle, the system uses the electrical signal as a mediator to detect air bubbles without requiring separate physical sensing elements. This intermediary approach simplifies the detection system while maintaining measurement precision.
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 enables small-sized fluid feeding pumps by integrating air bubble detection directly into the system, ensuring efficient fluid circulation and ejection without the need for additional detection devices, maintaining device compactness.
Implementation Method 1
a piezoelectric element which accumulates electric charges inside when a voltage is applied, and which deforms according to an amount of accumulated electric charges and thus increases or decreases the volume of the pump chamber
Implementation Method 2
an air bubble determining unit which detects a current flowing through the piezoelectric element within a predetermined period after the drive signal is applied to the piezoelectric element, and thus determines whether there are air bubbles in the pump chamber or not
Data Source
AI summary
A fluid feeding pump which varies a volume of a pump chamber and thus feeds a fluid out of the pump chamber, includes: a piezoelectric element which accumulates electric charges inside when a voltage is applied, and which deforms according to an amount of accumulated electric charges and thus increases or decreases the volume of the pump chamber; a drive unit which applies a drive signal with a waveform increasing to a predetermined maximum voltage and then decreasing, and thus drives the piezoelectric element; and an air bubble determining unit which detects a current flowing through the piezoelectric element within a predetermined period after the drive signal is applied to the piezoelectric element, and thus determines whether there are air bubbles in the pump chamber or not.