Piezoelectric Pump Laminate Structure for Low Voltage Operation
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Solution Overview
Problem
Piezoelectric pumps with existing bimorph cells require high driving voltages and are prone to short-circuits due to potential differences between central and peripheral electrode portions, making them unsuitable for portable devices and complicating the driving circuit.
Innovation Solution
A piezoelectric pump with a laminate structure of multiple piezoelectric layers, where the central and peripheral areas are polarized opposite to each other, allowing for opposite directional bending with the same potential driving electric fields, reducing the risk of short-circuits and enabling operation with lower voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bimorph cell structure with central and peripheral electrodes is used to achieve large displacement at the central portion, then the discharge flow rate is improved, but the driving voltage becomes high and the risk of short-circuits increases
Solution Approach 1:
The piezoelectric element is divided into multiple independent piezoelectric layers (first piezoelectric layer and second piezoelectric layer) with different polarization directions. Each layer can be controlled independently, allowing the central and peripheral portions to bend in opposite directions without requiring high driving voltages. This segmentation enables achieving large displacement while maintaining lower power consumption.
Solution Approach 2:
The first piezoelectric layer and second piezoelectric layer have different local polarization qualities - the first layer is polarized in the thickness direction while the second layer is polarized in the in-plane direction. This local quality difference allows each region to respond differently to the same driving voltage, creating the opposite bending effect needed for large central displacement without increasing overall power requirements.
2Productivity
If a bimorph cell structure with separated central and peripheral electrodes is used to achieve large displacement, then the discharge flow rate is improved, but the device complexity and short-circuit risk increase
Solution Approach 1:
The electrode structures of the first and second piezoelectric layers are merged and electrically connected in parallel. The central electrode of the first layer connects to the central electrode of the second layer, and the peripheral electrode of the first layer connects to the peripheral electrode of the second layer. This merging simplifies the overall electrode structure and reduces short-circuit risk while maintaining the ability to generate opposite bending effects through the different polarization directions of the layers.
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
The solution achieves a large displacement at the central portion of the piezoelectric element with reduced thickness and lower driving voltage, enhancing the discharge volume and preventing short-circuits, thus creating a compact, power-efficient pump.
Implementation Method 1
a first piezoelectric layer 21a and a second piezoelectric layer 21b laminated to each other; the central area and the peripheral area of each of the piezoelectric layers 21a and 21b are polarized opposite to each other in the thickness directions
Data Source
Figure 1~3
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Figure 6(a)~7
AI summary
[Object] To provide a piezoelectric pump capable of generating a large displacement at a central portion of a piezoelectric element even when a driving voltage is relatively low and preventing short-circuits caused by migration. [Solving Means] A piezoelectric pump includes a pump body 1 with a pump chamber 2, and a piezoelectric element 21 that closes the pump chamber. The central area and the peripheral area of the piezoelectric element are deformed in opposite directions by applying voltages to the piezoelectric element so that the volume of the pump chamber 2 is changed. The piezoelectric element 21 is a laminate including a plurality of piezoelectric layers with electrodes interposed therebetween. The central area and the peripheral area of each piezoelectric layer are polarized opposite to each other in the thickness direction, and the electrodes are formed such that voltages in the same direction in the thickness direction are applied to the central area and the peripheral area of each piezoelectric layer. Since voltages at the same potential are applied to the electrodes formed in the same planes of the piezoelectric layers, short-circuits caused by migration can be prevented.