Piezoelectric Device Electrode Orientation for Sensitivity
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Solution Overview
Problem
Piezoelectric devices utilizing a strain in the 33 direction face challenges in improving piezoelectric properties due to misalignment between the orientation direction and poling direction of the piezoelectric member, leading to inefficient energy conversion and limited imaging capabilities in ultrasound probes.
Innovation Solution
A piezoelectric device with a pair of electrodes placed on a piezoelectric member, where the electrodes extend in directions perpendicular to the thickness direction and the orientation direction, allowing for a coincident poling and orientation direction, enhancing piezoelectric properties and energy conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If electrodes are placed to extend in the thickness direction of the piezoelectric member, then the inter-electrode distance can be reduced, but the sensitivity during receiving of ultrasound deteriorates
Solution Approach 1:
The patent transitions from the conventional configuration where electrodes extend in the thickness direction to a new configuration where electrodes extend in the radial direction (parallel to the thickness direction but perpendicular to the orientation direction). This dimensional reorientation allows the electric field to be applied radially while maintaining a larger inter-electrode distance, thereby improving sensitivity without compromising the piezoelectric effect efficiency.
2Device complexity
If the orientation direction and poling direction are misaligned, then the device structure can be simplified, but the piezoelectric properties deteriorate
Solution Approach 1:
The patent introduces asymmetry in the electrode configuration relative to the piezoelectric member's orientation. By placing electrodes to extend in the radial direction rather than aligning with the orientation direction, the electric field application becomes asymmetric with respect to the crystal orientation. This asymmetric configuration enables the poling direction to coincide with the orientation direction, optimizing piezoelectric properties while maintaining structural simplicity through the unimorph design.
3Device complexity
If a one-dimensional array of diaphragms is used, then the device complexity is reduced, but the imaging capability deteriorates
Solution Approach 1:
The patent enhances the functionality of each individual piezoelectric member by optimizing its electrode configuration and piezoelectric properties. This improvement in single-element performance contributes to overall system capability, making the transducer more versatile for different imaging modes including three-dimensional imaging, thereby reducing the need for complex array configurations.
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 results in improved piezoelectric properties and efficient energy conversion, enabling high-resolution three-dimensional imaging with ultrasound probes and effective droplet discharge in the piezoelectric device.
Implementation Method 1
During transmitting, it is operable to convert electric energy to mechanical energy (vibration of diaphragms), and further convert the mechanical energy to acoustic energy (ultrasound)
Implementation Method 2
During receiving, it is operable to convert acoustic energy (ultrasound) to mechanical energy (vibration of diaphragms), and further convert the mechanical energy to electric energy
Implementation Method 3
A piezoelectric member becomes most efficient (in an index representing performance of a piezoelectric member, k-value: electromechanical coupling coefficient becomes higher), when utilizing a strain in the same direction (33 direction) as a direction of electric field
Data Source
AI summary
In a piezoelectric device, an ultrasound probe, and a droplet discharge unit of the present invention, each of a pair of first and second electrodes is placed on a piezoelectric member having a single orientation in a direction perpendicular to a thickness direction thereof to extend in a direction perpendicular to the thickness direction or along the thickness direction and in a direction perpendicular to the direction of the orientation. Therefore, the piezoelectric device of the present invention has excellent piezoelectric properties. Further, the ultrasound probe and the droplet discharge unit of the present invention have good efficiency.