Ultrasonic Sensor Piezoelectric Element Layer Segmentation
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Solution Overview
Problem
Conventional ultrasonic sensors with multilayer piezoelectric elements face challenges in independently adjusting sound pressure during transmission and sensitivity during reception, as these characteristics are inversely proportional to the number of laminated layers, making it difficult to optimize both parameters simultaneously.
Innovation Solution
The ultrasonic sensor design incorporates a piezoelectric element with distinct transmission and reception regions, where the transmission region employs a four-layer structure and the reception region uses a one-layer structure, with different impedance characteristics to allow independent adjustment of sound pressure and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the number of laminated layers of the piezoelectric element is increased, then sound pressure in transmission is increased, but sensitivity in reception is decreased
Solution Approach 1:
The piezoelectric element is divided into separate transmission region and reception region with different numbers of laminated layers. The transmission region has more layers to increase sound pressure, while the reception region has fewer layers to maintain sensitivity. This spatial segmentation allows independent optimization of both functions.
Solution Approach 2:
Different regions of the piezoelectric element are assigned different local qualities (different numbers of laminated layers) according to their specific functions. The transmission region uses more layers for high sound pressure, while the reception region uses fewer layers for high sensitivity, creating local quality variations that resolve the contradiction.
2Measurement precision
If the number of laminated layers of the piezoelectric element is reduced, then sensitivity in reception is increased, but sound pressure in transmission is decreased
Solution Approach 1:
The piezoelectric element is segmented into transmission and reception regions with different layer counts. The reception region uses fewer layers to achieve high sensitivity, while the transmission region compensates with more layers to maintain sound pressure, resolving the contradiction through functional separation.
Solution Approach 2:
Local quality variations are introduced by assigning different numbers of laminated layers to different regions. The reception region has fewer layers for high sensitivity, while the transmission region has more layers for adequate sound pressure, allowing both requirements to be satisfied simultaneously.
3Device complexity
If a conventional multilayer piezoelectric element is used, then the structure is simple, but it is difficult to adjust sound pressure and sensitivity independently
Solution Approach 1:
The piezoelectric element is segmented into functionally distinct transmission and reception regions with different numbers of laminated layers. This segmentation enables independent adjustment of sound pressure and sensitivity while maintaining a relatively simple overall structure, as no additional components are required.
Solution Approach 2:
Local quality variations in the form of different laminated layer counts are introduced within the piezoelectric element itself. This allows independent optimization of sound pressure and sensitivity without adding external adjustment mechanisms, maintaining structural simplicity while achieving adaptability.
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 the ultrasonic sensor to effectively adjust and optimize both sound pressure and sensitivity independently, enhancing sensing accuracy and signal-to-noise ratio, particularly in environments where external noise is negligible and circuit noise is dominant.
Implementation Method 1
a piezoelectric element that is bonded to an inner surface of the bottom portion and that performs bending vibration together with the bottom portion
Implementation Method 2
a piezoelectric element including a piezoelectric layer having a transmission region and a reception region
Implementation Method 3
the transmission region and the reception region are formed at positions adjacent to each other
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An ultrasonic sensor includes a case (60) having a bottom portion (62), and a piezoelectric element (50) that is bonded to an in face (62S) of the bottom portion and performs bending vibration together with the bottom portion. The piezoelectric element includes a piezoelectric layer (40) having a transmission region (40N) and a reception region (40M), an electrode (30), a transmission electrode (20) opposing the electrode (30) with the transmission region interposed therebetween, and a reception electrode (10) opposing the electrode (30) with the reception region interposed therebetween. The transmission region (40N) and the reception region (40M) are formed at positions adjacent to each other.