超音波壓電換能器多層匹配結構之研析

Analysis of Multi-Matching Layers of Ultrasonic Piezoelectric Transducer

朱雅雯(Ya-Wen Chu)

指導教授 ： 宋家驥

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.02288

摘要

在日新月異的生活中，超音波的應用已不可或缺，本文重點在探討超音波壓電換能器(Ultrasonic Piezoelectric Transducer)配置多層匹配層（Matching Layer），其壓電片聲阻抗（Acoustic Impedance）與聲傳介質聲阻抗匹配之設計概念。
本文首先介紹壓電理論，並說明超音波壓電換能器之各層結構材料，並藉由傳輸線（Transmission Line）原理，將匹配層等效為傳輸線，在最平坦化頻率響應（Maximally Flat-Top Response）條件下推導出於n層匹配層中，每一層匹配層的阻抗值，並得到匹配層越多層則使頻寬越寬之特性。再經由壓電片波傳方程式，推導出壓電換能器之阻抗矩陣（Impedance Matrix），並針對其阻抗矩陣之架構，利用聲波能量傳遞的觀念來分析換能器內部結構，進而提出一套傳輸矩陣法（Transmission Matrix Method），用以模擬壓電換能器多層匹配層結構的數值模型。
以傳輸矩陣之方式來模擬換能器，可得到換能器機械端輸出阻抗頻率響應圖其與聲傳介質阻抗匹配，也模擬出換能器的電端輸入阻抗與頻率的關係圖，故可用於設計換能器之參考標準。本論文成功地藉由傳輸矩陣法模擬出壓電換能器多層匹配層結構的理論架構及數值計算。

關鍵字

超音波壓電換能器 ； 匹配層 ； 聲阻抗 ； 傳輸線 ； 最平坦化頻率響應 ； 阻抗矩陣 ； 傳輸矩陣法

並列摘要

In recent years, the study of ultrasonic waves has found indispensable applications in the real world. In this thesis, we present the acoustic impedance matching result of the piezoelectric thin plate and the propagation medium when we increase the number of matching layers.
To begin, we introduce the theory of piezoelectricity and explain the structure of the ultrasonic piezoelectric transducer. By extending the theory of transmission line, we find the impedances of the matching layer and find the impedances of each layer in conjunction with the maximally flat-top response. Finally, we conclude that the addition of the matching layers results in the widening of the transmission frequency for the piezoelectric transducer.
An impedance matrix for the piezoelectric transducer can be derived from the piezoelectric wave equation which is called as the transmission matrix method. Using the transmission matrix method we obtain the mechanical and electric impedances of frequency response for the ultrasonic piezoelectric transducer. At the end of this paper, we show the simulation results of the multilayer matching structure of the piezoelectric transducer which can be helpful for designing the ultrasonic piezoelectric transducer.

並列關鍵字

Ultrasonic Piezoelectric Transducer ； Matching Layer ； Acoustic Impedance ； Transmission Line ； Maximally Flat-Top Response ； Impedance Matrix ； Transmission Matrix Method

參考文獻

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