具反向層之多層超音波壓電換能器特性

Abstract

具反向層之超音波壓電換能器近年來受到各方重視，被認為是一種設計寬頻換能器的好方法。本文將提出具反向層雙層壓電片之超音波壓電換能器的解析模型，並利用轉移矩陣法來分析有關換能器之電輸入阻抗及效率。 文中說明換能器各結構層，包含單、雙層壓電片且具反向層、背部材料及匹配層等之設計理念，並探討反向層厚度比、背部材料特徵阻抗及有無匹配層對於換能器頻寬及效率之影響，進而找出其中最佳之設計。 本研究成功地以轉移矩陣法模擬出具反向層之多層超音波壓電換能器結構之理論及數值計算，有助於完成雙頻操作模式被使用在大部分超音波應用中之諧波影像或寬頻等特性。

Recently, ultrasonic piezoelectric transducer with an inversion layer has been gaining interest in the development of broadband transducer. In this research we present an analytical model for the analysis of double-layer ultrasonic piezoelectric transducers with an inversion layer. We also analyzed electric input impedance and efficiency of transducers by transfer matrix method.

The design of transducers including single and double-layer piezoelectric films with an inversion layer, backing material, and matching layer is presented. Effects of inversion layer ratio and characteristic impedance of backing material on the performace are studied. Whether transducer bandwidth and efficiency have matching layers or not we make sure of those effects.

Finally, numerical calculations of multilayer ultrasonic piezoelectric transducers by transfer matrix method is examined to understand the characteristics of the transducers working in dual-frequency operation mode, which has been used in harmonic image or broadband characteristic of most ultrasonic applications.