超音波換能器等效電路模擬與背膠層設計

Abstract

超音波量測系統在水利及海洋工程、非破壞檢測、醫療等領域應用已行之有年。其中超音波換能器又是系統中的重要元件之一。換能器，顧名思義即是將不同形式的能量彼此轉換，例如壓磁換能器、壓電換能器等。超音波換能器屬於壓電換能器，在進行分析時常需要機械與電子電路相關知識才能完整描述，因此國內外有許多領域的學者根據各式各樣的模擬方法，結合不同的模擬軟體或演算法，建立能夠表示真實系統的模型，如此一來能省去試誤法(trial and error)所需支出的成本。除了模擬方法以外，聲學材料的實際製造、選擇也深深影響著成品設計的優劣。 本研究主要工作除了背膠材料製備外，另以單層背膠層、匹配層和PZT陶瓷複合壓電片構成的超音波換能器系統，利用KLM等效電路模型、傳輸線理論及損失因子，透過結合實際材料參數計算等效電路的各元件數值並進行模擬。藉由模擬結果，我們可以得到換能器輸入阻抗及時域響應等預期表現，將之歸納整理後，和實驗做定性與定量的比較驗證模擬方法的可行性，以作為換能器的製作參考。最後，再進一步比較自製換能器與商用換能器以討論設計上的改進方向，比較項目包含頻寬、靈敏度、解析度等。研究中也針對背膠層材料設計做了探討，希望能夠提供未來換能器相關設計一些參考。

Ultrasonic transducers has been used for ocean engineering, noninvasive medical application, and nondestructive testing for years. The selection of modeling method and manufacture of acoustic materials are always the key of design. This thesis presents the theoretical and experimental procedures about designing the transducers. The KLM model, acoustic transmission line, and loss mechanisms were employed to calculate the input impedance and time response of the transducers. Then several home made transducers were conducted. It is demonstrated that the simulation results offers good predictions of performance of transducers. It could be useful in decreasing time of Trial and error on experiments. In the last section, we compared the commercial transducer with home made ones, inclusive of bandwidth, sensitivity, and longitudinal resolution. Besides, the literature survey and induction of backing layer are also important section of the thesis. Hope to provide some reference for future work.