本論文研究自製之非均勻厚度PZT壓電陶瓷體，與其所製成的聚焦式超聲波換能器；研究範圍包括理論模擬、製程實作、與實驗量測。
　　在理論方面採用有限元素法及等效電路模型二種方法。首先利用ANSYS有限元素法軟體進行阻抗分析，再與PSpice軟體之等效電路模擬結果作比對。Spice等效電路模型方面，採用A. Püttmer等效電路模型，將壓電材料分成聲學介質與電路端兩個部分，分別可用傳輸線與電容代替，再加上控制源估計機電轉換效應；同時參考G. Lypacewicz之Mason等效電路模型，完成非均勻厚度壓電陶瓷體等效電路模型。在製程實作與實驗量測方面，首先於實驗室中製作均勻厚度與非均勻厚度的壓電陶瓷體，以阻抗分析儀量測其頻率響應，並與模擬的結果作比對；接著以自製之壓電陶瓷體，設計製作出點聚焦的超聲波換能器，並結合聲場掃瞄系統與水聽器，以了解自製換能器的性能。實驗結果發現具有銅背層的非均勻壓電體換能器，確實能增加換能器頻寬。
　　經由本文之實驗與模擬分析，證明非均勻厚度壓電陶瓷體等效電路的可行性，可以作為設計壓電超音波換能器的的依據，未來可以設計出頻寬更寬、中心頻率更高的超音波換能器，作為非破壞性檢測的應用。

　　This research investigates the focusing acoustic wave transducers, which are made from PZT piezoelectric ceramic with non-uniform thickness, and their performance. The investigation covers theoretical simulation, fabrication, and experimental measurement.
　　The simulation is based on finite element method (FEM) and equivalent circuit model. The piezoelectric impedance analysis has been carried out with ANSYS FEM analysis and PSpice equivalent circuit simulation. The equivalent circuit model of piezoelectric material is based on A. Püttmer’s work (1997), which consists of two parts, namely acoustic part and electric part. Both parts can be substituted by transmission lines and capacitors. Using an improve model proposed by G. Lypacewics (2002), the characteristics of a piezoelectric ceramic with non-uniform thickness is studied. The uniform and non-uniform piezoelectric ceramic disks are fabricated and measured by an impedance analyzer. The acoustic wave transducers are fabricated by those ceramics. The transducers’ properties are investigated with an acoustic field scanning system. It shows that the bandwidth of the transducer is improved with non-uniform thickness and proper backing material.
　　The experimental and simulation results of this work pave a way for designing a focusing ultrasound transducer with non-uniform thickness PZT ceramics. With wider bandwidth and higher central frequency, such transducer can be very useful for future non-destructive evaluation (NDE).

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