壓電蜂鳴器與最佳化設計之參數鑑別與電聲分析

Abstract

本論文的研究著重於建立設計蜂鳴器的計設方法，首先利用質量增加法(added-mass method)做鑑定集中參數的法方，經由簡單的實驗完成系統的參數鑑別，接著根據有限元素的電聲參數結果建立壓電的蜂鳴器的集中參數模型。透過有限元素分析法(FEM)塑造壓電片的架構開始，接著把有限元素模型利用機電雙埠理論模擬頻率響應後，使用質量增加法(added-mass method)做鑑定集中參數的方法，在利用機電聲(EMA)類似電路模擬阻抗與聲壓曲線。在衣據此模型，做蜂鳴器的最佳化計設，使其目的在使蜂鳴器在驅動頻率上產生最大的聲壓。利用田口法(Taguchi method)、設計圖表法、約束情況下的最佳化設計以及靈敏度分析做最佳化設計，其模擬結果將會合實驗做比較，証明此方法能有效提升聲壓。最後將會對壓電蜂鳴器的設計做一設計方針。

In this paper, an optimization technique is presented for design of piezoelectric buzzers. Lumped parameter models of piezoelectric buzzers are established with finite element-based electroacoustic parameter identification procedures. The analysis starts with modeling the diaphragm structure by using finite element method (FEM). The FEM model is then converted into electro-mechanical two-ports to fit into the electro-mechano-acoustical (EMA) analogous circuit. Electrical impedance of the piezoelectric diaphragm is simulated using the model. An ‘added-mass’ method is developed to identify the lumped parameters. Electrical impedance and on-axis sound pressure level (SPL) of a piezoelectric buzzer (containing the diaphragm and case) can be simulated by solving the loop equations of the analogous circuits. On the basis of the model, optimal structural parameters and configurations for the buzzer can be found to maximize the sound pressure output, using the Taguchi method and constrained optimization. Simulation and experimental results showed that the performance has been significantly improved using the optimal design. Design guidelines for the piezoelectric buzzers are summarized.