條狀激振式揚聲器之最佳化設計及研製

Abstract

本文探討不同材料常數對聲壓曲線的影響，根據比較結果得知激振位置影響聲壓曲線最大，因此利用改變片狀音圈激振方式，將橫向激振位置改為垂直條狀激振，改善揚聲器的音谷及提高高頻的聲音表現，達到聲壓平滑化的效果。在理論分析中運用數值分析Rayleigh-Ritz法及有限元素法進行聲壓位準模擬，並結合總域極小值最佳化理論找出不同振動板長寬比所適合的垂直條狀激振數目及垂直條狀激振之最佳位置，經由最佳化結果顯示若為單一纖維方向材料振動板(如：巴莎木、碳纖)，在相同長寬比及相同激振條數下最佳激振位置會相似，並依照最佳化結果實際製作垂直條狀激振揚聲器並進行聲壓量測，根據橫向激振揚聲器與垂直條狀激振揚聲器聲壓量測實驗比較結果顯示垂直條狀激振揚聲器有較平滑之聲壓曲線。

In this thesis, the effects of different material constants on sound pressure level (SPL) are studied. According to the results of the theoretical SPL, the exciter location is the most influential parameter regarding sound pressure level. Consequently, different flat-panel exciter locations are designed to eliminate the SPL dips and enhance high frequency performance via an optimization approach. Both the finite element method and the Rayleigh-Ritz method are used to simulate the frequency responses of flat-panel speakers. The first Rayleigh integral is used to construct the SPL curve of the speaker. The optimal excitation locations of several composite diaphragms with different aspect ratios are determined using a global optimization technique. The results of the optimal designs have shown that diaphragms with similar characteristics have similar excitation locations. The feasibility of the optimal design method has been validated by the experimental results.