臺灣博碩士論文加值系統

本文旨在探討長型平面揚聲器之激振位置對揚聲行為之影響。因應現今電子產品的平面化趨勢，揚聲器有狹長化的設計需求，而傳統圓形激振器受到狹長揚聲板的寬度限制，會有聲壓感度偏低且中音谷落差大等缺點。因此本文主要分為兩部分，第一部分，設計跑道型激震器作為激振輸出，探討激震器之尺寸參數與氣隙磁通密度之收斂關係，使激震器能有效率地使用，最後歸納各尺寸參數之影響，建立完善的磁通資料庫，提供磁通之快速推估方法，以減少大量的電腦分析時間。第二部分，將跑道型激震器運用在三種常用長寬比之狹長板上，利用建立之磁通資料庫，探討激振器尺寸參數與聲壓曲線之關係，以期望得到最高聲壓感度或最低中音谷落差。最後，實作出跑道型激震器系統，經由實驗驗證，此設計準則可改善狹長型揚聲器之中音谷、提高聲壓感度，並搭配激振器外加磁式方法再次提升其聲壓感度。

This thesis aims to investigate the effects of exciting location on the sound radiation behavior of long flat-panel loudspeakers. In response to the current trend of flat electronic products, the speakers need to be long and narrow. When the speaker becomes narrow, the small width of the radiating plate will limit the size of the conventional circular transducer. The sound pressure level (SPL) of the speaker will become low and a major SPL dip in the mid frequency range may be incurred. In this thesis, the contents are divided into two parts. In the first part, a track-shape exciter is designed. The air-gap magnetic flux densities for different dimensions of transducer components are determined to find the optimal exciter design. Next, establish the magnetic flux database to provide a fast magnetic flux estimation method to reduce the large amount of computer time. The second part is about the use of the track-shape transducer to excite plates with different aspect ratios. The optimum transducer parameters for obtaining maximum SPL or minimum major dip in mid frequency range are determined. A number of loudspeakers are fabricated and tested to verify the proposed design procedure. Finally, a set of design guidelines for improving the SPL curves of different long rectangular flat speakers is proposed.

目 錄
中文摘要 i
英文摘要 ii
誌謝 iii
目錄 iv
表目錄 vi
圖目錄 vii
一、緒 論 1
1-1 前言 1
1-2 文獻回顧 1
1-3 研究方法 3
二、應用理論與有限元素分析 4
2-1 一階剪變形平板理論 4
2-1-1 位移與應變 4
2-1-2 應變與應力 5
2-2 磁性物理名詞基本定義 6
2-3 勞倫茲力 7
2-4 理想磁路 8
2-5 揚聲系統有限元素分析與聲壓計算 9
2-5-1 揚聲板數學模型 9
2-5-2 模擬元素的選擇 10
2-5-3 模型建立步驟 10
2-5-4 ANSYS模擬分析中各參數的取得 10
2-5-5 材料常數的給定 13
2-5-6 聲壓的計算及應用 13
2-6 激振器靜態磁場分析 14
2-6-1 材料常數與模擬元素 14
2-6-2 二維有限元素分析 14
2-6-3 三維有限元素分析 15
2-6-4 磁通密度分析與實驗值驗證 15
第三章 跑道型激振器之激振力探討 17
3-1 音圈線徑的選用 17
3-2 氣隙磁通密度分布 17
3-3 導磁片厚度 18
3-4 激振器高度與磁通收斂之關係 18
3-5 激振器長寬比與磁通收斂之關係 19
3-6 磁通密度之快速推估 19
3-7 激振器外加磁體之磁通增強探討 20
3-8 激振器外加磁體之實作應用 20
第四章 製作及實驗程序 22
4-1 平面揚聲器之各項組件製作 22
4-1-1 揚聲板之製作 22
4-1-2 跑道型激振器與外加磁體之製作 22
4-1-3 跑道型音圈之製作 23
4-1-4 懸邊之製作 23
4-2 平面揚聲器之組裝 24
4-3 揚聲器各項實驗程序 24
4-3-1 阻尼量測實驗 24
4-3-2 聲壓量測實驗 25
4-3-3 阻抗量測實驗 26
4-3-4 單體參數量測實驗 26
4-3-5 磁通密度量測實驗 26
第五章 結果與討論 28
5-1 分析與實作驗證 28
5-2 尺寸設計流程簡介 28
5-3 長寬比5狹長板之聲壓探討 29
5-4 長寬比10狹長板之聲壓探討 29
5-5 長寬比15狹長板之聲壓探討 29
5-6 聲壓分析總結 30
(1)聲壓感度探討： 30
(2)中音谷探討： 30
(3)設計流程圖： 32
(4)應用實例搭配碳纖加勁： 33
5-7 狹長型揚聲器之實作改善(1) 33
5-8 狹長型揚聲器之實作改善(2) 34
第六章 結論與未來研究方向 35
6-1 結論 35
6-2 未來研究方向 36
參考文獻 37

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