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  • 學位論文

導音管風切音及音膜特性的理論分析與實驗量測

Theoretical Analysis and Experimental Measurements on the Characteristics for Diaphragm and the Noise of Port

指導教授 : 馬劍清
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摘要


隨著科技持續的進步與發展,人們對於揚聲器等產品的品質要求愈來愈高,尤其以電聲產業近年來的迅速發展,使電聲產品朝向輕薄短小,並針對攜帶方便的特點為發展方向。盡管揚聲器的作動原理相當簡單,但也是一項歷久彌新的技術,要生產具備好音質又低失真的完美揚聲器,卻是個極為艱鉅的任務,況且對聲音的偏好亦因人而異,因此如何生產出能滿足不同使用者需求的揚聲器,絕對是個值得投入心力研究的課題。 本文針對振膜與導音管材料結構對於揚聲器系統動態特性的影響分析與量測作深入探討,內容主要分為兩個部份,首先是研究關於音膜材料之機械特性,主要藉由實驗量測的方式,並設計夾具提供良好的邊界條件,以奈米壓痕與氣壓推動試驗分別測量不同厚度、材料的音膜之彎曲剛性,且以雷射位移計量測音膜的動態時域訊號,藉由振動學原理求得不同頻率下不同厚度、材料之阻尼比。 第二部份將針對低音反射式音箱產生寬帶噪音的問題進行實驗量測與特性分析,首先找出因系統影響導致風切音強度較強之頻帶,並以此為激振頻率,再以有限元素軟體模擬不同管徑、長度下的風切音強度,進而得到設計導音管的大方向,再以實驗驗證有限元素軟體的正確性,並比較不同尺寸導音管之實驗量測、模擬、駐波理論之共振頻,最後改變導音管的幾何結構,分別以有限元素軟體預測及實驗驗證,試圖找出有效將低風切音強度的方法。

並列摘要


With the continuous improvement and rapid development of technology, the demand for high quality of loudspeaker are increased. Electro-acoustic industry particularly focus on the development of speakers, to make products much smaller, thinner, and easy to carry. Though the working principle of speakers is considerably uncomplicated and the technology of speakers has been developed for a long time. However manufacturing a high-quality speaker with sweet-sounding voice and low distortion is still a difficult issue. Preference for voice is distinct for people, thus the task about designing a perfect speaker to satisfy different users is worthy of being discussed. The main purpose of this research focuses on theoretical analysis, numerical analysis and experimental measurements on the influence of dynamic characteristics for diaphragm, and port in loudspeaker system. The content of this thesis is divided into two parts. The content of this thesis is ranged into two parts. The first topic of this thesis is to The first topic of this thesis is to research the mechanical characteristics of materials for diaphragms by experimental measurement, and design fixtures to provide fine boundary condition. The stiffness of the diaphragm is measured by the Nano-indentation and air pressure pushing of the thin film for diaphragms. The damping ratio of the diaphragm in distinct exciting frequency is determined by measuring the dynamic signals of the different thickness and material of diaphragm on the basis of vibration theory by laser displacement sensor. The second topic of this thesis is to perform the analysis to appraise the characteristics of broad-band noise generated from small bass-reflex loudspeaker. To begin with, we find the Bandwidth with stronger noise from system to obtain exciting frequencies. The noise strength of different diameter and length for port by the finite element analysis, consequently we can get principal direction to design port. Furthermore, the correctness of simulation is verified by experiment. We compare resonant frequency of chuffing for different port by experiment, simulation and standing wave theory. Finally, we change the shape of port to attempt to reduce the noise strength.by above-mentioned step.

參考文獻


[2] 蔡長安,劉興華, "微型喇叭音箱及出音孔之設計與分析," 碩士論文, 車輛工程研究所, 臺北科技大學, 2007.
[1] 林致達,劉興華, "微型喇叭聲學特性測試與模擬," 碩士論文, 車輛工程研究所, 臺北科技大學, 2006.
[10] 趙浚瑜,馬劍清, "超磁致伸縮材料、層狀壓電壓磁複合材料及磁場動圈式揚聲器動態特性之分析與量測," 碩士論文, 機械工程研究所, 臺灣大學, 2014.
[11] 吳柍蓁,馬劍清, "振膜、導音管及調音布對於揚聲器系統動態特性的影響分析與量測," 碩士論文, 機械工程研究所, 臺灣大學, 2015
[15] Small, Richard H. "Vented-Box Loudspeaker Systems--Part 1: Small-Signal Analysis." Journal of the Audio Engineering Society 21.5 (1973): 363-372.

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