3C產品聲場繞射分析-以筆記型電腦為例

在電聲設計分析中，常以類比電路法做為揚聲器電聲模擬的主要方法。類比電路法主要將揚聲器零件轉換成等效的電子元件，並且依據相對應的關係繪製成電路，再利用電子電路進行等效電路的分析。此分析的結果雖可以將揚聲器與音箱的聲學特性進行模擬，但類比電路法對於產品外型在聲場中所造成的聲音繞射卻無法進行分析。由實際量測結果得知，聲音傳遞過程中的繞射效應確實存在而使得分析的結果有誤差。LEAP Enclosureshop是揚聲器分析工具，雖提供了不同音箱設計的繞射分析，但卻不適用於3C產品複雜的外型上。為了分析並解決產品外型造成音波繞射的問題，本研究利用CAD建立3D產品模型，將此3D模型匯入LEAP模擬工具。再依據聲學的觀點，將腔體的複雜幾何形狀利用CAD進行體積精確的計算，將結果於LEAP軟體中以相對應的幾何形狀、參數以及分析的條件輸入。最後利用LEAP不同條件的分析方式進行聲場的模擬，並且與實際量測結果做為驗證。此方法最大的優勢在於了解不同產品造型設計上對聲音繞射的影響，提供3C產品聲學設計時的參考價值。

關鍵字

微型揚聲器；聲繞射；聲場模擬；筆記型電腦

並列摘要

In the electro-acoustic design and analysis, the electro-acoustic simulations by analog circuit method are usually apply on the speaker, the analog circuit is mainly converted the speaker parts into equivalent electronic components, and according to corresponding relationship of parts drawn into this circuit, and then using analog circuit software to analyze. Although analysis results from this method can be simulated the electro-acoustic characteristics of the speaker, but cannot simulate the product shape diffraction effect in the sound field. Also learned from measurement result, the sound diffraction indeed affects the measurement result. The LEAP Enclosureshop speaker analytical tools provided diffraction analysis of different speaker box design, but cannot apply on the 3C product appearance design. To solve the diffraction problem of 3C products, this research utilized CAD software to create 3D models and import to LEAP software. According acoustics view to separate complex geometry of cavity and volumetric calculation by CAD software, the result will be input into LEAP software to calculate and perform sound simulation in different condition by LEAP. The advantage of this simulation method is to understand the product appearance design on sound diffraction impact, the simulation result also provides to engineer reference data when electroacoustic products design.

並列關鍵字

Microspeaker ； Sound diffraction ； Simulation in sound field ； Notebook

參考文獻

[2] R. G. Kouyoumjian & P. H. Pathak. "A Uniform Geometrical Theory of Diffraction for an Edge in a Perfectly Conducting Surface," Proc IEEE ( S0018-9219) , 1974, Vol. 62 No. 11 : 1448.

[4] H. F. Olson, Elements of acoustical engineering, First edition, New York, D. Van Nostrand company Inc, 1940, pp. 17-18.

[5] H. F. Olson, "Direct Radiator Loudspeaker Enclosures," An AES paper Presented, 1950. Octorber 27.

[6] H. F. Olson, Elements of acoustical engineering, Second edition, New York, D. Van Nostrand company Inc, 1957, pp. 17~24.

[7] M. Fresse, An experimental study in near field sound diffraction, McGill University, Montreal Canada, 1966.

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3C產品聲場繞射分析-以筆記型電腦為例

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