臺灣博碩士論文加值系統

本研究之目的主要為分析並探討改變振膜皺摺角度( corrugation angle )之情況下，此一因素對頻率響應之影響。以及動圈式微型揚聲器( Moving-coil Type Micro-speaker )在流體和固體耦合( fluid-structure interaction )之情況下分析。本文探討結合動態、電磁、聲學效應之下，分析微型揚器之振膜在不同的皺摺角度時，其頻率響應圖之曲線分佈，在論文最後亦會提出討論造成此部份之曲線趨勢背後之物理因素。此外，為了使模擬微型揚聲器之頻率響應圖與實驗結果在高頻部份相互得到驗證，在此，本研究亦提出了微型揚聲器振膜與其前後音腔之流-固耦合作用分析。

In this study, the simulation results of the diaphragm of the micro-speaker considered with different corrugation angles, 15, 45, 75 degrees, respectively, are presented in the study using dynamic analysis, which includes electromagnetic, mechanical, and acoustical modeling for respective subsystems. The frequency responses of the three cases can be obtained and discussed the discrepancy of the results. On the other hand,　the moving-coil type micro-speaker considered with fluid-structure interaction of the diaphragm and the air within the micro-speaker is also investigated. In order to predict the response of the experiment data at high frequency, the air enclosure within the micro-speaker is taken into account. To simplify the building process of finite element model of the air enclosure, the corrugated profiles of the diaphragm is neglected. The simulation result can be obtained via ANSYS harmonic analysis and compared with the experiment data.

摘要 I
Abstract II
謝誌 III
Table of Contents IV
Figure Captions VI
Table Titles VIII
Nomenclature IX
1. Introduction 1
2. Mathematical Modelings 3
2.1 Dynamic Analysis on Micro-speaker 3
2.1.1 Radiation Mass 3
2.1.2 Effective Mass of Vents 4
2.1.3 Sound Pressure Level 5
2.2. Acoustic Fluid Fundamentals 5
2.2.1 Governing Equations 5
2.2.2 Discretization of the Lossless Wave Equation 6
2.3 Derivation of Acoustics Fluid Matrices 8
2.4 Absorption of Acoustical Pressure Wave 10
2.5. Acoustic Fluid-Structure Coupling 11
3. Simulation Results and Experiment Verification 14
4. Conclusions and Future Works 16
References 17
Figures 19
Tables 33

Figure Captions
Figure 1 The cross-sectional view of the moving-coil type micro-speaker. 19
Figure 2 Corrugated profiles of the diaphragm of the micro-speaker. 20
Figure 3 The experimental Equipment for measuring sound pressure level of the micro-speaker. 21
Figure 4 The FEM model of the vibration system of the micro-speaker: (a) side view, (b) top view, and (c) bottom view. 22
Figure 5 The finite element models of diaphragm with different corrugation angle: (a) without corrugation angle, (b) Corrugation angle for 15 degrees, (c) Corrugation angle for 45 degrees, (d) Corrugation angle for 75 degrees. 24
Figure 6 The finite element model of the air enclosure within the micro-speaker. 25
Figure 7 The simulation results and experimental data of the diaphragm with different corrugation angle. 26
Figure 8 The simulation results and experimental data of the micro-speaker with air enclosure. 27
Figure 9 The FEM model of the vibration system of the micro-speaker with the effective mass of the acoustical effect which is transformed into concentration mass. 28
Figure 10 The mode shape causes anti-resonance of the diaphragm with corrugation angle of 75 degrees. 29
Figure 11 The displacement after applying a force to the nodes located at the intersection of diaphragm and VCM. 31
Figure 12 The whole analysis procedure of the micro-speaker. 32

Table Titles
Table 1 The material properties of the diaphragm of the micro-speaker. 33
Table 2 The material properties of the air. 34

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