具條狀支撐方型平面揚聲器之研製

Abstract

本文重點分兩部份，第一部份為揚聲器彈性支承的研製，其中包括支承材料的選擇、支承材料的幾何形狀、支撐結構的製作及其噪音的克服。使揚聲器振動系統的第一個自然頻率 降低，以降低揚聲器聲壓的起始頻率、提昇整體振動板在較大的振幅下也能穩定的往復運動，以提昇揚聲器在低頻的發聲效率，並避免因為不穩定而產生的噪音、降低在研製過程中所增加的重量，使整體揚聲器的發聲更有效率。符合如此條件的彈性支承，便能讓小面積平面振動板的揚聲器在低頻也能有好的表現。第二部份針對使用複合材料結構來加勁振動板，因為振動模態的變形導致中音谷的產生，本文先以實驗驗證有限元素分析軟體ANSYS分析的模型，模擬比較純巴桑木振動板和不同區域不同加勁寬度碳纖維三明治結構振動板揚聲器的聲壓曲線，最後討論找出中音谷落差最小、加勁寬度最小的加勁方式，並以實驗驗證之。

Two parts are discussed in the thesis. First part is the fabrication of beam-type elastic suspensions of loudspeakers, including the choices of supporting materials and the geometrical shapes of the elastic supports. The purpose of the use of the beam-type elastic supports in the design and fabrication of the speakers is that the speakers can have low first resonant frequency, the radiating plate can vibrate in a steady way, and the radiating efficiency in low frequency range is improved. Furthermore, the elastic supports are designed in such a way that the noise due to instability can be reduced, and the weight of the radiating plate can also be reduced. The purpose of elastic suspensions can make the flat- panel speaker with small area have good performance in low frequency. Second part is focused on the use of composite materials to stiffen the radiating plate so as to suppress the mid-frequency dip. In the design of the stiffened plate, the finite element software ANSYS is used to study the vibration of the plate. Different stiffened radiating plates are designed for simulating the SPL curves of the speakers. The speakers fabricated using the proposed method are tested to measured the SPL curves of the speakers. The experimental results are used to verify the feasibility of the proposed design of the speakers.