高轉速光碟機音源辨認暨噪音減低之研究

Noise Source Identification and Noise Reduction of High Speed CD-ROMs

林佑庭(Yu-ting Lin)

指導教授 ： 王照明 ； 張英俊

大同大學/工程學院/機械工程學系所/碩士(2005年)

摘要

光碟機在高速運轉下所產生的噪音，其來源有二。第一是因為光碟片本身高速運轉，使得週遭的氣流也跟著流動，光碟片受到週遭氣流而造成擺動的現象，因而產生噪音，稱為空氣動力噪。第二是因為光碟機主軸馬達在高速轉動時，與聯接基座產生的振動所引發的噪音，稱為結構振動噪音。如何透過實驗方法了解光碟機產生之音源辨認，以及提出有效、簡單的方法降低光碟機噪音與聲壓頻譜；最後利用田口法與灰關聯將品質量化，並預測最佳聲壓值，是本研究的重點。

本論文利用實驗方法確定光碟機在高轉速下，主要的聲壓來源位置在700Hz與1700Hz附近，其原因分別因為氣流穿越光碟機四周縫隙，以及氣流直接碰撞光碟機上方機殼所引起的聲壓。此外，運用田口方法與灰關聯探討多孔板各項因素對於聲壓減低之影響，以及探討改變光碟片與四周機殼間隙的大小對於光碟機聲壓的變化；結果發現，多孔板能抑制1700Hz的聲壓，並且最佳參數組可減低5.1dB；並且探討光碟片與四周機殼間隙時，其最佳參數組亦可減低4.8dB。

關鍵字

田口法 ； 音源辨認 ； 光碟機

並列摘要

This article is meant to discuss the CD-ROM noise when it is loaded with a disk with 2 noise sources. The first is the noise through flowing and this is exactly the sound pressure value assigned by the CD-ROM makers. The pneumatic noise passing to the ears of users is referred to as aerodynamic noise. This value can be measured under the rotation of CD-ROM. The second one is the noise caused by vibration when the CD-ROM is reading or searching the data. This vibration energy will be directly passed to the chassis shell of PC set and make the chassis become the noise amplifier. How to recognize the source of the sound pressure of the CD-ROM and using Taguchi method and grey relational theory find out the optimum parameter combination will the issues within this research.
In this research, it is confirmed that there are two sources of the sound pressure of the CD-ROM under the high rotational speed. On the 700Hz, the sound pressure is caused by the airflow going though front and back interstices of laser disc machine. On the 1700Hz, the sound pressure is caused by the airflow knocking the internal part of the shell of the laser disc machine. So the noise on 700Hz and 1700Hz belong to the aerodynamic noise. Besides, no matter what Taguchi method and grey relational theory, the optimum parameter combination which is used perforated plate of reducing the total sound pressure can reduce 5.1 dB. And the optimum parameter combination which the distances are changed between the disc and the shell around the laser disc machine of reducing the total sound pressure can reduce 4.8 dB.

並列關鍵字

CD-ROM ； Noise Source Identification ； Taguchi method

參考文獻

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