薄型光碟機氣體流場與結構耦合效應之研究

Abstract

薄型光碟機是目前筆記型電腦主要資料存取設備之一，降低它的整體體積及重量為當前薄型光碟機發展目標之一。然而隨著體積的減小，薄型光碟機內部之氣流與碟片間的耦合作用，容易造成碟片的顫振；隨著重量的降低，造成在高速運轉時引發碟片、讀取頭甚至整個機構體的振動，因而引起碟片資料讀取不良的現象。本文的目的即研究這些問題，並且尋求改善的方法。本論文使用有限分析法，分析薄型光碟機之流場和結構耦合之效應，模擬在不同轉速及流場外型下，光碟片變形大小。同時嘗試透過改變流場外型，以期改善碟片的振動量。 本論文研究結果發現，薄型光碟機內部流場及結構的耦合效應，會使碟片鉛直振幅由3擴大至125 。當碟片振幅在光碟機可伺服控制的範圍內時，並非影響讀取性能的主要因素，但當碟片振幅超過伺服控制的範圍時，讀取性能便減低。本論文之實驗量測結果發現，降低上蓋流場高度及增加上蓋流場粗糙度，確實能改善薄型光碟機之讀取性能。亦由模擬結果發現，降低上蓋流場高度及增加上蓋流場粗糙度，確實能改變流場的壓力分佈，因而降低碟片振幅，達到改善薄型光碟機讀取性能的目的。

Slim-type optical disk drives is one of indispensable data access device in laptop computers nowadays. Reducing its volume and weight is one of major objectives for the current slim-type disk drive development. With the reduction of its chest volume, disk rotation leads to airflow between the chest and disk such that the coupling between the airflow and structure may cause the disk to vibrate. With the weight decrease, high-speed disk rotation may cause the disk, the read and write pickup head, and even the whole structure to vibrate. Accordingly, it may result in poor condition of data access. This study carries out the finite element method to analyze coupling effects between flow and structure of the slim disk drive. We examine disk deformation by simulating different disk speeds and flow geometries. Moreover, we reduce the vibration of the disk by changing the flow field geometry. This study found that the coupling effects between the airflow and structure of the slim disk drive will enlarge the disk vibration amplitude from 3 to 125 . When the amplitude is within the servo control range of the slim disk drive, it is not a main factor that affects the read/write capability of the drive. However, when the amplitude exceeds the servo control range, the read/write capability degrades. Experimental results show that we can improve slim disk drive read/write performance certainly by reducing the height and enlarging the roughness of the top flow flied. Also from simulate results show that the pressure distribution of the flow varies by reducing the height and enlarging the roughness of the top flow field inside the drive. As a consequence, we decrease the disk amplitude and hence improve read/write performance of the slim disk drive.