光碟機讀寫頭動態及碟片除塵之研究

Abstract

近場光碟機讀取頭末端之飛行滑塊藉著稀薄氣體流場，飛行高度維持在碟片上方50 nm左右，利用近場光學的原理，使得雷射光聚焦能夠克服繞射極限，大幅提升存取密度。然而，飛行高度之變動深受本身結構震動、碟片和氣流擾動所影響。為了簡化懸吊組件和空氣軸承，本研究利用包含彈簧阻尼的系統模擬讀取頭滑塊在三個方向 (對焦、俯仰和滾轉) 的動態行為，並證實在近場光學儲存要求下，滑塊與碟片之近距離使得凡得瓦力與靜電力的效應益加顯著。此外，由於沾黏於碟片上的塵埃顆粒半徑甚至大於讀取頭飛行高度，故將其從碟片上去除在實用上值得考量。本研究探討碟片旋轉產生的離心力是否足以克服塵埃顆粒和碟片間的附著力，達到除塵的效果。本研究根據塵埃顆粒在碟片上之自由體圖，以及顆粒大小、碟片材質，計算灰塵脫離碟片的關鍵轉速。

A near-field optical disk drive uses near-field optics to read/write disk data with a flying height at about 50 nm. Effects of interfacial adhesive forces including van der Waals forces and electrostatic forces become more evident during the ultra-low flying. However, the flying height is affected by pickup head vibration, disk flutter, and air flow between the flying head and disk. The analysis model consisting of a simplified suspension and an air bearing model with springs and dampers in three directions (focusing, pitching and rolling) is used to simulate the dynamic behavior of the flying head. Simulation results with and without interfacial adhesive forces are compared. Moreover, because the flying height is often less than the radius of dust adhering to the disk surface, it is desired to remove particles from the disk surface. This study investigates whether the centrifugal force caused by high rotational speed conquers the adhesive force between dust and the disk surface. Simulation results with various particle diameters, disk speeds, and disk materials are compared.