以PID 方法用於近場光碟機讀寫頭飛行高度之控制

Abstract

本論文之目的在探討光碟機之飛行高度控制。近場光碟機由於使用近場光學理論 於光碟機讀寫頭之設計，故而可突破以往之設計限制大大提升儲存密度及容量，為能有效應用近場光學理論，光碟讀取頭之飛行高度需降至次波長之距離，在如此微小的飛行高度下，碟片表面與物鏡的碰撞風險將大幅增加。本研究之控制器使用美商國家儀器所生產之單卡式RIO 嵌入系統sbRIO-9602，以PID 方法對光碟機讀取頭執行迴授控制，以減少碟片運轉時的振動與偏擺所造成之飛行高度變化，使物鏡與碟片表面之飛行距離可維持在所需之關鍵高度以下，並同時避免碰撞風險。在控制實驗中，將讀寫頭飛行高度成功降低至750 奈米。

This thesis uses a PID controller to control the pickup head flying height in a near-field optical disk drive. Near-field optical theory applied to an optical pickup head can improve optical disk drive storage capacity. In order to achieve near-field optical recoding, the distance between the objective lens and disk surface, i.e. the flying height must keep within the range of sub-wavelength. In such small flying clearance, head disk crash risk will become higher and higher. This study uses National Instrument sbRIO-9602 embedded device using closed-loop control voice coil motor by the PID method to reduce the flying height variation induced by media waviness under critical clearance. The result successfully avoids the pickup head to crash media surface and reduces the flying height to 750nm.