光資訊儲存系統之微細讀寫機構與控制技術研究(III)

Abstract

光資訊儲存系統已逐漸成為大量數位資料存取之重要工具，而光學讀取頭乃是光資 訊儲存系統技術發展中之關鍵技術，要求其輕量且體積小巧。為了達到25GB 高密度 藍光碟片的資訊存取且兼容於前期CD/DVD 光碟片，具有780/650/405 nm 光波長之光 源及光學鏡片模組須同時設計在目前藍光讀取頭中，如此設計之裝置增加光學讀取頭 體積及重量。因此如何縮小光學讀取頭尺寸為發展高密度光資訊儲存系統之重要課題。 本研究計畫主要目的在發展微細光學讀取頭的設計方法，研究將780/650/405 nm 光 波長之光源模組、光學鏡片模組及光偵測電路等組件與光學讀取頭分離，而以光纖傳 輸雷射光至物鏡，聚焦光點於碟片上，以讀取資料。此設計方式有兩大優點：一、減 少光學讀取頭體積及重量，由於光學讀取頭致動件部份只留下物鏡、光纖、線圈與磁 鐵，大幅縮減光學讀取頭外型尺寸。二、光源模組、光學鏡片模組及光偵測電路成為在 電路板上之固定件，因此其零組件無需特別縮小以能置入光學讀取頭中，使國內相關零組 件(尤其在藍光二極體模組)供應商無需受限於各光學讀取頭生產廠規定之尺寸。 本研究計畫分為三年執行，第一年先建立光纖傳導系統、架構三波長雷射光源與其功 率控制方式，研究不同光波長經由物鏡聚焦至碟片之光點及功率。本計畫執行第一年利用 雙軸向翹曲機構運動模式，經模態分析與模擬，成功設計出微型光學讀寫機構及VCM 進行光點聚焦與循軌驅動，並且重新針對控制方式做設計分析。第二年將研究與設計光 纖與物鏡整合之驅動與數位伺服控制系統，並分析機構動態特性，以讀取光碟片上之凹點 信號。第三年將設計微聚焦物鏡、光纖耦合物鏡、光學感測器電路及32-bit DSP 控制器 以整合光纖讀取頭系統之訊號讀取與控制方式，以期能完整進行光碟片信號讀取控制與 系統分析，並引入國內發展之藍光二極體雷射模組。 本計畫研究微細光學讀取頭設計方式，縮減傳統光學讀取頭之體積、重量及增加光 傳導效率。而計畫執行之成果，可進一步將此微細光學讀取裝置朝向商品化設計應用研 究。

Optical information storage systems are becoming an increasingly important device for retrieving and storing digital data. One of the key technologies in optical information storage system to read/write data is the optical pickup head which demands compact and light-weight. To satisfy the latest 25GB high density Blu-ray optical disc drive and needs for backward compatibility, a BD/DVD/CD compatible pickup head has developed with laser light source modules of 780/650/405 nm wavelength implemented in the optical pick-up head, which eventually increased the size and the weight of pickup head. To minimize the volume of optical pickup head is a significant issue in developing high density optical information storage system. The main purpose of this project is to develop an optical pickup head design which separated the 780/650/405nm light source modules, beam splitter, and photo detector from pickup head main unit and using an optical fiber transferred the laser beam from fixed laser diode module to objective lens and read the data in optical disc. Two main advantages in this design are considered: 1. Reduce the size and the weight of pickup head, since only the objective lens, coil, magnetic, fiber are kept in the pickup, it will shrink the total dimension of pickup unit. 2. As the light source modules, beam splitter, and photo detector are fixed in the PCB, there is more space for the components, no need to meet special size-reduced specification. Also the maintenance of laser modules will be easy and flexible. This project will be carried out in 3 years. Micro-optical components integration, new seesaw swing-arm type actuators design are the first year’s main target for the miniaturization of optical drives. The second year efforts will focus on designing the driver and the servo control system of miniaturized optical module including objective lens together with fiber, and its mechanical structure dynamic analysis. An adaptive ZPETC design for dual-stage actuator is designed for high speed focusing in miniaturized ODD. The parallel construction of dual-stage actuator provides a fine focusing solution to overcome the signal actuator coarse focusing. A design technique is studied to inverse the transfer function of feedback closed loop and to use the ZPECT method to reduce the phase lag and delay. The feed-forward controller will be added to seesaw swing arm VCM drive and piezo plate control input in addition to other servo input signals, and the effective adaptive ZPETC closed loop algorithm will be established. Preliminary simulation results showed that the signal of the FF and FF-PZT controller is matched to the input signal and work well for controlling the seesaw/PZT dual-stage swing-arm actuator focusing operation in mini-ODD. 表 C011 共 2 頁第 2 頁 The third year research will be focused on two main items: Firstly, design the micro objective lens, fiber coupling lens, optical detector system and 32-bit DSP control board to form the full fiber optical micro pickup head system to read the signals from simulation disc. Secondly, analyze the dynamic stability of reading disc data and integrating this design with the system solution of optical drive DSP IC. By constructing the apparatus in this project, the size; the weight; and the characteristics of an optical pickup head can be improved. The result and the delivery of project can be further implemented for commercial applications.