利用磁預壓力之微型音圈馬達自動對焦致動器設計

Design of Miniaturized Auto-Focusing VCM Actuators with Using Pre-Compression Magnet Force

李鴻飛(Hong-Fei Li)

指導教授 ： 劉建聖

國立中正大學/工學院/機械工程學系/碩士(2014年)

摘要

在影像系統中，對焦是其中最重要的功能之一，通常需要機械式移動系統中一個或多個透鏡/鏡子來執行。隨著科技的進步，近年來將具有對焦或變焦功能的數位相機整合到手機裡，亦即相機手機的產品已經躍升為市場的主流，自動對焦致動器在相機系統中是基本配備，主要功能在於拍照時調整焦距，改善成像品質；應用在手機相機中則要求微型、高性能的自動對焦致動器，而音圈馬達因為有成本低、體積小及定位重複性高等優點，因此最適合用於手機相機模組中。
然而目前音圈馬達都是採用彈片開迴路式的設計，彈片開迴路式音圈馬達，卻有彈片製造組裝困難、耐摔性差及能耗不易降低的缺點。但隨著產品附加價值的提高以及消費者的消費型態的驅使下，設計手機相機模組用的自動對焦致動器時，必須考慮降低其成本、增進其耐摔性以及減少其能源消耗，以符合消費性電子產品的趨勢。因此，本文針對致動器結構上做改良，提出利用磁預壓力取代目前傳統彈片式手機相機致動器的預壓力結構，並做出雛型品驗證之對焦功能。實驗結果顯示，本文所提出利用磁預壓力的方法可替代目前市面上較普遍的彈片式音圈馬達，並設計出尺寸8.5x8.5mm音圈馬達致動器。

關鍵字

手機相機 ； 致動器 ； 音圈馬達 ； 磁預壓力

並列摘要

Focus adjustment is one of the most basic functionalities in all imaging and scanning systems, generally requires the mechanical motion of one or more lenses or mirrors within the system. In particular, a requirement exists for compact, high-performance auto-focusing actuators for the camera modules deployed in cell phones. The VCM actuator is the most promising module for cell phone camera applications due to its low cost, low power consumption, fast response, high repeatability, and small size. Accordingly, VCMs are ideally suited to the actuation of miniature cell phone camera modules.
To the best of our knowledge, the sold autofocusing VCM actuators for cell phone camera applications are based upon spring plates open-loop position control algorithms except for few designs. However, the spring plates have three chief drawbacks. Firstly it is difficult to manufacture and assemble the structure of the spring plates, thus they have their cost limit. Secondly the stiffness of the spring plates limits the power consumption with decreasing dimension of the VCM actuators. Thirdly the robustness of the spring plates against drop and shock is weak.Therefore, this study presents a newly designed autofocusing VCM actuator with a magnetic pre-compression force. The newly proposed design belongs to the category of open-loop position control. In the newly proposed design, the magnetic pre-compression force between the permanent magnets and the guide rods will replace the restoring force of spring plates used in the conventional VCM actuator with open-loop position control.
Experimental results show that the magnetic pre-compression force can replace the restoring force of spring plates in the studied case： 8.5x8.5 mm VCM.

並列關鍵字

cell phone camera ； actuator ； voice coil motor ； pre-compression force

參考文獻

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