低電壓超快速聚焦液晶透鏡

Abstract

手機結合相機功能是近幾年手機發展的主要潮流。現今照相手機多是利用數位變焦以達到變焦的功能，影像品質並不如利用光學變焦。傳統光學變焦是透過設置一透鏡組，利用機械化移動透鏡間距離，控制其等效的焦距長度。然而此法需要足夠的空間容納眾多透鏡，且也有機械性損耗的問題。若要將傳統透鏡組結合至體積輕薄短小的照相手機裡，將面臨很大的挑戰。 本研究提出一種可調焦液晶透鏡，其特色是短聚焦反應時間及低操作電壓。裝置採用內電極配置，搭配中央控制電極並在電極之間旋塗上高電阻值材料，可以有效的使電能鎖在液晶層裡。同時，高電阻質材料也能提供在控制電極間平緩梯度的電場分布。和傳統液晶透鏡相比，此梯度控制液晶透鏡可將操作電壓從數十伏特降低至5伏特，配合過驅動方法，可將聚焦反應時間從三十秒降低至零點二秒。此種梯度控制液晶透鏡具有電力控制及可達成的光學變焦特性，不需機械操作，體積小，且耗電低聚焦反應時間短。十分適合結合至手機鏡頭模組中。

Cell phone combined with camera function is the main trend in recent years. Most camera phones in present day utilize digital zoom function to zoom in. However, the image quality using digital zoom function is worse than using optical zoom function. Conventional optical zoom function is achieved by mechanical moving lens in a zoom lens system. Zoom lens require some volume to contain lots of lens components and have mechanical damage issue in long-term use. Applying the conventional zoom lens in the camera phone is a great challenge. In this study, a tunable-focus liquid crystal lens exhibiting ultra-fast focusing and low operating voltage was proposed. The inside electrode configuration with a central controlling electrode is combined with a high resistance layer to conserve electric power efficiently. Moreover, the smooth gradient electric field distribution is maintained by the high resistance layer. Compared with conventional liquid crystal lens, this gradient driven liquid crystal lens (GD-LC lens) decreased the operating voltage from twenty more voltage to 5 voltages. And with using Over-Drive method, GD-LC lens decreased focusing response time from thirty seconds to 0.2 second. This GD-LC lens has unique characteristic such as electric tunable focus, no mechanical moving part, small volume, low operating voltage and short response time which is suitable for camera phones application.