LED間斷式驅動對色度表現之影響;Effects of On-off Driving on Colorimetric Behaviors for LEDs

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题名:	LED間斷式驅動對色度表現之影響;Effects of On-off Driving on Colorimetric Behaviors for LEDs
作者:	李祐銘;Yo-Min Lee
贡献者:	光電科學研究所
关键词:	間斷式驅動;色度;發光二極體;PWM;colorimetric;LED
日期:	2007-07-10
上传时间:	2009-09-22 10:33:51 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	近年來LED的應用越來越廣泛，但是LED的熱效應問題始終無法得到很好的改善方式，熱效應會影響LED的壽命、色度、亮度。為了改善LED熱效應問題，其中一個方法就是以間歇式做為驅動。本研究主要是針對LED以間歇式驅動所產生的色度偏移現象做探討。當LED以間歇式驅動時，在狀態切換的過程會造成色度偏移，為了量測此色度的偏移量，本文利用白光、紅光、綠光、藍光LED，以光譜儀進行量測，將光譜資訊轉成CIE xy色度座標，發現此偏移量與電流大小有關。同時，利用RGB三色LED模擬混色D65光源，發現在狀態切換過程的中，CIE色度座標最大偏移超過0.09，與D65色度座標附近的MacAdam橢圓比較，人眼不可分辨的範圍大約是0.002之內，因此，這樣的色度偏移量是相當嚴重的情形。All the technologies related to the development of the LED (lighting-emitting diodes) have been rapidly evolved for the applications both in the general lighting and the display technology. However, before it successes, there are still some critical concerns to be overcome, especially the heat dissipation. One most common recommendation is to drive LEDs with on-off intermittent type of the current sources, for example the pulse-width-modulation (PWM) driving. In this work, it is focused on the chromaticity shift caused by the on-off intermittent type of the driving on LEDs. As expected, the chromaticity will do shift during the transition of each on and/or off instance. Concludingly, the CIE xy chromaticity does have deviation as much as 0.09 during the transitions. The resultant chromatic shifts are found to be greatly larger than the minimal sensitivity of the human vision, 0.002.
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