本文針對液晶顯示器採用發光二極體之背光源，提出一個新型發光二極體驅動電路。將返馳式轉換器以三繞組輸出，取代三組直流對直流轉換器，來驅動紅、綠、藍發光二極體光棒。在調光控制下，藉由調整返馳式轉換器開關的導通率，輸出適中電壓給紅、綠、藍發光二極體，使輸出電流峰值維持在一定誤差範圍內。個別控制三組調光開關導通率，來控制三原色發光二極體的亮度。並在電路調光範圍內，改變三原色發光二極體之平均電流比例，使色溫調整範圍可達到液晶顯示器色溫操作要求。本文所提出的電路和市售之傳統驅動電路比較後，證實能精簡電路和有較高之電路效率。

This thesis proposes a novel driving circuit of the RGB light emitting diodes (LEDs) for the back-light source of the liquid crystal display. In stead of employing three dc-to-dc converters, a fly-back converter with three secondary windings is used to drive RGB-LED light bars. By adjusting the duty-ratio, the fly-back converter provides compromised voltages to RGB-LEDs in accordance with the operating modes of dimming control, so as to retain current magnitudes within the acceptable values. LEDs of three colors are dimmed by regulating the duty-ratios of three active power switches individually. By changing the ratio of the average currents of the three primary color LEDs, the color temperature range of driving can reach the requests of dimming control. As compared with a consumer product using the conventional driving circuit, the proposed circuit is obviously much simpler with less components and a higher efficiency.

中文摘要 I
英文摘要 II
目錄 III
圖表目錄 V
第一章 簡介 1
1-1研究背景 1
1-2研究動機 4
1-3論文大綱 6
第二章 三原色LED結構與傳統驅動電路 7
2-1三原色LED光譜 7
2-2 LED光棒之串並聯 10
2-3電流平穩 12
2-4 LED傳統驅動電路 15
第三章 LED背光源驅動電路 17
3-1 三繞組輸出之返馳式轉換器驅動電路架構 17
3-2 驅動電路 19
3-2-1電路運作原理 19
3-2-2電路工作模式 22
3-3 輸出電壓控制 28
3-3-1電路參數 28
3-3-2 RGB混光電阻權重設計 30
第四章 電路特性量測與分析 33
4-1電流平穩之操作範圍 33
4-2調光特性 34
4-3色溫調整特性 37
4-3-1電流比例 37
4-3-2色溫調整 40
4-4電路效率 41
第五章 結論與討論 42
參考文獻 43

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