適用於LCD-監視器之LED背光電路模組設計

DESIGN OF LED BACKLIGHT CIRCUIT MODULE FOR LCD-MONITOR

吳志宏(Chih-hung Wu)

指導教授 ： 蔡明傑

大同大學/電機資訊學院/電機工程學系所/碩士(2010年)

摘要

本文提出一個 LED 陣列驅動電路模組，可使用於 LCD-監視器的背光模組及照明系統，依照定功率曲線圖，計算出最佳電壓和電流，並決定出適合的 LED 陣列。文中使用返馳式 (Fly-back) 轉換器做為交流轉直流電源供應器，以電流迴授模式的脈波寬度調變方式得到穩定輸出定電壓(12V)，再使用升壓型（Boost）轉換器升壓，依 LED 陣列迴授決定驅動電壓，以電流鏡方式得定電流輸出，使得每一列 LED 電流相同，減少 LED 之間的輝度差異，並使用動態選取功能，來達到每一陣列LED可以同時亮起。本線路特點在於模組化設計，可應用於多種尺寸的LED 背光模組，皆能產生出合適的驅動電壓與定電流，以達共用之目標。

關鍵字

調光 ； 動態選取 ； 電流鏡 ； 脈波寬度調變 ； 模組化 ； 定功率曲線 ； 返馳式轉換器 ； 升壓型轉換器

並列摘要

A LED arrays driver circuit of module is proposed, and is used in the backlight of LCD-monitor and illumination system. As constant-power dissipation curve, calculate the optimal voltage and current and determine the appropriate LED arrays. With Fly-back converter to be a AC to DC power supply and get the fixed voltage (12V) by pulse width modulation (PWM) of current feedback mode, then adopt the Boost converter to arise the voltage. Depend on feedback of LED arrays and generate the driver voltage. In order to reduce the luminance difference between each LED, this makes stable current of LED arrays by current mirror. And using the dynamic select function let LED arrays light at the same. The feature of this circuit is module design that applies various LED backlight models and generates the applicable voltage and stable current then achieve the common-design purpose.

並列關鍵字

constant-power dissipation curve ； Dimming ； dynamic select ； PWM ； module ； current mirror ； Fly-back converter ； Boost converter

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