新型 LCD-TV LED背光模組驅動電路之研製

New LCD-TV LED Backlight Driver Circuit Module Design

廖得志(Te-Chih Liao)

指導教授 ： 王仲淳

元智大學/電機通訊學院/電機工程學系/碩士(2011年)

摘要

中文摘要

在節能減碳的環保共識下，較傳統背光元件( 如CCFL )更低消耗功率的 LED 已成為 LCD TV 新一代的背光源趨勢。相較於 Monitor 的應用， TV 由於尺寸較大，所以需要更多串列 ( String ) 的 LED 以達到其所需的背光亮度，而多串列的 LED 控制首先遇到的就是各串列間的電流平衡問題，不平衡的串列電流將造成亮度的不平均，進而影響畫面品質。如何在兼顧成本下達成各串列的電流平衡成為 LED 驅動設計工程師的挑戰。
傳統多組交流負載驅動 [如 CCFL、EEFL ( External Electrode Fluorescent Lamp 外置電極螢光燈) 等] 常連接被動元件於各組交流負載與交流電源輸入端之間，如此可達到多組交流負載電流平衡之均流效果。
本論文針對60吋 LED TV 提出一個功率損耗小，成本較廉價 LED 驅動電路。以被動元件應用於平衡多組直流負載電流之連接方式，做出 LCD-TV LED 驅動電路雛型，並量測數據及波形。交流電源透過整流線路的連接，可提供直流負載所需之直流電源。利用被動元件的連接可獲得各組直流負載間電流平衡之均流效果。本論文針對利用 LLC 諧振式轉換器加上 ”多組直流負載之電流平衡供電電路” 做整合設計。新型 LED 驅動模組主要目的在於提供更為廉價之電流平衡供電電路。利用不同於傳統的線路架構，使每一組直流負載的電流平衡且發光亮度相同，更使電路功率損耗小且電路運作效率高。相對使用較少的元件且電路複雜度低，並可節省大幅的成本。對新型 LED 均流線路加以探討並實際量測。

關鍵字

背光元件 ； LED 驅動 ； 電流平衡 ； 諧振式轉換器 ； 多組直流負載。

並列摘要

ABSTRACT

In the carbon reduction of environmental consensus, unlike the traditional backlighting elements (such as CCFL), the lower power consumption of the LED has become a new generation of LCD TV backlight trend. Compared to the application of monitor, TV as a larger size, they need more strings of the LED backlight modules to achieve the required brightness of the LED control and on it’s multi-serial LED strings. The first problem is the current imbalances will be encountered among LED strings. The imbalance will cause the serial current uneven brightness, and thus the image quality. How to reach a balance under the given cost and getting the current balance among the LED strings, will be a challenge to for LED driver designers.

Conventional AC load multiple drivers [ such as CCFL, EEFL ( External Electrode Fluorescent Lamp ), etc. ] often connected passive components in each group sharing the loads among AC power input, so one can achieve multiple AC load flow with current balance.

This thesis proposes a lower power loss and cheaper method LED driver module for a typical 60” LED TV. For balancing the multiple LED strings, the LCD-TV LED driver circuit prototype design with passive components used in the DC load current connection. In addition, the circuit outputs data and waveforms were also measured. The AC power connecting with a rectifier can provide the DC power for the DC loads. By the connection of passive components, it will get the current balance among the DC loads.

This thesis uses a LLC resonant converter design integrated with "A power supply with a H- balance LED driver for the multiple DC loads." The main purpose of the new power module for LED driver is to provide a cheaper and also efficient power supply circuit for current balance. Different from the traditional with linear structure, the new design can have current balance in each group of DC loads and the same brightness, the lower power consumption and high efficiency. The new design has relatively few components and low complexity, and substantial cost savings. With the actual measurements, we will measure and evaluate the performance of the new LED driver design with current balance circuits.

並列關鍵字

Multiple DC Loads。 ； Backlight Components ； LED Driver ； Current Balance ； Resonant Converter

參考文獻

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