臺灣博碩士論文加值系統

隨著產業的快速變動，近年來筆記型電腦與可攜式資訊產品不斷地推陳出新，使得液晶顯示器的需求量持續上升，同時也帶動了背光源的需求。本文提出一個以FPGA(Field Programmable Gate Array)為基礎的液晶顯示器背光系統開發，採用全橋式諧振換流器架構來驅動冷陰極燈管，並以FPGA作為系統控制核心，取代市售的CCFL(Cold Cathode Fluorescent Lamp)驅動晶片。在脈波寬度調變控制方面，採用零電壓切換，可減少開關導通所造成的損失。在調光控制方面，採用低頻脈衝調光來達到亮度明暗的控制，並利用另一種脈衝密度調變之調光方式，改善低頻脈衝調光控制在調光操作期間燈管會重覆點滅的缺點，以延長燈管的使用期限。最後，以數位的方式實現比例積分(PI)控制器，完成背光系統的全數位控制。

The proliferation of laptop and notebook computers places an ever-increasing demand on display technology, since high resolution and contrast are required to run today's graphics based programs. Nowadays, most of current LCD displays use CCFL backlighting because it satisfies the requirements on display performance, size, and efficiency.
In this thesis, an FPGA-based driving system for LCD backlight is presented. The proposed system consists of a switch-mode full-bridge inverter power stage operating in zero-voltage-switching (ZVS) condition to increase the conversion efficiency and an FPGA-based digital controller. In this thesis, low frequency dimming control and Pulse Density Modulation (PDM) dimming control are both proposed to regulate the brightness of lamps. The method of Pulse Density Modulation dimming control can mitigate the drawback of re-spiking problem of low frequency dimming control. At last, the full-digital control of a backlight system is accomplished by implementing the PI controller in digital way.

摘要 I
Abstarct II
誌謝 III
目錄 IV
圖目錄 VII
表目錄 X
第一章 緒論 1
1.1研究背景與動機 1
1.2論文大綱 3
第二章 冷陰極燈管的電氣特性 4
2.1背光源的種類介紹 4
2.2冷陰極燈管的發光原理 6
2.2.1燈管結構 6
2.2.2氣體放電 7
2.3冷陰極燈管的特性 8
2.3.1伏-安特性曲線 8
2.3.2冷陰極燈管之等效電路 11
2.3.3影響冷陰極燈管亮度的因素 11
2.4結論 15
第三章 液晶顯示器背光源驅動架構 16
3.1諧振網路簡介 16
3.2背光源驅動電路之換流器架構 20
3.2.1電流饋入推挽式並聯諧振換流器 20
3.2.2半橋式串聯諧振換流器架構 22
3.2.3全橋式相移調變換流器架構 23
3.3燈管調光控制 24
3.4結論 26
第四章 冷陰極燈管驅動電路架構 27
4.1全橋式零電壓切換諧振換流器 27
4.1.1零電壓切換模式說明與數學模型推導 28
4.1.2諧振網路原理分析與設計 34
4.2回授補償控制器 37
4.3調光控制 38
4.4燈管開路保護電路 40
4.5硬體電路佈局(layout)考量 42
4.6結論 43
第五章 以FPGA為基礎之液晶顯示器背光源驅動系統 44
5.1 FPGA晶片及硬體簡介 44
5.2系統架構 45
5.3閉迴路控制 48
5.4程式流程 50
5.5低頻脈衝調光控制 52
5.6脈衝密度調變之調光控制 52
5.7數位PI控制器電路設計與模擬 58
5.8結論 60
第六章 實驗結果與討論 61
第七章 結論與未來研究方向 71
7.1結論 71
7.2未來研究方向 72
參考文獻 73

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