相位控制之壓電式變壓器應用於背光反流器

Phase Controlled Piezoelectric Transformer Using in Backlight Inverter

蘇聖琪(Sheng-Chi Su)

指導教授 ： 陳秋麟

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.00678

摘要

背光源系統是液晶顯示器中非常重要的一部分，其消耗的能源佔了整個系統的大部分，因此將壓電變壓器利用在背光源系統中將可追求更好的能源效率使用。
壓電變壓器是高效率的電能轉換元件，與傳統電磁式變壓器相比，它具有更低的電磁波干擾、更高的安全性以及薄型化的優點。但是壓電變壓器需要操作在共振頻率才會達到最高的升壓比與效率，所以如何將壓電變壓器維持操作在工作頻率是一個重要因素。
本論文針對壓電變壓器在背光源系統中的應用進行探討，主要針對壓電變壓器輸入電流與輸入電壓相位差與頻率和增益的關係提出一種控制方式，並利用壓電變壓器輸入電流與電壓的相位差作為回授控制的訊號以達成壓電變壓器工作頻率的維持，另外利用脈衝忽略與強迫連續操作模式來調節冷陰極管亮度，並且設計實驗點亮冷陰極管並測量其效率。

關鍵字

壓電變壓器 ； 被光反流器

並列摘要

The backlight system is one of the most important parts in the liquid crystal display (LCD). It consumes most of the power of the whole system. To achieve higher power efficiency, piezoelectric transformers are utilized in the backlight systems.
A piezoelectric transformer can be a high-efficiency power converter. Compared with a traditional electromagnetic transformer, it has many advantages such as lower electromagnetic interference (EMI), higher safety, and smaller volume. However, a piezoelectric transformer has the highest efficiency and the highest voltage gain only when it is operated around its resonant frequency. As a result, it is very important to maintain the operating frequency of a piezoelectric transformer.
This thesis is focused on the application of the piezoelectric transformer in the backlight system. The relations between the phase difference of the input voltage and the output current, operating frequency, and voltage gain are discussed. A phase control strategy is also proposed. The control strategy uses the phase comparing with the input voltage signal and the input current signal to maintain the operating frequency of the piezoelectric transformer. We use the burst mode to regulate the brightness of the CCFL. We also ignite the CCFL and measure the efficiency in the experiment. The backlight system is one of the most important parts in the liquid crystal display (LCD). It consumes most of the power of the whole system. To achieve higher power efficiency, piezoelectric transformers are utilized in the backlight systems.
A piezoelectric transformer can be a high-efficiency power converter. Compared with a traditional electromagnetic transformer, it has many advantages such as lower electromagnetic interference (EMI), higher safety, and smaller volume. However, a piezoelectric transformer has the highest efficiency and the highest voltage gain only when it is operated around its resonant frequency. As a result, it is very important to maintain the operating frequency of a piezoelectric transformer.
This thesis is focused on the application of the piezoelectric transformer in the backlight system. The relations between the phase difference of the input voltage and the output current, operating frequency, and voltage gain are discussed. A phase control strategy is also proposed. The control strategy uses the phase comparing with the input voltage signal and the input current signal to maintain the operating frequency of the piezoelectric transformer. We use the burst mode to regulate the brightness of the CCFL. We also ignite the CCFL and measure the efficiency in the experiment.

並列關鍵字

Piezoelectric ； Backlight

參考文獻

[3] 林柏丞 ”相位控制之壓電背光反流器”，中華民國九十四年六月 國立台灣大學 電子工程學研究所碩士論文

[6] E. Dallago and A.Danioni, “Resonance frequency tracking control for piezoelectric transformer DC-DC converter,” Electronics Letters, Vol.37, No.22, pp.1317-1318, Oct. 2001.

[7] 黃朝巖 ”壓電式背光反流器系統控制晶片”，中華民國九十三年六月 國立台灣大學電子工程學研究所碩士論文

[1] H. Satoh, Y. Ino and H. Shiotani, “Inverter circuit for lighting for cold cathode tube by the use of the piezoelectric transformer,” Patent US5854543, Dec. 1998.

[2] O. Kawasaki and T. Gun, “Inverter power source apparatus using a piezoelectric transformer,” Patent US5796213, Aug. 1998.