- 學位論文
使用壓電變壓器於多支冷陰極管安定器的設計
Design of Electronic Ballast with Piezoelectric Transformer for Multiple Cold Cathode Fluorescent Lamps
摘要
摘 要 本論文提出一組半橋升壓式換流器架構來驅動冷陰極管，其整體架構主要是由半橋升壓式換流器再加上壓電變壓器所組成，利用壓電變壓器內部高升壓比的特性來提供冷陰極管啟動前的高輸出電壓與啟動後穩定的正常工作電壓與電流。 壓電變壓器比傳統電磁式變壓器在使用上具有許多優點，如它無電磁干擾、有高效率與低發熱量等優點，再加上壓電變壓器能完全的供應冷陰極管所需的高啟動電壓，所以很適合用來驅動冷陰極管，但是，因為壓電變壓器有許多種形式，也就是說可能會因為升壓比或是額定功率不同，使得在驅動多根冷陰極管時會有燈管亮度不一致，甚至會有無法完全點亮冷陰極管的缺點。所以提出以高頻升壓變壓器結合低升壓比高功率輸出的壓電變壓器，經由適當的電路設計使得單一壓電變壓器可以成功的驅動多支冷陰極管。 最後，針對本論文所提出的驅動電路分別應用於不同長度的冷陰極管，再藉由電容均流的技術來達到燈管亮度一致的效果，以符合不同尺寸的背光模組，並以實驗來證明所提出之架構的可行性。
並列摘要
Abstract This thesis presents a study of using a half-bridge step up structure to drive Cold Cathode Fluorescent Lamp (CCFL). The system is assembled as a set of inverter with a Piezoelectric Transformer (PT). By means of the high step-up property of PT, it supplies the high voltage output required for starting up CCFL and also provides the stable working voltage and current after that. PT has several advantages over the conventional transformers, for instance, it does not induce EMI, it works with high efficiency, and it also results in low heat generation. PT is capable of supply sufficiently high voltage to driving CCFL, and therefore it is adequate for driving CCFL. However, owing to PT has several types with different step-up ratios or rated powers, it could cause uneven brightness of the lamps and even fail to drive when multiple CCFLs are operated. Therefore, this paper proposed a high frequency transformer series with a PT which has low step-up ratio and high power. By suitable circuit design, the system drives multiple CCFLs successfully. Finally, the balance capacitors are adapted to obtain even brightness of the lamps for different types of CCFLs. The experimental results verify the feasibility of the proposed circuit.