DocumentCode :
1195532
Title :
A Low-Cost High-Efficiency CCFL Inverter With New Capacitive Sensing and Control
Author :
Kim, Sang Kyung ; Han, Hee Seok ; Woo, Young Jin ; Cho, Gyu Hyeong
Author_Institution :
Korea Adv. Inst. of Sci. & Technol., Daejeon
Volume :
21
Issue :
5
fYear :
2006
Firstpage :
1444
Lastpage :
1451
Abstract :
A new low-cost and efficient cold cathode fluorescent lamp (CCFL) inverter for liquid crystal display (LCD) application is suggested in this paper. The topology of the inverter is derived from modified class E-type resonant electronic ballasts and has a dc-like input current. In addition, a new sensing circuit for lamp current and transformer voltage is proposed. A simple RC-network measures the voltage of a ballasting capacitor in series with the lamp instead of the lamp current itself while the lamp is floated. Utilizing the printed circuit board capacitors for the sensing capacitors and integrating small-valued sensing resistors into a control integrated circuit make the inverter very simple, efficient, and cost-effective. The new sensing circuit can solve many problems that arise when a terminal of the lamp is grounded to sense the lamp current. The control circuits for the prototype experiments are also described in detail. The frequency control scheme with a fixed off-time and a varying on-time was chosen to maintain the operation of zero-voltage switching in the entire dimming range and to reduce the complexity of the control circuits. The control circuits have an analog dimming function using a current control loop, a low frequency pulsewidth modulation dimming, open-lamp protection and voltage regulation, and soft-on/off functions
Keywords :
RC circuits; capacitive sensors; electric current control; fluorescent lamps; frequency control; lamp accessories; lighting control; liquid crystal displays; resonant invertors; switching convertors; voltage control; voltage measurement; zero voltage switching; CCFL inverter; LCD; RC network; capacitive control; capacitive sensing; cold cathode fluorescent lamp inverter; control circuits; current control loop; dimming; frequency control; lamp current; liquid crystal display; modified class E-type resonant electronic ballasts; open-lamp protection; printed circuit board capacitors; sensing circuit; transformer voltage; voltage measurement; voltage regulation; zero-voltage switching; Capacitors; Cathodes; Circuit topology; Electronic ballasts; Fluorescent lamps; Inverters; Liquid crystal displays; Open loop systems; Resonance; Voltage control; Class E; cold-cathode fluorescent lamp (CCFL); current sensing; electronic ballasts; printed circuit board (PCB) capacitance; protection; resonant inverter; voltage sensing;
fLanguage :
English
Journal_Title :
Power Electronics, IEEE Transactions on
Publisher :
ieee
ISSN :
0885-8993
Type :
jour
DOI :
10.1109/TPEL.2006.880256
Filename :
1687995
Link To Document :
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