Research On The Driver For External Electrode Fluorescent Lamps(EEFL)

As one of Cold Cathode Fluorescent Lamp (CCFL),the External Electrode Fluorescent Lamps(EEFL), presents good performances such as mercury-free environment, high lightness, longevity of service, low power consumption, instantaneous startup and so on. There will be a huge market. So EEFL will play the more and more important position in the future daily illumination field.This paper first introduces the development backgrand and electrical characteristic about EEFL.This study analyzes Royer topology frames and half-bridge topology based on the theory of the modern inverter,and gives some parameters. At last,two kind of experimental goods are finished. So under the different input voltage,the paper aims to work out the driver device.When DC 16～24V is given, this paper analyses the Royer and gives the equivalent of the working model. It also studys the conditions of the quasi-sine work. By using discrete components, parallel resonant inverter is designed, which has the BUCK circuit based on TL494. According to the design,it selected some components and developed a prototype.The experiment proved the feasibility and reliability of the design.When AC 220V is given, two issues are considered. It is very important to reduce the current harmonic and improve the power factor for power supply.The paper introuduced the principles and characteristics of the passive power factor correction (PPFC) and active power factor correction circuit (APFC),and presents the design method for streaming PPFC circuit, the charge pump power factor correction circuit(CPPFC) and APFC circuit based on L6561.By comparing the experimental results,it achieved the expected goal. This paper also examines the equivalent EEFL model drived by the half-bridge inverter circuit, and analyses the conditions of soft-switch technology using sinusoidal driving method. It introduces the performance,characteristics and work patterns of IR21571s chip. The driver based on IR21571s is designed for five EEFL and a prototype is developed. The results show that the EEFL driver which meet the the requirements of harmonic and power factor operates well and reachs the goal.