A novel design of U-Shaped CCFL in T8 tube to replace traditional fluorescent lamp

In this paper, one 13 W, 110 cm U-Shaped cold cathode fluorescent lamp (CCFL) is installed into a traditional T8 transparent tube with 60 cm in length. For retaining the original lighting capability of 18 W fluorescent lamp, a well-performed reflection plate was installed at the center to project the emitting light of CCFL in the same direction to promote the lighting efficiency. The zero-voltage switching technique is employed to implement the double-voltage-fed CCFL drive circuit of Class-D isolated resonant inverter to improve the conversion efficiency. By utilizing burst mode dimming technique to regulate light output, the CCFL output voltage was intermittently outputted and the required dimming functions can be achieved. This research fully utilized the inductance of traditional magnetic ballast to accomplish power factor corrector by including appropriate capacitor. Accordingly, the input characteristics can be improved and high power factor performance can be achieved as well.