Design considerations for a CCFL and its surroundings

Abstract

Abstract— A TFT‐LCD module includes a backlight unit, which normally uses one or more thin cold‐cathode fluorescent lamps (CCFLs). Since a CCFL is driven at high frequency and high voltage, there is a leakage current. In recent years, TFT‐LCD modules have been getting thinner, with a wider screen size and a narrower frame; consequently, the leakage current has come to have a significant influence on the design of the LCD module and the dc/ac inverter unit that generates the high‐voltage ac to drive the CCFL. It is actually impossible to probe the inside of a working CCFL because of the high voltage, high frequency, and low electric discharge current. This fact adds to the difficulty of the analysis and the design. This paper proposes an electrical model of a CCFL and a simulation method using the model, making it possible to analyze the inside of the CCFL and to provide some important parameters that are required for the basic design of the LCD module and the dc/ac inverter, before the construction and measurement of actual samples.