Multiple lamp tube driving system and flow equalizing circuit thereof

Abstract

The invention provides a multiple-lamp drive system, comprising a driving circuit; a main transformer, which is electrically connected with the driving circuit; a feedback circuit, which is electrically connected with the driving circuit; a lamp group, which is electrically connected with the feedback circuit and comprises at least two parallel connected lamps; and a current-sharing circuit, which is connected between a plurality of lamps and the main transformer and comprises at least a capacitor and a balance transformer. The balance transformer is bridge connected with a first lamp and a second lamp of the lamps while the capacitor is parallel connected with the balance transformer.

Description

technical field [0001] The present invention relates to a lamp tube driving system, in particular to a multi-lamp tube driving system and a current equalizing circuit thereof. Background technique [0002] In recent years, the application of flat panel displays has become more and more popular, among which liquid crystal displays (Liquid Crystal Display, LCD) are the mainstream in the market. With the technological development of liquid crystal displays, in order to meet the demand for large-scale practical use, the number of Cold Cathode Fluorescent Lamps (CCFL) used as backlights must be increased to provide sufficient brightness. For example, if the liquid crystal display increases to 40 inches, the number of lamp tubes it needs may increase to more than 30, but in this way, the brightness between the lamp tubes is prone to unevenness. There are two ways to solve this problem. [0003] Such as Figure 1A As shown, a known CCFL driving system 1 includes a driving circuit...

AI Technical Summary

Problems solved by technology

[0006] In order to make the luminance of the above-mentioned plurality of cold cathode fluorescent lamps 14 equal, the known technology realizes current sharing through the impedance matching relationship of the impedance matching network 15, wherein the impedance matching network is composed of two high-voltage capacitors C and a The two high-voltage capacitors C are respectively connected in series with the plurality of cold cathode fluorescent lamps 14 (as shown in the figure, they are implemented as two cold cathode fluorescent lamps), and the inductor L is electrically connected to the two cold cathode fluorescent lamps. Between the high-voltage capacitor C; although the drive system 1′ can achieve current sharing through impedance matching, this method is sensitive to switching frequency and load changes, and at the same time, too many design parameters need to be considered, resulting in complex design, especially for multi- When using a lamp system, its current equalization effect is not obvious

Images