Drive method for backlight module of LCD device and its circuit

Abstract

The invention comprises: after a plurality of luminous tubes are connected in parallel, and then connecting two nodes in parallel to the two ends at secondary side of the voltage increase center tap transformer; the center tap at the secondary side is connected to the ground end; the primary side of the voltage increase transformer is connected to a high frequency signal and is driven by the high frequency signal; thereby, both ends of the luminous tubes will get high voltage and identical current making the luminous tubes generate even light.

Description

technical field [0001] The invention relates to a driving method and a circuit of a backlight module of a liquid crystal display, in particular to a driving method and a circuit for driving the backlight module to produce uniform luminance. Background technique [0002] The liquid crystal display panel itself does not have self-luminous characteristics, so it needs to be equipped with a backlight module to provide a display light source. Among them, a large-sized liquid crystal display panel requires a uniform and high-brightness backlight module, so most of them use cold cathode lamps as the light source. [0003] At present, there are not a few manufacturers at home and abroad that develop driving circuits for cold cathode lamps, and the functional requirements of the driving circuits designed by each manufacturer are different. As the size of the liquid crystal display panel increases, the number of lamp tubes also increases, so that the early lamp drive circuits are no l...

AI Technical Summary

Problems solved by technology

[0006] 1. Low power conversion efficiency: the conversion efficiency of the entire drive circuit is only about 70% because the AC power is first converted into a low-voltage DC power source by the switching power supply unit, and then converted into a high-voltage and high-frequency AC power source by a transformer.

[0007] 2. Easy to generate high heat: Since the power supply is not completely and effectively converted, about 30% of the energy of the power supply will be converted into heat energy, making the backlight module prone to heat

If this backlight module is applied to the liquid crystal display panel, the heat generated will accelerate the deterioration of the liquid crystal, shorten the service life of the liquid crystal display panel, relatively increase the failure rate of the entire liquid crystal display, and reduce the reliability of the product

[0008] 3. Uneven brightness: such as Figure 8 and Figure 9 As shown, since the cold cathode lamp tube 71 is connected to both ends of the secondary side of the step-up transformer 70, one end of the secondary side is connected to the high voltage, and the other end is connected to the ground terminal, so a high-voltage high-frequency power input lamp tube At 71 o'clock, the lamp tube 71 is driven to light up

[0010] 4. Applied to driving multiple lamp tubes, there are disadvantages such as complex circuits, more components, and higher costs: limited by the connection relationship between the lamp tube 71 and the step-up transformer 70, such as Figure 10 As shown, if the front driving circuit is to be connected with a plurality of lamp tubes 71, then a plurality of step-up transformers 70 need to be connected in parallel.

[0011] From the previous explanations, it can be seen that there are still quite a few shortcomings to be overcome in the application of the current lamp drive circuit to drive multiple lamps.

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