Isolated boost circuit, backlight module and liquid crystal display device

Abstract

An isolating type boosted circuit, a backlight module and a liquid crystal display device thereof are disclosed. The isolating type boosted circuit provides a power source for light-emitting diode (LED) string lights (30) in the backlight module of the liquid crystal display device. The liquid crystal display device comprises a voltage input end, a driving signal unit (21), a transformer (T20), and a controllable reverse isolation circuit, wherein the transformer (T20) comprises a primary coil (L1) and a secondary coil (L2), the voltage input end is connected with a same-name end of the primary coil (L1), a different-name end of the secondary coil (L2) is connected with the LED string lights (30), the different-name end of the primary coil (L1) is connected with the end 01 of the controllable reverse isolation circuit, the same-name end of the secondary coil (L2) is connected to the end 02 of the controllable reverse isolation circuit, and the end 03 of the controllable reverse isolation circuit is connected with the driving signal unit (21). The isolating type boosted circuit can effectively improve efficiency of the whole circuit, safety performance of the circuit, and stability of the circuit.

Description

technical field [0001] The invention belongs to the field of liquid crystal display, and in particular relates to an isolated boost circuit, a backlight module adopting the isolated boost circuit and a liquid crystal display device. Background technique [0002] Existing LCD devices usually use LEDs as backlight sources. figure 1 It is a schematic diagram of an existing LED backlight boosting circuit. like figure 1 As shown, the opposite end of the primary coil of the transformer T900 is connected to the positive pole of the diode D1, and the same end of the secondary coil is connected to the negative pole of the diode. When the drive signal unit 901 sends a turn-on signal to the MOS transistor Q1, the MOS transistor Q1 is turned on, and the diode D1 prevents the high voltage at the same name end of the secondary coil of the transformer T900 from damaging the MOS transistor Q1; when the drive signal unit 901 sends a cut-off signal to the MOS transistor Q1 When the MOS tra...

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Problems solved by technology

[0003] But in the above circuit, on the one hand, when the MOS transistor Q1 is turned on, when the MOS is turned on, the diode D1 between the primary coil and the secondary coil of the transformer T900 reversely isolates the high voltage on the secondary coil, and the diode D1 still There is a reverse current, the diode D1 will consume power, the temperature will rise, and the reverse current will increase with the temperature of the diode D1, such a vicious circle will cause the power consumption on the diode D1 to increase, and the temperature will be too high , the overall circuit efficiency will decrease

On the other hand, the transformer T900 has a leakage inductance, and the energy stored in the leakage inductance when the MOS transistor Q1 is turned on will be released with a large peak voltage when the MOS transistor Q1 is turned off, which will have an impact on the diode D1 and the MOS transistor Q1 , accelerates its aging, and will break down in severe cases

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