Backlight driving circuit, backlight module and liquid crystal display device

Abstract

The invention discloses a backlight driving circuit, a backlight module and a liquid crystal display device; the backlight driving circuit comprises a power supply module, an inductor connected with the output end of the power supply module, and an LED (light-emitting diode) light bar connected with the inductor in series, wherein a monitoring module is used for detecting output current of the inductor and is coupled between the inductor and the LED light bar, a controllable switch is connected between the output end of the inductor and the grounded end of the backlight driving circuit, and the monitoring module is coupled with the controllable switch; and when the output current value of the inductor is lower than a predetermined value, the monitoring module controls the controllable switch to conduct. According to the invention, the inductor can work in a current continuous mode, and thus relatively high peak current is avoided from generating, the device is protected and the circuit is safe. In addition, the peak current value of the inductor is reduced, and thus an element with relatively low specification can be used, so as to reduce the manufacture cost.

Description

technical field [0001] The invention relates to the field of liquid crystal display, and more specifically relates to a backlight driving circuit, a backlight module and a liquid crystal display device. Background technique [0002] A liquid crystal display device includes a liquid crystal panel and a backlight module for providing a light source for the liquid crystal panel. As the cost of LEDs decreases, most existing backlight modules use LEDs as light sources. see figure 1 The backlight module using LED as the light source usually connects multiple LEDs in series to form a light bar, and then uses a boost circuit to drive the light. The inductance L1 of the boost circuit is a very important component. When the LED load is constant, the inductance The size of will determine whether it works in current continuous or current discontinuous mode. When the inductance used is less than the inductance in the critical working mode due to process deviation, the inductor will wor...

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Problems solved by technology

When the inductance used is less than the inductance in the critical working mode due to process deviation, the inductor will work in the current discontinuous mode. Although the effective value of the inductor current is the same, the inductor peak current in the current discontinuous mode is higher than that in the current continuous mode. under the big (such as figure 2 ), so that some key components such as MOS transistor Q1 and diode D1 in the circuit need greater bearing capacity. If the situation is serious, the key components will be damaged

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