LED backlight drive circuit, liquid crystal display device and driving method

An LCD device, comprising:

• an LED backlight drive circuit;
• said LED backlight drive circuit comprises a power source;
• an output capacitor and an LED lightbar which is connected in series with a first controllable switch are in parallel connection, and then are arranged between the output terminal and the ground terminal of said power source;
• said LED backlight drive circuit further comprises a first comparator;
• a cathode of said first comparator is directly connected to a first reference voltage, an anode of said first comparator is coupled with the output terminal of said power source, and the output terminal of said first comparator is coupled with a control end of said first controllable switch;
• when the anode voltage of said first comparator exceeds the cathode voltage, the output terminal of said first comparator drives said first controllable switch to be conducted, wherein said LED backlight drive circuit further comprises a second comparator;
• the anode of said second comparator is connected to a second reference voltage different from the first reference voltage, the cathode of said second comparator is coupled with the output terminal of said power source, and the output terminal of said second comparator is coupled with the control end of said first controllable switch;
• said second reference voltage is higher than said first reference voltage, when the cathode voltage of said first comparator exceeds the anode voltage, the output terminal of said first comparator drives said first controllable switch to be blocked.