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

摘要

The invention discloses an LED backlight drive circuit, an LCD device and a driving method. The LED backlight drive circuit includes 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 the power source. The LED backlight drive circuit further includes a first comparator; a cathode of the first comparator is connected to a first reference voltage, an anode of the first comparator is coupled with the output terminal of the power source, and the output terminal of the first comparator is coupled with a control end of the first controllable switch; when the anode voltage of the first comparator exceeds the cathode voltage, the output terminal of the first comparator drives the first controllable switch to be conducted. In the invention, the LED lightbar only can be conducted at the predetermined voltage. Thus, the LED will be unable to be lighted even if the electric quantity is stored in the output capacitor; only when the output voltage achieves the predetermined voltage in the complete ON operation, the first controllable switch is able to be conducted, which solves the problem of LED blinking in the ON operation.

主权项

1. An LED backlight drive circuit, comprising: a power source; wherein 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, a 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.