Driving circuit having voltage detecting circuit and liquid crystal display using same

A driving circuit for a liquid crystal display (LCD), comprising:

• a data driving integrated circuit (IC) for providing a plurality of gradation voltages to an LCD panel of the LCD;
• and
• a gate driving IC for scanning the LCD panel, the gate driving IC comprising a voltage detecting circuit for detecting an operation voltage applied thereon;
• wherein the voltage detecting circuit comprises an input terminal for receiving the operation voltage, an output terminal for providing an all-scanning signal, a first comparator, a second comparator, a first transistor, a second transistor, a first constant current power circuit, a second constant current power circuit, a constant voltage diode, a first resistor, and a second resistor, the first and second resistors are connected in series between the input terminal and ground, the first constant current circuit and the constant voltage diode are connected in series between the input terminal and ground, a joint node between the first and second resistors is connected to an inverting input of the first comparator, a joint node between the first constant current circuit and the constant voltage diode provides a constant reference voltage to a noninverting input of the first comparator, an output of the first comparator is connected to a base electrode of the first transistor, an emitter electrode of the first transistor is connected to ground, a collector electrode of the first transistor is connected to the input terminal via the second constant current power circuit, the collector electrode of the first transistor is connected to an inverting input of the second comparator, a noninverting input of the second comparator is connected to the output terminal, an output of the second comparator is connected to a base electrode of the second transistor, an emitter electrode of the second transistor is connected to ground, a collector electrode of the second transistor is connected to the output terminal, and the gate driving IC performs a function of turning on all of thin film transistors (TFTs) of the LCD panel when the operation voltage is lower than a predetermined threshold voltage.

A liquid crystal display (LCD) device, comprising:

• an LCD panel;
• a gate driving integrated circuit (IC) configured for scanning the LCD panel;
• a data driving IC configured for providing a plurality of gradation voltages to the LCD panel, the data driving IC comprising a voltage detecting circuit which detects an operation voltage applied thereon and is configured to provide an all-scanning signal to the gate driving IC;
• a primary control circuit board for providing the operation voltage to the data driving IC;
• and
• a flexible printed circuit board connected between the LCD panel and the primary control circuit board;
• wherein the voltage detecting circuit comprises an input terminal for receiving the operation voltage, an output terminal for providing the all-scanning signal, a first comparator, a second comparator, a first transistor, a second transistor, a first constant current power circuit, a second constant current power circuit, a constant voltage diode, a first resistor, and a second resistor, the first and second resistors are connected in series between the input terminal and ground, the first constant current circuit and the constant voltage diode are connected in series between the input terminal and ground, a joint node between the first and second resistors is connected to an inverting input of the first comparator, a joint node between the first constant current circuit and the constant voltage diode provides a constant reference voltage to a noninverting input of the first comparator, an output of the first comparator is connected to a base electrode of the first transistor, an emitter electrode of the first transistor is connected to ground, a collector electrode of the first transistor is connected to the input terminal via the second constant current power circuit, the collector electrode of the first transistor is connected to an inverting input of the second comparator, a noninverting input of the second comparator is connected to the output terminal, an output of the second comparator is connected to a base electrode of the second transistor, an emitter electrode of the second transistor is connected to ground, and a collector electrode of the second transistor is connected to the output terminal.