Backlight driving board and LCD device

1. A backlight driving board for driving a backlight source, comprising:

a microprocessor for receiving a display mode switching signal and a synchronization signal from a liquid crystal driving board, and generating a first pulse width modulation signal corresponding to the backlight source according to the display mode switching signal and the synchronization signal, and the backlight driving board and the liquid crystal driving board are connected to a common ground; and

a constant current driver chip for controlling a duty ratio of a current flowing through the backlight source according to the first pulse width modulation signal;

wherein, the display mode switching signal is a 2D/3D switching signal;

wherein, the constant current driver chip further receives the display mode switching signal and controls a magnitude of the current flowing through the backlight source, wherein the constant current driver chip and the display mode switching signal are connected; and wherein, the constant current driver chip comprises a comparator and a first controlled switch corresponding to the backlight source, wherein, the first controlled switch is connected in series with the backlight source, a positive input terminal of the comparator is connected to the display mode switching signal, and a negative input terminal of the comparator is directly connected to a first terminal of the first controlled switch and is grounded through a resistor, an output terminal of the comparator is directly connected to a control terminal of the first controlled switch, a second terminal of the first controlled switch is directly connected to a second end of the backlight source, and the control terminal of the first controlled switch is connected to the first pulse width modulation signal, the display mode switching signal generates different voltage values in different display modes at the positive input terminal of the comparator to control the magnitude of the current flowing through the backlight source.

2. The backlight driving board according to claim 1 , wherein, the backlight driving board further comprises a power supply module connected at a first end of the backlight source for providing power to the backlight source, and in a 3D display mode, a duty ratio of a current of the backlight source is fixed, and in a 2D display mode, a duty ratio of a current of the backlight source is arbitrarily adjusted.

3. A backlight driving board for driving a backlight source, comprising:

a microprocessor for receiving a display mode switching signal and a synchronization signal from a liquid crystal driving board, and generating a first pulse width modulation signal corresponding to the backlight source according to the display mode switching signal and the synchronization signal; and

a constant current driver chip for controlling an operation state of the backlight source according to the first pulse width modulation signal, wherein, the constant current driver chip receives the display mode switching signal and controls a duty ration of a current flowing through the backlight source according to the first pulse width modulation signal;

wherein, the display mode switching signal is a 2D/3D switching signal;

wherein, the constant current driver chip further receives the display mode switching signal and controls a magnitude of the current flowing through the backlight source, wherein the constant current driver chip and the display mode switching signal are connected; and

wherein, the constant current driver chip comprises a comparator and a first controlled switch corresponding to the backlight source, wherein the first controlled switch is connected in series with the backlight source, a positive input terminal of the comparator is connected to the display mode switching signal, and a negative input terminal of the comparator is connected to a first terminal of the first controlled switch and is grounded through a resistor, an output terminal of the comparator is connected to a control terminal of the first controlled switch, a second terminal of the first controlled switch is connected to a second end of the backlight source, and the control terminal of the first controlled switch is connected to the first pulse width modulation signal, the display mode switching signal generates different voltage values in different display modes at the positive input terminal of the comparator to control the magnitude of the current flowing through the backlight source.

4. The backlight driving board according to claim 3 , wherein, the backlight driving board further comprises a power supply module connected at a first end of the backlight source for providing power to the backlight source, and in a 3D display mode, a duty ratio of a current of the backlight source is fixed, and in a 2D display mode, a duty ratio of a current of the backlight source is arbitrarily adjusted.

5. The backlight driving board according to claim 4 , wherein, the power supply module includes an inductor, a second controlled switch, a rectifier diode and a capacitor, a first end of the inductor connecting to a power source voltage, a first terminal of the second controlled switch connecting to a second end of the inductor, a second terminal of the second controlled switch connecting to a ground, an anode electrode of the rectifier diode connecting to the second end of the inductor, a cathode electrode of the rectifier diode connecting to a first end of the backlight source, an end of the capacitor connecting to a location between the rectifier diode and the backlight source, the other end of the capacitor connecting to the ground, and a control terminal of the second controlled switch connects to a second pulse width modulation signal.

6. The backlight driving board according to claim 4 , wherein, the backlight source is an LED string, and a positive electrode of the LED string connects to the power supply module, and a negative electrode of the LED string connects to the second terminal of the second controlled switch.

7. The backlight driving board according to claim 3 , wherein, the backlight driving board and the liquid crystal driving board are formed with a common ground connection.

8. An LCD device comprising a liquid crystal driving board, a backlight source, and a backlight driving board, wherein, the backlight driving board comprises:

a microprocessor for receiving a display mode switching signal and a synchronization signal from a liquid crystal driving board, and generating a first pulse width modulation signal corresponding to the backlight source according to the display mode switching signal and the synchronization signal; and

a constant current driver chip for controlling an operation state of the backlight source according to the first pulse width modulation signal, wherein, the constant current driver chip receives the display mode switching signal and controls a duty ration of a current flowing through the backlight source according to the first pulse width modulation signal;

wherein, the display mode switching signal is a 2D/3D switching signal;

wherein, the constant current driver chip further receives the display mode switching signal and controls a magnitude of the current flowing through the backlight source, wherein the constant current driver chip and the display mode switching signal are connected; and

wherein, the constant current driver chip comprises a comparator and a first controlled switch corresponding to the backlight source, wherein the first controlled switch is connected in series with the backlight source, a positive input terminal of the comparator is connected to the display mode switching signal, and a negative input terminal of the comparator is connected to a first terminal of the first controlled switch and is grounded through a resistor, an output terminal of the comparator is connected to a control terminal of the first controlled switch, a second terminal of the first controlled switch is connected to a second end of the backlight source, and the control terminal of the first controlled switch is connected to the first pulse width modulation signal, the display mode switching signal generates different voltage values in different display modes at the positive input terminal of the comparator to control the magnitude of the current flowing through the backlight source.

9. The LCD device according to claim 8 , wherein, the backlight driving board further comprises a power supply module connected at a first end of the backlight source for providing power to the backlight source, and in a 3D display mode, a duty ratio of a current of the backlight source is fixed, and in a 2D display mode, a duty ratio of a current of the backlight source can be arbitrarily adjusted.

10. The LCD device according to claim 9 , wherein, the power supply module includes an inductor, a second controlled switch, a rectifier diode and a capacitor, a first end of the inductor connecting to a power source voltage, a first terminal of the second controlled switch connecting to a second end of the inductor, a second terminal of the second controlled switch connecting to a ground, an anode electrode of the rectifier diode connecting to the second end of the inductor, a cathode electrode of the rectifier diode connecting to a first end of the backlight source, an end of the capacitor connecting to a location between the rectifier diode and the backlight source, the other end of the capacitor connecting to the ground, and a control terminal of the second controlled switch connects to a second pulse width modulation signal.

11. The LCD device according to claim 9 , wherein, the backlight source is an LED string, and a positive electrode of the LED string connects to the power supply module, and a negative electrode of the LED string connects to the second terminal of the second controlled switch.