Backlight Driving Board and LCD Device

• US 20140333859A1
• Filed: 03/27/2013
• Published: 11/13/2014
• Est. Priority Date: 03/20/2013
• Status: Active Grant

• Current Assignee: Shenzhen China Star Optoelectronics Technology Co., Ltd. (TCL Technology Group Corp.)
• Original Assignee: Shenzhen China Star Optoelectronics Technology Co., Ltd. (TCL Technology Group Corp.)
• Inventors: Zhang, Hua, Zhang, Xianming, Yang, Xiang
• Granted Patent: US 9,207,458 B2
• Time in Patent Office: Days
• US Class Current: 349/15
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines

Abstract

The present invention discloses a backlight driving board for driving a backlight source, comprising a microprocessor and a constant current driver chip. The microprocessor receives 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. The constant current driver chip controls an operation state of the backlight source according to the first pulse width modulation signal. The present invention can reduce the signal lines between the backlight driving board and the liquid crystal driving board in order to avoid the backlight driving board from external interference because of too many signal lines, and thus be able to enhance the stability of the LCD device when operatin

Claims

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.

2. The backlight driving board according to claim 1, 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.

3. The backlight driving board according to claim 2, wherein, the constant current driver chip comprises a comparator and a first controlled switch corresponding to 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.

5. 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.

6. The backlight driving board according to claim 5, wherein, the constant current driver chip further receives the display mode switching signal and controls a duty ratio of a current flowing through the backlight source according to the first pulse width modulation signal.

7. The backlight driving board according to claim 6, 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.

8. The backlight driving board according to claim 7, wherein, the constant current driver chip comprises a comparator and a first controlled switch respectively corresponding to 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 backlight driving board 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.

10. The backlight driving board 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 backlight driving board 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.

12. The backlight driving board according to claim 5, wherein, the backlight driving board and the liquid crystal driving board are formed with a common ground connection.

13. The backlight driving hoard according to claim 5, wherein, the display mode switching signal is a 2D)/3D switching signal.

14. An LCD device comprising a liquid crystal driving board, a backlight source, and a backlight driving board, wherein, the backlight driving hoard 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.

15. The LCD device according to claim 14, wherein, the constant current driver chip further receives the display mode switching signal and controls a duty ratio of a current flowing through the backlight source according to the first pulse width modulation signal.

16. The LCD device according to claim 15, 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.

17. The LCD device according to claim 16, wherein, the constant current driver chip comprises a comparator and a first controlled switch respectively corresponding to 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.

18. The LCD device according to claim 17, 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.

19. The LCD device according to claim 18, 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.

20. The LCD device according to claim 18, 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.