Method for controlling LED-based backlight module

• US 20070262732A1
• Filed: 05/10/2006
• Published: 11/15/2007
• Est. Priority Date: 05/10/2006
• Status: Abandoned Application

• Current Assignee: VastView Technology Inc.
• Original Assignee: VastView Technology Inc.
• Inventors: Shen, Yuh-Ren
• Application Number:
  US11/430,937
• Publication Number:
  US 20070262732A1
• Time in Patent Office: Days
• US Class Current: 315/312
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/327 Burst dimming

Abstract

The method of the present invention turns off the line of LEDs of a backlight module behind the currently enabled scanline of a LCD device so that the transient behavior of the liquid crystal molecules are less obvious, thereby enhancing the dynamic response of the LCD device. For one type of embodiments, in accordance with the top-down scanning of the LCD device, the corresponding horizontal lines of the LEDs of the backlight module are turned off in a certain manner so that they exhibit a lighting (or, more precisely, darkening) pattern as if they are also “scanned” from top to down. For another type of embodiments, the horizontal lines of the LEDs of the backlight module are turned off and on simultaneously so that the backlight module actually “flashes” the LCD device.

Claims

1. A method for controlling a LED-based, direct-lit backlight module of a display device, said backlight module having a plurality of LEDs as light source arranged in a plurality of horizontal lines, said backlight module having a plurality of driver, each driving at least one of said lines of LEDs, said drivers being connected to a driver controller in an appropriate manner, said method, being implemented in said driver controller, comprising the steps of:

applying driver control signals having a train of pulses to said drivers respectively,

said driver control signals having a frequency being a multiple integral of the frame rate of said display device and a duty cycle at least 50%, the phase of said driver control signals being delayed sequentially line by line from top to bottom so that, within a frame time, said lines of LEDs being sequentially turned off from top to bottom at least once and, after the bottommost line of LEDs is turned off, the process repeats from the topmost line of LEDs.

2. The method according to claim 1, wherein said display device is one of a LCD device, a plasma display device, and an OLED display device.

3. The method according to claim 1, wherein said appropriate manner of connection is one of a series connection and a parallel connection.

4. The method according to claim 1, wherein said duty cycle is set appropriately so as to achieve a desired brightness of said backlight module.

5. The method according to claim 1, wherein, for each of said driver control signals, the pulse for turning on a line of LEDs for the first time in a frame time has a stepwise rising edge.

6. The method according to claim 1, wherein, for each of said driver control signals, the pulse before a line of LEDs is turned off for the first time in a frame time has a stepwise decreasing edge.

7. The method according to claim 1, wherein, for each of said driver control signals in a frame time, the pulse before a line of LEDs is turned off for the first time has a stepwise decreasing edge;

and the pulse for turning on said line of LEDs for the first time has a stepwise rising edge.

8. A method for controlling a LED-based, direct-lit backlight module of a display device, said backlight module having a plurality of LEDs as light source arranged in a plurality of horizontal lines, said backlight module having a plurality of driver, each driving at least one of said lines of LEDs, said drivers being connected to a driver controller in an appropriate manner, said method, being implemented in said driver controller, comprising the following steps:

applying a driver control signal having a train of pulses to said drivers simultaneously, said driver control signal having a frequency being a multiple integral of the frame rate of said display device and a duty cycle at least 50% so that, within a frame time, said lines of LEDs being turned on and off simultaneously and periodically.

9. The method according to claim 8, wherein said display device is one of a LCD device, a plasma display device, and an OLED display device.

10. The method according to claim 8, wherein said appropriate manner of connection is one of a series connection and a parallel connection.

11. The method according to claim 8, wherein said duty cycle is set appropriately so as to achieve a desired brightness of said backlight module.

12. A method for controlling a LED-based, direct-lit backlight module of a display device, said backlight module having a plurality of LEDs as light source arranged in a plurality of horizontal lines, said backlight module having a plurality of driver, each driving at least one of said lines of LEDs, said drivers being connected to a driver controller in an appropriate manner, said method, being implemented in said driver controller, comprising the following steps:

applying a driver control signal having a train of pulses to said drivers of odd-numbered lines of LEDs simultaneously, said driver control signal having a frequency being a multiple integral of the frame rate of said display device and a duty cycle at least 50%; and

concurrently applying another driver control signal which is the inversion of said driver control signal to said drivers of even-numbered lines of LEDs simultaneously.

13. The method according to claim 12, wherein said display device is one of a LCD device, a plasma display device, and an OLED display device.

14. The method according to claim 12, wherein said appropriate manner of connection is one of a series connection and a parallel connection.

15. The method according to claim 12, wherein, when a scanline of said display device is enabled, the pulse level of said driver control signal for a line of LEDs corresponding to said scanline is reduced to a lower level and then restored to the normal level in subsequent pulses.

16. The method according to claim 12, wherein, when a scanline of said display device is enabled, said driver control signal for a line of LEDs corresponding to said scanline stops to provide pulses.

17. The method according to claim 16, wherein, before said driver control signal for said corresponding line of LEDs stops to provide pulses, the preceding pulse is reduced to a lower level.

18. The method according to claim 16, wherein, when said driver control signal resumes providing pulses, the pulse level of said driver control signal for said corresponding line of LEDs is reduced to a lower level and then restored to the normal level in subsequent pulses.