Backlight driver of liquid crystal display device and method for driving the same to maintain stability of the duty ratio of the PWM signal driving the backlight

摘要

A backlight driver and a method of driving the same are disclosed, which remove an unstable duty ratio by filtering an input PWM signal so as to prevent backlight flicker although the input PWM signal becomes unstable. The backlight driver includes a duty ratio detector for detecting a duty ratio of an input pulse width modulation (PWM) signal; a duty ratio filter for detecting a difference between a current duty ratio received from the duty ratio detector and a previous duty ratio, determining whether the detected duty ratio difference satisfies a preset reference condition, selecting one of the current duty ratio and the previous duty ratio, and outputting the selected duty ratio; and a PWM generator for generating an output PWM signal obtained when a selected duty ratio from the duty ratio filter is reflected in an input synchronization signal, and outputting the output PWM signal to a backlight unit.

主权项

1. A backlight driver comprising:
a duty ratio detector for detecting a duty ratio of an input pulse width modulation (PWM) signal; a buffer for delaying a current duty ratio from the duty ratio detector by one frame, and outputting the delayed duty ratio as a previous duty ratio; a duty ratio filter for detecting a difference between the current duty ratio received from the duty ratio detector and the previous duty ratio received from the buffer, the duty ratio filter comprising:
a duty ratio comparator for comparing the previous duty ratio with a current duty ratio to detect the duty ratio difference;a duty ratio determination circuit for comparing the duty ratio difference from the duty ratio comparator with a reference condition and outputting a flag signal indicating whether the reference condition is satisfied; andan output multiplexer for selecting one of the previous duty ratio from the duty ratio comparator and the current duty ratio in response to the flag signal from the duty ratio determination circuit and outputting the selected duty ratio; an input multiplexer for selecting one of the delayed duty ratio from the buffer and the selected duty ratio from the output multiplexer in response to a flag signal from the duty ratio determination signal, and outputting the selected duty ratio as the previous duty ratio for a next cycle of the input PWM signal; and a PWM generator for generating an output PWM signal obtained when a selected duty ratio from the duty ratio filter is reflected in an input synchronization signal, and outputting the output PWM signal to a backlight unit.