| 摘要 |
PURPOSE: An apparatus and a method for controlling a horizontal phase locked loop speed of a video display device are provided to sense a noise signal level and control the horizontal phase locked loop speed according to the sensed noise signal level, thereby preventing jitter and video distortion. CONSTITUTION: A comparator(100) receives synchronizing and clock signals of a video signal for generating a phase error. A video signal calculating part(130) receives the video signal for calculating a video signal energy level by horizontal lines of the video signal. A noise signal calculating part(140) calculates a signal energy level of a blanking section of the video signal. A control part(150) compares the signal energy levels of the video signal and the blanking section signal for outputting an HPLL(Horizontal Phase Locked Loop) speed control signal according to the comparison result. A filter(110) receives the phase error and the HPLL speed control signal for outputting an error value through a predetermined operation. An adder(120) adds a preliminarily set basic frequency to the output error value for outputting a final frequency.
|
