| 摘要 |
PURPOSE: A TV system for automatically performing PLL(phase locked loop) locking according to an input signal is to increase a speed of a horizontal PLL when a video signal is input to lock phase, thereby preventing jitter of an image and color error. CONSTITUTION: An input portion(10) receives an RF(radio frequency) signal and a video signal from an outside and then outputs CVBS(composite video, burst, sync) signal. A signal determining portion(20) determines whether the CVBS signal is the RF signal or the video signal and then outputs a result. A micro-computer(30) outputs the first control signal to operate the horizontal PLL at a normal speed if the CVBS signal is the RF signal, and outputs the second signal to operate the horizontal PLL at a higher speed then the normal speed if the CVBS signal is the video signal. A video processor(40) operates the horizontal PLL at the normal speed when the first control signal is input, and operates the horizontal PLL at the higher speed when the second control signal is input to output the CVSB signal. A digital/analog converter(50) converts the CVBS signal into a luminance signal and two color difference signals. And a display portion(60) processes the signal output from the video processor.
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