| 摘要 |
PROBLEM TO BE SOLVED: To process both an SD signal and an HD signal by a picture switching device, and to automatically operate switching according to an inputted signal. SOLUTION: When an input picture signal is an SD signal, a 270 MHz reproduction clock is inputted from a DC reproducing part 17 through an input equalizer 16 to first and second PLL circuits 20a and 20b. The first PLL circuit 20a is locked to the input frequencies of the SD signal, and detected by a lock detecting means 21. The reproduction clock of the first PLL circuit 20a is selected by a PLL circuit selecting means 22 according to the detected result, and inputted to a latch circuit 18, and outputted through an output driver 19 by removing the jitter of the picture signal. When the input picture signal is the SD signal, the second PLL circuit 20b is not locked, and the reproduction clock of the second PLL circuit 20b is not selected. Thus, the corresponding reproduction clock can be outputted by detecting inputted HD signal and SD signal.
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