| 摘要 |
PURPOSE:To remove malfunction by driving a monostable multivibrator by an ID signal initially generated from an ID generating circuit, inverting the output signal of the multivibrator and impressing the output signal to a phase shifting circuit. CONSTITUTION:The ID signal generating circuit 17 compares the phase of a color burst signal extracted by a burst extracting circuit 16 with that of an output signal of an oscillation circuit 10 shifted by 90 deg. through a 90 deg. shifting circuit 21. When colors are synchronized, the output signal of the circuit 17 is kept at the high level. When the colors are asynchronized and the phase difference between both the signals can no be kept at 90 deg., the output of the circuit 17 is turned to 'L' and the 'L' output is applied to the monostable multivibrator 18 as an ID signal. Consequently, the output signal of the multivibrator 18 is inverted and the phase shifting circuit 14 is forcedly driven. When a forced driving signal is impressed from the multivibrator 18, the phase of the output signal of the circuit 14 is turned to 180 deg. in case of the NTSC system and 90 deg. in case of the PAL system.
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