| 摘要 |
PROBLEM TO BE SOLVED: To provide a vertical synchronization stabilizing apparatus for performing synchronization operations by using a vertical synchronization signal capable of providing a stable vertical synchronization signal even when the apparatus receives an input signal of a standard system, or a non-standard system or in a strong electric field or in a weak electric field. SOLUTION: A microcomputer 8 allows a synchronization signal changeover switch 10 to be thrown to a position of receiving an external vertical synchronization signal 9 when the apparatus receives an input signal of the standard system in the strong electric field state. When an electric field level detected by the electric field level detection circuit 7 is close to a level of a weak electric field, the microcomputer 8 allows the synchronization signal changeover switch 10 to be thrown to a position connected to an automatic controller 11, also periodically selects the position of the external vertical synchronization signal 9 from the position of the automatic controller 11 at a prescribed interval as its control, and fixes the automatic control when the electric field strength reaches a weak electric field strength. The apparatus conducts similar control for a non-standard input signal. COPYRIGHT: (C)2004,JPO
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