| 摘要 |
PROBLEM TO BE SOLVED: To perform high precision nonstandard signal decision by a simple circuit composition even if using an operation clock which has an arbitrary frequency when deciding whether a horizontal frequency of an input image signal is one of nonstandards or not. SOLUTION: High precision measurement of the horizontal frequency is realized by a counter 31, a 1H holding circuit 32, and an excess calculation circuit 33 using lower bits S24 which represent high precision phase error information corresponding to a time shorter than a repeating period of an operation clock SCK out of phase error data S22 in an automatic frequency control (AFC) circuit 20 of a PLL composition based on a horizontal synchronous signal S1 separated by a synchronous separation circuit 10, and furthermore, the horizontal frequency measuring result S9 and a standard horizontal frequency data S11 established in a register 41 by a processor 60, are compared. COPYRIGHT: (C)2007,JPO&INPIT
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