| 摘要 |
PROBLEM TO BE SOLVED: To provide a field identification circuit which conducts stable field identification and controls an increase in circuit size, too, even if the input timing of a synchronizing signal fluctuates. SOLUTION: The circuit is provided with a delay portion 4 to output a delay signal VDDEL by delaying a vertical synchronizing signal VD, a VD signal differential pulse preparing portion 5 to prepare a VD signal differential pulse corresponding to a one-sided edge of the VDDEL, a field identification signal polarity regulating portion 6 to get a horizontal synchronizing signal HD and the VDDEL as inputs and to prepare a differential pulse corresponding to the one-sided edge of the VDDEL once per 2 fields by sampling an H level or an L level of the HD at the timing of the VDDEL, and a field identification stabilizing portion to prepare the field identification signal based on the VD signal differential pulse outputted by the VD signal differential pulse preparing portion and to regulate the polarity of the field identification signal based on the differential pulse outputted by the field identification signal polarity regulating portion. COPYRIGHT: (C)2007,JPO&INPIT
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