| 摘要 |
PURPOSE:To discriminate an odd number and even number fields by using a fact that a time interval between a horizontal synchronizing signal appearing finally in the field and an equalizing pulse appearing first during a vertical fly-back line deleting period is different according to the odd number and even number fields. CONSTITUTION:By a synchronizing separating circuit 1, composite sunchronizing signals (a) and a' and a vertical synchronizing signal (b) are separated, and the composite synchronizing signals (a) and a' are inputted to a pulse detecting circuit A composed of an one-shot multi 2 and a binary output circuit 3. The detecting circuit A, when it enters the vertical fly-back line deleting period, inverts the output at every time the equalizing pulse is received, and the action continues until the horizontal synchronizing pulse of 1H appears during the vertical fly-back line deleting period. When the vertical synchronizing signal (b) is sent from the separating circuit 1, the output of the detecting circuit A at the time point is stored into a latch circuit 4. Since the signal stored by the latch circuit 4 is the level different at the odd number and even number fields without fail, thus, the odd number and even number can be discriminated. |
