| 摘要 |
PURPOSE:To detect stably a defect signal existing on a disc face and a defect signal mixed in a picture signal by detecting the envelope from a detected signal including a pulse formed defect signal and detecting the defect signal only through circuits such as differentiation and comparison or the like. CONSTITUTION:A reproducing signal supplied to an input terminal 21 and including a synchronizing signal a1, and defect signals a2, a3 and a4 is envelope- detected by an envelope detecting circuit 22 and outputted as defect detected outputs h1, h2 by an upward defect pulse detecting circuit 30 comprising a differentiation circuit 23, a comparator 24 and a monostable multivibrator 25 or the like. Further, the reproducing signal supplied to the input terminal 21 is inputted also to an inverse circuit 28 and outputted as a defect pulse h3 by a downward defect detecting circuit 29. |
