| 摘要 |
PURPOSE:To increase effectively the sensitivity of detection, by lowering the sensitivity at the rise area of waveform of a video signal to prevent assuredly the chatter and then carrying out a detection of defect with a signal having a high sensitivity of detection at the area after the rise where no fear exists for the chatter. CONSTITUTION:The B, C and D video signals 21, 22 and 23 are obtained through delaying elements 3-5 form the A video signal obtained by shifting a video signal 40 to the negative side by a certain extent. These signals 21-23 are supplied to comparators 7-9 to produce the output CMP11 signal 33, CMP signal 35 and CMP signal 36 respectively. The output of a comparator 6 which received a signal 20 is led to a timer 10, and control signals 28-30 are delivered from the timer 10. Based on these control signals, the sensitivity of detection is lowered to some extent at the rise area of waveform of the video signal to prevent assuredly the chatter with the signal 33. Then a detection is carried out for flaws with signals 35 and 36 having a high sensitivity of detection and in a binary coding way after the rise where no fear exists for the chatter. |
