| 摘要 |
PURPOSE:To detect the size of a defect in a material to be inspected correctly with a smaller and low-cost apparatus by a method wherein an analog signal reflected from an internal defect or the like is stored temporarily and the maximum value thereof is detected at each frequency of sampling to be converted into a quantization signal. CONSTITUTION:A time-sharing analog signal reflected from inside a material to be inspected by an ultrasonic wave being radiated synchronizing a clock from a clock circuit 1 is applied to a peak detection circuit 6 via a receiving circuit 5 to store the maximum value thereof into a capacitor C temporarily being held for a fixed time. Receiving a clock command from the circuit 1, an A/D conversion circuit 8 operates to quantize the maximum value of the analog signal. On the other hand, the clock from the circuit 1 is applied to the circuit 6 through a delay circuit 7 and after the end of the operation of the circuit 8, it provides a command to a switch S. With the operation of the switch S, an electric charge stored in the capacitor C is discharged quickly to arrange the preparation for the sebsequent analog signal sampling. This enables accurate detection of a defect with a handy circuit without use of a costly and large high speed A/D converter or the like. |
