| 摘要 |
PURPOSE:To make it possible to highly accurately detect micro flaw by subjecting a member, which has passed a test by comparing a defect echo with a primary decision level, to test based on a secondary decision level. CONSTITUTION:A primary decision circuit 3a compares an echo with a primary decision level and delivers a pass signal to a standard deviation calculating circuit 3b. The circuit 3b calculates the average value and standard deviation for all echo peak values lower than the decision level of members 2 to be inspected and delivers the calculated values to a set number decision circuit 3c. The circuit 3c delivers time average value and the standard deviation signal to a first decision circuit 3d when the number of the members 2 is smaller than a set number otherwise to a second decision circuit 3e. The circuit 3d compares a second decision level from an initial value setting circuit 37 with echo peak values lower than the primary decision level and makes a decision of failure and delivers a signal to a pass/fail processing circuit 3g if the latter is higher, otherwise makes a decision of pass. The circuit 3e multiplies the received standard deviation by a coefficient and adds the product to the average value thus determining a secondary decision level before making a decision of pass/fail similarly to the circuit 3d. |
