| 摘要 |
PROBLEM TO BE SOLVED: To detect a flaw without being subjected to the influence of an external noise by a method wherein, by means of the C-scope display of a flaw in a metal plate material, outputs of whether a flaw exists or not covering two cycle portions are ANDed and a plurality of cycle portions are added so as to be used as data for a display. SOLUTION: N pieces of ultrasonic probes are arranged in the direction of the width of a rolled metal plate or the like, ultrasonic waves are transmitted and received periodically in a direction perpendicular to the width, and outputs A, by a flaw judgment circuit, at two levels compared with a prescribed slice level are obtained. The outputs A are stored as a matrix of N pieces per row. When the same outputs A in a next cycle are obtained, a logical product corresponding to every element in a matrix is stored as outputs B by an AND circuit. Every black circle indicated by an arrow in the outputs A indicates a random external noise, and it is excluded in the outputs B. The outputs B are added regarding every element in the matrix at every M+1 cycle of the transmission and reception operation of the ultrasonic waves so as to be stored as outputs C by an addition register circuit. On a C-scope, the outputs C are luminance- or density-modulated according to their content so as to be displayed. A luminance or a density corresponds to the magnitude of a flaw so as to be used as information suitable for flaw detection. |
