| 摘要 |
PURPOSE:To shorten a measurement time, and also to execute easily a measuring operation by installing in advance probes of a necessary number at a prescribed position on the outside circumference of an object to be measured, and executing a measurement by switching successively transmission and reception of these probes. CONSTITUTION:Probes 21a-28a, 21b-28b are made to contact by pressing to points P0-P7, P'0-P'7 in order shown in the figure, in the circumference of an object to be measured shown by a section 1. In switching devices 12-14, a contact switching is executed basing on signals G1-G3 from a switching control circuit 15. A signal C1 and a signal C2 are a receiving signal and a transmitting signal, respectively. By switching suitably the switching devices 12-14, a propagation time in the diameter opposed position of the object to be measured 1, a propagation time in a 90 deg. position, and a propagation time in 22.5 deg. position are measured, and a shape and a position of a defective part are detected basing on a ratio of this measured value and a reference propagation time measured value. |
