| 摘要 |
PURPOSE:To certainly detect a joint position even by inexpensive small constitution, by providing a pair of coils to the front and rear parts of a substrate in the longitudinal direction and moving both coils through a pipe by the substrate to compare the change in the inductances of said coils. CONSTITUTION:A pair of coils 4, 4' are provided to the front and rear parts of a substrate 2 constituted so as to be freely moved along the inside of a pipe 1 in the longitudinal direction on the same axis as the pipe 1. The lead wires 6, 6' of the coils 4, 4' are connected to a detection apparatus 7 for comparing inductances of a pair of the coils or the change amounts corresponding to said inductances while a display part (not shown in the drawing) and a comparison part (not shown in the drawing) are provided to the detection apparatus 7. By this mechanism, constitution can be miniaturized extremely inexpensively and made easy in operation and a joint position can be detected certainly. |
