| 摘要 |
PURPOSE:To perform length measurement of high accuracy making use of the signals associated to the time until the ultrasonic wave signal generated in a magnetostrictive wire reflects and reaches a receiving means. CONSTITUTION:When an excitation pulse is applied to an exciting means 2, an ultrasonic wave signal is generated in a magnetostrictive wire 1 by so-called Joule effect and this propagates toward one end of the magnetostrictive wire 1. This ultrasonic wave signal reflects at one end 11 of the magnetostrictive wire 1 and returns to the exciting means 2 side. If it is assumed that the ultrasonic wave signal is generated within the magnetostrictive wire 1 at the same instant of applying the excitation pulse PE to the exciting means 2, the time width signal having the time width t proportional to the measuring length l may be obtained from the output end of a flip-flop circuit FF. Hence, by counting this time width t, the measuring length l may be measured. |
