Position Detecting Device

摘要

A highly accurate yet readily manufactured device for detecting positional displacements, for example, in various indicating and recording instruments, detects a displaced position by generating an ultrasonic signal in a magnetostrictive wire or rod 1 and measuring the propagation time of the signal generated. The device includes an exciting means 4 to generate an ultrasonic signal in the wire, first and second receiving means 2, 3 to receive the ultrasonic signal generated in the magnetostrictive wire by the exciting means, a means 5 for changing the distance between the exciting means and the receiving means in accordance with a mechanical displacement, and circuitry for producing a signal representative of the mechanical displacement by computing two signals related to the times required for the generated ultrasonic signal to reach the first and second receiving means, respectively along lengths I1 and I2. In an alternative arrangement (Figs. 15, 16, not shown), only one detecting means (20) is employed, the times being respectively for the signal to travel to the detecting means (20) and for the signal to be reflected at the opposite end (11) of the wire to the detecting means (20) i.e., along lengths I1 and I1 + 2I2. The device may also be used to monitor liquid levels (Fig. 6, not shown) and differential pressures (Fig. 7, not shown).