| 摘要 |
PURPOSE:To prevent the mutual interference of span zero point adjustment by providing the subject device with means for measuring the distance between a transmitter-receiver and a position to be measured, and means for computing the first reference length and the second reference length from the transmitter-receiver in a predetermined relationship. CONSTITUTION:A starting signal is supplied from a terminal 15 to a ultrasonic wave generating circuit 16 and a counter 17. The circuit 16 generates a ultrasonic wave pulse, and excites a emitter 18 and radiates a ultrasonic wave pulse. The reflected wave from a position 12 to be measured is received by a receiver 19, and the received pulse is detected by an amplification detection circuit 21. On the other hand, the counter 17 stops the counting of the clock pulse from a terminal 22 by receiving the output of the above described pulse. The distance d from the transmitter and the receiver 18 and 19 to the position 12 to be measured is supplied from the counter 17 to a computing means 23. To the computing means 23, there is supplied the first reference length D2 as a value corresponding to zero point, and as a position corresponding to 100%, there is supplied the second length D2. From the length D1 and D2 the ratio of (D1-d)/(D1-D2) is computed in the computing means 23. |
