| 摘要 |
PURPOSE:To eliminate the need for a sliding part and to improve the reliability by providing a time difference measuring circuit which measures the time difference between an electric signal applied to an ultrasonic oscillator and the output signal of an ultrasonic detection part, and calculating the position of the ultrasonic detection part from said time difference. CONSTITUTION:The displacement transducer is equipped with the time difference measuring circuit which measures the time difference between the electric signal applied to the ultrasonic oscillator 2 and the output signal of the ultrasonic detection part 3. In this case, the detection output of a photodetector 32 is applied to a counter 8 through an amplifier 6 and a comparator 7 to stop counting operation. At this time, the counted value of the counter 8 corresponds to the time that an acoustic wave requires to travel from one end of a transparent medium 1 to the position of the ultrasonic detection part 3, so a signal processing circuit 10 calculates the position of the ultrasonic detection part 3 on the basis of said value. Consequently, no sliding part is required and the reliability is therefore improved. |
