Ultrasonic liquid-level meter

Abstract

Abstract PURPOSE:To prevent erroneous detection due to the lowering in the output of a receiver when the surface of a liquid is at a predetermined level, by sweeping a definite range without fixing frequency singly. CONSTITUTION:A triangular wave oscillator 10 oscillates an output signal having a saw-tooth wave and the output thereof is given to the control input of a voltage control oscillator (VCO) 12 to sweep oscillation frequency. For example, the VCO 12 oscillates while sweeps a range of 100kHz-1MHz and the output thereof is emitted as an ultrasonic wave from a transmitter 16 and, as a result, a direct wave D and a reflected wave R propagate through the liquid 20 in a pipe to be received by a receiver 24. This ultrasonic wave is converted to an electric signal which is, in turn, inputted to an integrator 28 through a band- pass filter 26 to be detected as the total energy of the receiving signal during one sweeping period. Continuously, said signal is inputted to a comparator 30 and, when said signal is judged to be larger than a threshold value Vt, the comparator 30 outputs an H-level signal to give the same to an alarm 32. Therefore, the alarm 32 displays or informs that the height of the surface of a liquid is a predetermined value or more.

Inventors

• 👤 Naoyuki Omatoi

Bibliographic Details