| 摘要 |
PROBLEM TO BE SOLVED: To accurately measure the space size from a reference point of a tank to the liquid surface in the tank even if there is an air bubble on the liquid surface, and to easily align the reference of the measuring instrument to the reference point of the tank. SOLUTION: The depth measuring instrument comprises a weight 11 fitted atop of a cord, an electric motor 2 which drives a take-up unit 16 for taking up the cord, a pulse generating means which generates one pulse each time the cord moves by unit length, a driving current switching means 19 for the electric motor, and a tension detecting means 20 for the cord measures the depth by moving the weight from the reference point with its weight by switching the driving current of the electric motor. The tension of the cord is monitored by the tension detecting means 20, pulses generated by the pulse generating means are counted as the cord moves until the value of the tension varies, the number of the counted pulses is multiplied by the unit length of the cord.
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