| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect liquid level by detecting a top end edge of a container contains liquid to eliminate interference of a reflected wave from the liquid level. SOLUTION: A distance (height of a container 7) from a top end edge of the container 7 contains measured liquid that is detected by height sensors 12a, 12b, 12c to a detection probe 4 is determined by a central processor 13. A distance (height of liquid level 5a) from liquid level 5a to the probe 4 is calculated based upon a transmit/receive time of an ultrasonic which is sent from the probe 4 to the liquid level 5a in the container 7 and out put to the central processor 13 by a calculation circuit 20. Both height data of the liquid level and the height of the container 7 are compared and detecting condition of the probe 4 is changed and redetected under controlling of a retainer 14 by a control circuit 15 when both height data are coincided or the reflected wave is not received by an ultrasonic receiver 3. Thereby, the liquid level 5a is accurately detected. |
