| 摘要 |
PURPOSE:To reduce the range of the change of a liquid level at the time of control by using detecting signals supplying upper and lower limits and other detecting signals. CONSTITUTION:In order to perform step control, detecting signals from four sensors 1-4 are inputted to a control circuit 10. The control circuit 10 for controlling a liquid level by opening/closing valves 5-8 determines the base operation status of these valves 5-8 by the detecting signals from two sensors 1, 4 and controls the valve 7 by the detecting signals from other two sensors 2, 3 to keep the liquid level at an objective level through two kinds of detecting signals. |
