| 摘要 |
PURPOSE:To remove influence due to the distribution capacity of electric wire, by connecting the output of a rectangular wave voltage generator with a liquid-level detection electrode through a current detection circuit detecting the current after elapsing a fixed time from an inversion time of output of rectangular wave. CONSTITUTION:The output of a rectangular wave voltage generating circuit 8 being zero in mean value is iputted electric wires 5A, 5B through an electric current detection circuit 9 consisting of a resistance 9a, a capacitor 9b and electrodes 4A, 4B having different lengths are connected with the end of the wires 5A, 5B and then, these are arranged in a water vessel 7. Moreover, the capacity C9b of the capacitor 9b of the circuit 9 is set for a distribution capacity CO of the wires 5A, 5B so as to be C9b>>CO. By thus constitution, when the water level of a water bath 7 is W1, the current by the rectangular wave voltage is flowed through the capacitor 9b and is not flowed to the resistance 9a. Further, when the water level is W2, the current is flowed to the resistance 9a and voltage is generated on both ends of the resistance 9a and as a result, it is known that the water level is reached W2 by detecting this voltage. |
