| 摘要 |
PURPOSE:To detect a liquid level independently of operation of an object controller by detecting the difference of air temperature as resistance and voltage changes with a thermo-sensitive device. CONSTITUTION:When the liquid level is secured, that is, when a liquid level detecting self-heating thermo-sensitive device 10 is in the liquid, the output voltage of a liquid temperature detecting thermo-sensitive device 11 (voltage at a point (a)) is higher than the voltage at a point (b) because the output voltage of a temperature compensating operation circuit 12 (voltage at the point (b)) is used as a reference voltage. If the liquid level is lowered, the resistance of said thermo-sensitive device 10 is reduced suddently, and the voltage at the point (a) is reduced in accordance with this reduction. However, the output voltage of the circuit 12 is hardly changed because the thermo-sensitive device of the circuit 12 detects only the ambient temperature, and the voltage at the point (b) is stabilized, and therefore, the voltage at the point (a) becomes lower than that at the point (b), and the output of a comparator 13 is inverted, thereby detecting lowering of the liquid level. |
