| 摘要 |
PURPOSE:To detect an oxygen deficiency state in a stable oxygen concentration without influence from the amount of combustion by installing a compensating part which changes the detected level of a detecting circuit in response to the amount of combustion at a combustion part in the detecting circuit sensoring the change in the output of a detecting element. CONSTITUTION:A variable resistor 5 of which resisting value is varied in connection with an adjusting part 4 for the amount of combustion functions as an adjusting part for the detected level of oxygen deficiency. when the output by an NTC thermistor 13 is lower than a reference voltage, a buzzer 22 is operated to induce ventilation. When an oxygen deficiency state occurs in the maximum combustion condition, though the resistance of the thermistor 13 is rather higher, the resistance of the resistor 5 which determines the reference voltage used for comparison with the output of the thermistor 13 at a comparator 21 becomes also high. Conversely, when the oxygen deficiency state occurs in the minimum combustion condition, though the resistance of the thermistor 13 is rather lower, the resistance of the resistor 5 is also low, and therefore the detected level of oxygen deficiency at that condition is almost the same as that in the maximum combustion condition. Therefore, in either case, the buzzer 22 is operated in almost the same oxygen concentration. |
