| 摘要 |
PURPOSE:To make it possible to derect the existence or nonexistence of a flame and the density of oxygen in the burner by a metod wherein the rate of increase of an ion current after the initiation of combustion of the burner is varied between a predetermined period of time and after a lapse of the predetermined time in the captioned apparatus using ion current detecting means. CONSTITUTION:When a heater or the like is ignited, a flame is formed on a burner head 2 and at the same time, a timer 5 released from a reset signal E is operated. Consequently, an ion current flows through the burner head 2 via a flame rod 1 due to the flame and then joins a high level DC signal from the timer 5 to be converted into a high level voltage signal A through a resistor 8. The voltage signal A is impressed upon a voltage comparator 13 after it is converted into a voltage signal B through a protective resistor 10. In this case, the signal A is made to become associated with the density of oxygen in the heater when the timer 5 generates a low level DC signal F after a lapse of a predetermined time, that is, after a lapse of time in which the ion current is stabilized, while when the voltage signal B decreases lower than a reference voltage, a signal D is interrupted to thereby alarm that the heater is short of oxygen. |
