| 摘要 |
PURPOSE:To provide a flame detecting circuit which prevents the occurrence of malfunction due to pulsation and has a rapid response time, by a method wherein flame detection is effected by cutting a pulse, the pulse width thereof is smaller than a predetermined value, out of pulses detected by a flame detecting means. CONSTITUTION:A pulse at a point B from a flame detecting part A is inputted to an input part CL1 of a first one-shot multi-vibrator 16 through an AND circuit 18, and similarily, the pulse at the point B is connected to one input terminal of an AND circuit 21 through a delay circuit consisting of a resistor 19 and a capacitor 20, and the output of the first one-shot multi-vibrator 16 is introduced to other input terminal of the AND circuit 21 through a NOT circuit 22. A resistor 23 and a capacitor 24 determine the width of a pulse generated by the first one-shot multi-vibrator 16, and similarily, a resistor 25 and a capacitor 26 determine the width of a pulse generated by a second one-shot multi-vibrator 17. This permits stable and reliable detection of the flame. |
