| 摘要 |
PURPOSE:To permit an user to decide abnormal condition such as imperfect combustion or the like before the operation of a safety device and reduce the influence of unevenness in the ion electric current of flames on a product, by a method wherein a value, in which a part exceeding a predetermined value is cut, is indicated in an analog type meter when the detected ion electric current is higher than the predetermined value. CONSTITUTION:When the ion electric current is conducted by the conductivity of a flame 10, the ion electric current of the flame flows through resistors R1, R2 and a voltage V1 is generated between ground and a signal A. When the signal A is inputted into an operational amplifier 12, the impedance conversion thereof is effected and, then, it drives a level meter 9 as the output B of the operational amplifier 12. The output signal B of the operational amplifier 12 is clamped by the resistor R4 and a Zener diode DZ1 in a driving circuit to prevent the level meter 9 from being applied with the voltage higher than a predetermined value. According to this method, a part which exceeds the predetermined value is cut by the Zener diode DZ1 when the voltage V1 has exceeded the predetermined value, in order to prevent a position, shown by the pointer of the level meter 9, from being different by the different lot of finished product. |
