| 摘要 |
PURPOSE:To contrive to eliminate the repetition of fruitless firing action and consequently to improve the safety and reliability by a method wherein automatic lockout action is performed under the condition that recycling action is repeated a set number of times for a certain fixed period of time for some cause or other. CONSTITUTION:With every change of output of a comparator 3, a signal with H level output is read into a shift register 4. When the predetermined times of shifting are repeated, the state of shifting is returned to its first stage by means of the reset pulse issued by an oscillator 5. When the number of times of change of the output level of the comparator 3 for the certain fixed period of time exceeds the set number of times, the output end of the comparator 3 has H level output, resulting in conducting a transistor Q1. Consequently, the voltage at the point (b) becomes very low and accordingly the output of the comparator 3 is kept at H level (the state that no flame is detected) regardless of the state of a flame detector CdS and, as a result, the lockout action is performed by a lockout means comprising a safety switch heater SSH and safety switch SSW. |
