| 摘要 |
PROBLEM TO BE SOLVED: To provide a flame detecting circuit of a combustion device of high safety, for detecting abnormality of a resistance for flame detection without increasing the number of components of the circuit. SOLUTION: This flame detecting circuit includes a resistance 10 for voltage dividing, dividing voltage with the resistance 3 for flame detection in non-combustion, and determines the abnormality of the resistance 3 for flame detection on the basis of a voltage dividing ratio with the resistance 10 for voltage dividing. When the resistance 3 for flame detection is failed, and a resistance value is increased or the resistance is kept in an opened state, voltage drop in the resistance 3 for flame detection is increased even though sufficient current does not flow due to shortage of oxygen, which causes incorrect detection that the combustion is normally performed. But by applying the above constitution, the abnormality of the resistance 3 for flame detection is detected before a combustion operation is started, so that the combustion device is used in safety. COPYRIGHT: (C)2010,JPO&INPIT |
