| 摘要 |
PROBLEM TO BE SOLVED: To provide a flame detecting device capable of surely detecting flame even the combustion flame of small light quantity such as blue combustion flame, when the flame is detected by using a photodiode. SOLUTION: This flame detecting device comprises a backward voltage variable means 13 for switching backward voltage applied to the photodiode 9 from a small value to a large value by signal output from a current output adjusting portion 122 of a controller 12. The photo-electric current is increased by switching the backward voltage to the large value. In addition thereto, a load resistance value of a load resistance 151 is determined to be smaller than a limit resistance value of the photodiode itself to allow large photo-electric current to flow. Further a current limiting means 15 is mounted for limiting the maximum current to be less than an allowable maximum current value to prevent flowing of electric current over the allowable maximum electric current to the photodiode to complement them. The flame is detected by comparing the photo-electric current after current-voltage conversion, amplification and A/D conversion, with a determination value. COPYRIGHT: (C)2007,JPO&INPIT
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