| 摘要 |
PROBLEM TO BE SOLVED: To detect the flame of a combustor with high reliability by delivering the output signal from a first detection circuit as a final flame detection signal when the detection signal of an ultraviolet detector exhibits a quantity of UV- ray exceeding a specified level. SOLUTION: A first comparison circuit 41 is fed with the output voltage from an UV detection circuit 40 and a specified reference voltage V1 while a second comparison circuit 42 is fed with the output voltage from the UV detection circuit 40 and a specified reference voltage V2. When the first comparison circuit 41 makes a decision that the output voltage from the UV detection circuit 40 exceeds the reference voltage V1, i.e., an UV tube 2 detects a significant quantity of UV-ray, a selection circuit 46 selects the output signal from the second comparison circuit 42 based on the output signal from the first comparison circuit 41. When a decision is made that the output voltage from the UV detection circuit 40 is lower than the reference voltage V1, the output signal from an AND circuit 45 is selected based on the output signal from the first comparison circuit 41.
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