| 摘要 |
PROBLEM TO BE SOLVED: To detect even flames at a distance by providing a reflection part which reflects a physical quantity detected by a flame detecting element toward the flame detecting element. SOLUTION: A concave mirror 9 which is equivalent to the reflection part is sectioned in a parabolic shape and provided in a cover 8 while having its concave part facing a detection area for flames so that the opening part of the concave mirror 9 is aligned with a flame detection window 8, and the flame detecting element 1 is provided at the light convergence position where the reflected light of the concave mirror 9 is converged. The flame detecting element 1 is in the concave part of the concave mirror 9 and the detection areaθ' of the flame detecting element 1 is therefore narrow. Radiant energy entering the concave mirror 9 from the flame detection window 8a, on the other hand, is reflected by the concave mirror 9 and gathered at the position of the flame detecting element 1, so the distance by which flames can be sensed becomes long. Thus, the light convergence position of the concave mirror 9 is set inward at a distance from the opening part, so the detection areaθ' is limited and unnecessary physical quantities of a halogen lamp, etc., are not detected, thereby obtaining the flame sensor which causes no misalarming.
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