| 摘要 |
PROBLEM TO BE SOLVED: To provide a photoelectric smoke sensor that reduces false alarms due to large particles such as steam. SOLUTION: The photoelectric smoke sensor 1 includes a smoke detection space 27, a light trap 25, a light emitter 21, a light receiver 23 for receiving scattered light, and an optical stand 19 holding the light emitter 21 and the light receiver 23 and blocking direct light traveling from the light emitter 21 to the light receiver 23. The photoelectric smoke sensor includes: a first smoke flow passage forming member for forming a first smoke flow passage 11 extending across an upper part of the smoke detection space 27, a second smoke flow passage forming member forming a second smoke flow passage 13 extending across a lower part of the smoke detection space, and a smoke introduction passage 29 that introduces smoke by communicating the first smoke flow passage 11 with the upper part of the smoke detection space 27, or the second smoke flow passage 13 with the lower part of the smoke detection space. A difference in length is provided between the first smoke flow passage 11 and the second smoke flow passage 13. A differential pressure between the first smoke flow passage 11 and the second smoke flow passage 13 caused by the difference in length between the flow passages is used to introduce smoke into the smoke detection space 27 via the smoke introduction passage 29. COPYRIGHT: (C)2011,JPO&INPIT |
