| 摘要 |
PURPOSE:To double sensitivity and SN of a detector by utilizing both projected light and reflected light, by reflecting a projected light from a projector with an angle different from an incidence optical axis by a mirror surface part to absorb at the light absorbing part of the projector side and providing a photodetecting device between the projector and the light absorbing part. CONSTITUTION:The projected light I being a monitoring light beam emitted from the projector L and advanced straightly without colliding with smoke particles P is reflected at a mirror surface part M provided to a dark room wall W2 of opposite side of a dark room wall W1 referring to a space S as the reflected light D being the second monitoring light with the angle different from the incidence optical axis to absorb to the light absorbing part F provided at the wall W1. The photodetecting device R consisting of photoelectric transducer, etc. generating fire detecting signal receiving a scattered light T scattered by collision of the projected light I and the reflected D with the particles P is provided between the part F and the projector L and at a position where the secondary reflect light from the part F is not made incident. |
