| 摘要 |
PROBLEM TO BE SOLVED: To provide a smoke fire detector whose sensitivity is not changed even when a kind of smoke is changed and which detects the smoke with high sensitivity and with high accuracy. SOLUTION: In the smoke fire detector, a light sending part used to irradiate light at a smoke detection space, a first polarizer used to transmit only light on a first plane of polarization from among the light irradiated by the light sending part, a second polarizer used to transmit only light on a second plane of polarization via the smoke detection space, and a light receiving part used to receive the light via the second polarizer, are arranged on a straight line. The smoke fire detector comprises an optical rotation means used to turn the plane of polarization of the light between the first polarizer and the smoke detection space. COPYRIGHT: (C)2004,JPO
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