| 摘要 |
PROBLEM TO BE SOLVED: To provide an extinction type smoke sensor, capable of discriminating a fire with high accuracy, by eliminating effect of a noise source.SOLUTION: The extinction type smoke sensor includes: a smoke detection space 5; an optical path 7 for smoke detection formed to get across the smoke detection space 5; an optical path 9 for compensation; a light emitting element 11; a light receiving element 13 disposed so as to be able to receive light which passed through the optical path 7 for smoke detection and the optical path 9 for compensation; a shutter unit 15 provided at the optical path 7 for smoke detection for switching light shielding and light transmission of the passing light; and a fire discriminator 17a which uses the amounts of light received by the light receiving element 13 as a result of light shielding and light transmission at the optical path 7 for smoke detection by the shutter unit 15 in a normal state as a first and a second reference values, uses the amounts of light received by the light receiving element 13 as a result of light shielding and light transmission at the optical path 7 for smoke detection by the shutter unit 15 in a monitoring state as a first and a second monitoring values, determines a change rate in the amount of light received by the light receiving element 13 based on the first reference value and the first monitoring value, and performs fire discrimination based on the change rate, the second reference value, and the first and second monitoring values. |
