| 摘要 |
PROBLEM TO BE SOLVED: To provide a smoke sensor of hardly generating an erroneous announcement and a non-fire notification, while simplifying or omitting a labyrinth. SOLUTION: A sensor output processing part 2 changes an instantaneous value of an output signal Vout transiently in response to fluctuation of an input current Iin. An arithmetic processing part 3 has an AD converter 9 for converting the output signal Vout input from the sensor output processing part 2 into a digital value, and a determination circuit 10 for determining the presence of smoke in a detecting space, based on an output from the AD converter 9. In the AD converter 9, the output signal Vout is sampled twice in a transition response period of the output signal Vout with respect to the input current Iin, the instantaneous values of the output signal Vout in respective timings serve respectively as the first and second measured value. The determination circuit 10 finds a difference between the measured value and the second measured value, and determines the presence of the smoke in the detecting space, by comparing a difference value with a prescribed threshold value. COPYRIGHT: (C)2010,JPO&INPIT
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