Title:
FIRE ALARM SYSTEM
Document Type and Number:
Japanese Patent JP3307824
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To exclude the influence of noises in discriminating the stain of a smoke sensor outputting a value corresponding to a smoke density from its output value.
SOLUTION: A fire alarm system is provided with a high stain discriminating part 6 discriminating the stain which ascends the output value of the smoke sensor 1 and a low stain discriminating part 7 discriminating the stain which descends the value. The high stain discriminating part 6 repeats the comparison of the whole output values of the smoke sensor 1 within a prescribed time with a least upper bound value at every prescribed time. When the whole output values continuously exceeds the least upper bound value for the portion of a prescrived number, it is judged that the smoke sensor 1 is stained. The low stain discriminating part 7 repeats the comparison of the lowest output value within the output values of the smoke sensor 1 within the prescribed time with a low limit value at every prescribed time. Then, it is judged that the smoke sensor 1 is stained when the lowest output value continuously exceeds the lower limit value for the portion of the prescribed number. When the stain for descending the output value is discriminated, alarm which is different from that at the time of discriminating the stain for ascending the output value is issued.
More Like This:
| WO/2002/071361 | SMOKE DETECTOR |
| JP7364342 | Smoke detectors |
Inventors:
Masahiko Nobukuni
Yasuo Ishikawa
Tetsuya Maki
Yasuo Ishikawa
Tetsuya Maki
Application Number:
JP5788896A
Publication Date:
July 24, 2002
Filing Date:
March 14, 1996
Export Citation:
Assignee:
Nittan Co., Ltd.
International Classes:
G08B17/10; G08B17/00; G08B29/24; (IPC1-7): G08B17/10; G08B17/00; G08B29/24
Domestic Patent References:
| JP5325058A | ||||
| JP5242377A |
Attorney, Agent or Firm:
Hiroshi Arafune