Patent US4697172A successfully refreshed from Google Patents.
US4697172A
Expired / Lapsed
US
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Fire alarm system
Assignee: Nittan Co Ltd
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Filing: 1985-09-25
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Granted: 1987-09-29
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Expires: 2005-09-25
Abstract
Abstract A fire alarm system employing multiple sensors can accurately and quickly respond to real fires with an alarm signal and prevent issuance of a false alarm due to noise or the like. A pair of decision circuits in a fire signal receiver receive fire detection signals from respective sensors and produce fire occurrence signals representing a first level of probability that a fire has occurred and decision signals representing a second lower level of probability that a fire has occurred. A fire alarm is issued when a fire occurrence signal has been outputted by any one of the decision circuits or when a decision signal is simultaneously outputted by both decision circuits.
Inventors
- 👤 Tetsuo Kimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:58
CPC Classifications
G; G08; G08B; G08B17/00
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
150 words
In a fire alarm system comprising a plurality of fire sensors installed in a monitoring area and a fire signal receiver which issues a fire alarm in response to fire detection signals outputted by said fire sensors, the improvement wherein said receiver comprises: a plurality of decision means receiving said fire detection signals from said fire sensors for producing fire occurrence signals representing a first level of probability that a fire has occurred and decision signals representing a second, lower, level of probability that a fire has occurred; and fire alarm means for issuing a fire alarm when one of said fire occurrence signals is outputted or at least two said decision signals are produced, wherein said fire sensors comprise on-off type fire sensors, and each of said decision means produces a fire occurrence signal when the respective fire sensor has operated plural times within a predetermined period of time.
Claim 2
Dependent Claim
150 words
In a fire alarm system comprising a plurality of fire sensors installed in a monitoring area and a fire signal receiver which issues a fire alarm in response to fire detection signals outputted by said fire sensors, the improvement wherein said receiver comprises: a plurality of decision means receiving said fire detection signals from said fire sensors for producing fire occurrence signals representing a first level of probability that a fire has occurred and decision signals representing a second, lower, level of probability that a fire has occurred; and fire alarm means for issuing a fire alarm when one of said fire occurrence signals is outputted or at least two said decision signals are produced, wherein said fire sensors comprise on-off type fire sensors, and each of said decision means produces a fire occurrence signal when the respective fire sensor has operated plural times within a predetermined period of time.
Claim 3
Dependent Claim
155 words
In a fire alarm system comprising a plurality of fire sensors installed in a monitoring area and a fire signal receiver which issues a fire alarm in response to fire detection signals outputted by said fire sensors, the improvement wherein said receiver comprises: a plurality of decision means receiving said fire detection signals from said fire sensors for producing fire occurrence signals representing a first level of probability that a fire has occurred and decision signals representing a second, lower, level of probability that a fire has occurred; and fire alarm means for issuing a fire alarm when one of said fire occurrence signals is outputted or at least two said decision signals are produced, wherein said fire sensors comprise analog type fire sensors producing analog data, and wherein each of said fire sensors comprises means for integrating analog fire data signals for producing a fire occurrence signal from the integration of said analog data.
Claim 4
Dependent Claim
155 words
In a fire alarm system comprising a plurality of fire sensors installed in a monitoring area and a fire signal receiver which issues a fire alarm in response to fire detection signals outputted by said fire sensors, the improvement wherein said receiver comprises: a plurality of decision means receiving said fire detection signals from said fire sensors for producing fire occurrence signals representing a first level of probability that a fire has occurred and decision signals representing a second, lower, level of probability that a fire has occurred; and fire alarm means for issuing a fire alarm when one of said fire occurrence signals is outputted or at least two said decision signals are produced, wherein said fire sensors comprise analog type fire sensors producing analog data, and wherein each of said fire sensors comprises means for integrating analog fire data signals for producing a fire occurrence signal from the integration of said analog data.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-09-28 | 1991-03-30 | 1991-09-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-09-28 | 1995-03-30 | 1995-09-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-09-28 | 1999-03-30 | 1999-09-29 | $7700.00 | Window Closed / Lapsed |