Fire alarm system
First Claim
1. A fire alarm system which comprises:
- a plurality of smoke detectors adapted to be installed in different locations, each smoke detector measuring the density of possible smoke in corresponding location as analog data and producing a corresponding smoke density digital signal indicative of the smoke density;
a receiver connected through a data transmission line to said smoke detectors so as to receive the individual density signals from the smoke detectors;
fire judging means included in the receiver for determining the presence of fires and fire locations only when the smoke density signal from the smoke detector in the corresponding location exceeds a reference density level and at the same time when such smoke density lasts over a reference time period;
said receiver including selection means for selecting said reference density level among a plurality of predetermined density levels of different values for each smoke detector as well as for selecting said reference time period among a plurality of predetermined time periods of different values for each smoke detector; and
alarm means responding to the determination of presence of fire by said judging means for issuing an alarm signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A novel fire alarm system with a plurality of smoke detectors which are adapted to be installed in different locations are connected through a data transmission line to a receiver where the smoke density signals transmitted from the respective smoke detectors and indicative of the density of smoke in the corresponding locations are processed for determination of fire presence. The receiver is provided with fire judging circuit which identifies the presence of fire only when the smoke density detected by any one of the smoke detectors exceeds a reference density level and when such smoke density lasts over a reference time period. Thus, the information from each smoke detector is analyzed with respect to the smoke density and the time period over which the smoke density of significant level lasts. Accordingly, a reliable detection of fire is effectuated. Also incorporated in the system is a selector by which said reference density level can be selected from a plurality of predetermined density levels of different values and by which the reference time period can be selected from a plurality of predetermined time periods of different values. Consequently, the criterion which is the combination of the smoke density and the related time period for determination of fire presence can be variably set depending upon the differing conditions of the locations under surveillance, enabling the system to be easily and successfully adapted for use in different fire monitoring conditions.
-
Citations
10 Claims
-
1. A fire alarm system which comprises:
-
a plurality of smoke detectors adapted to be installed in different locations, each smoke detector measuring the density of possible smoke in corresponding location as analog data and producing a corresponding smoke density digital signal indicative of the smoke density; a receiver connected through a data transmission line to said smoke detectors so as to receive the individual density signals from the smoke detectors; fire judging means included in the receiver for determining the presence of fires and fire locations only when the smoke density signal from the smoke detector in the corresponding location exceeds a reference density level and at the same time when such smoke density lasts over a reference time period; said receiver including selection means for selecting said reference density level among a plurality of predetermined density levels of different values for each smoke detector as well as for selecting said reference time period among a plurality of predetermined time periods of different values for each smoke detector; and alarm means responding to the determination of presence of fire by said judging means for issuing an alarm signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
Specification