System for verifying detection of a fire event condition

#This invention relates generally to fire event sensing devices and, more particularly, to a system for verifying and improving the accuracy of detection of fire events by fire detection devices that utilize multiple fire event sensors so as to reduce false alarms.

#Various devices are known in the art which utilize more than one air condition sensor for sensing predetermined ambient air conditions indicative of a fire event. Although assumably effective for their intended purposes, existing fire event detection devices frequently sound false alarms. An ambient air condition sufficient to activate an alarm may, in fact, be caused by some event other than a fire. Therefore, existing devices often erroneously energize an alarm when a true fire event does not exist.

#Therefore, it is desirable to have a system for use with multi-sensor fire detection systems that reduces the threshold parameters of other sensors when a first sensor supposedly indicates a fire event and then energizes an alarm only if the fire event is verified by more than one sensor. Further, it is desirable to have a system that modifies predetermined threshold parameters if sensed air conditions at initial power-up indicate a likelihood of a climate-induced false alarm unless the parameters are modified.

#FIG. 1 is a block diagram of a preferred embodiment of a system for verifying the detection of a fire event condition;

#FIG. 2 is a flow chart showing the logic utilized by a programmable logic circuit according to the system of FIG. 1; and

#FIG. 3 is a flow chart showing the logic utilized by a programmable logic circuit according to the system of FIG. 1.

#A system for verifying and improving the detection of a fire event condition will now be described in detail with reference to FIGS. 1 through 3 of the accompanying drawings. Although the preferred embodiment described herein and as shown in FIG. 1 shows a system 10 utilized in conjunction with three sensors, it is understood that the system 10 is adaptable to be utilized with fire detection devices having a plurality of sensors. It is further understood that the system 10 described herein is not constrained to a particular fire event detection device, but rather is adaptable for use in any such device.

#A device employing the present system 10 would include a plurality of ambient air condition sensors 12, 14, 16 electrically connected to a power source 18 such as a battery (FIG. 1). During routine operation, the sensors 12, 14, 16 send a data stream 20 to a programmable logic circuit 24 according to a predetermined clock cycle. The clock cycle may be provided to the logic circuit 24 by a conventional resistor/capacitor (RC) pair 26. At predetermined time intervals of the RC pair 26, the logic circuit 24 transmits a signal 22 to each sensor to send input data to the logic circuit 24 for analysis. In other words, the logic circuit 24 regularly samples data from each sensor. The data stream (input data) 20 received from the sensors 12, 14, 16 includes measurements of respective ambient air conditions, such as smoke, heat, carbon dioxide, or other conditions depending on the sensors included in the detection device. The logic circuit 24 is adapted to generate signals whereby to initiate predetermined actions depending upon its analysis of the data stream 20, such as energizing an alarm 28 or modifying parameters, as to be described in detail below.

#The logic circuit 24 includes a plurality of threshold parameters, each parameter having a data type corresponding to a data type of an air condition measurement provided by a corresponding air condition sensor. Each threshold parameter has a predetermined value although these parameters may be modified in that the logic circuit is reprogrammable.