Patent Publication Number: US-7221260-B2

Title: Multi-sensor fire detectors with audio sensors and systems thereof

Description:
FIELD OF THE INVENTION 
     The invention pertains to systems and method for monitoring regions. More particularly, the invention pertains to such systems and method which incorporate audio feedback information indicative of alarm conditions. 
     BACKGROUND OF THE INVENTION 
     It has been recognized that early detection of fires has great merit. The earlier a fire is detected, the earlier the fire department is called, and the earlier the department can start to fight the fire. However, attempts to increase the speed of detection can also run the risk of increasing the number of false positive alarms. So increasing the speed of detection while minimizing false positive alarms, or lowering the level of false positive alarms is very desirable. 
     Smoke detectors indicate where there is smoke in a region. As smoke spreads away from a fire, only a few of the alarming smoke detectors are near the fire. The faster the location of the actual fire can be located, the faster the fire fighters can mount an attack. It is desirable to be able to differentiate between smoke and fire in a system that is in alarm. 
     Another problem at fire scenes is that the location of trapped civilians and of fire fighters is often not known. It often is the case that fire fighters are unsure about whether there are trapped civilians in a building. Civilians are usually not issued special safety equipment before an emergency to protect them in an emergency. When in involved buildings, fire fighters are often out of contact with fire commanders due to radio interferences and blind spots. 
     There this is a continuing need to be able to locate and monitor the positions of fire fighters and victims in fires, explosions, and other emergencies as well as to locate and diagnose fires. Further, there is a continuing need to be able to detect and track fire progress in a region being monitored. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an ambient condition detector in accordance with the invention; 
         FIG. 2  is a block diagram of a monitoring system which incorporates the detector of  FIG. 1 ; 
         FIGS. 3A ,  3 B and  3 C illustrate one form of processing of received audio; and 
         FIGS. 4A ,  4 B and  4 C illustrate another form of processing of received audio. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     While embodiments of this invention can take many different forms, specific embodiments thereof are shown in the drawings and will be described herein in detail with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
     Embodiments of the present invention detect the sound of fire or flame. An audio transducer in an ambient condition detector could be used to detect such sounds. 
     The detector&#39;s on-board processor could be loaded with characteristic flame signatures. When the detector is able to detect some sounds that match the signatures, it could go into alarm. 
     If lower levels of false positive alarms are desired, the detector could wait for confirmation from other local sensors such as flame, smoke or temperature before the detector itself goes into alarm. If few false positives, but earlier detection are desired, the first sensor to alarm could increase the sensitivity of the other sensors. This heightened mode of sensing could cause more sensitive, and quicker reactions in the other sensors. If this heightened sensing mode showed a second sensor in alarm within a set time period after the first sensor alarmed, the detector could then alarm and notify the region&#39;s protection system. If a second sensor doesn&#39;t alarm within a set period, the detector could revert out of the trouble state which was caused by the first alarm, to a normal state. 
     Audio signals could be used in detecting flames in the early stage of development. Audio signals could also be used to adjust operational parameters of detectors monitoring the region. 
     Audio transducers can also be used in differentiating between smoke and fire. In addition, if a heat sensor is incorporated into the detector and periodically outputs temperatures during a fire rather than just alarming at a set alarm point, that information could be useful to fire fighters. With a graphical user interface, the extent of the smoke cloud can be evaluated and, the extent of the flames, smoke and the rising temperatures in the region can be visually displayed. Additional information about fire location that fire fighters could receive would help them to suppress the fire more quickly. 
     In one embodiment, fire detectors could incorporate audio transducers. Civilians or fire fighters could also use the microphones to identify their location, to report that they are in trouble, or to convey information about the fire or other information back to the fire commander. Their location would be easily determined by identifying the transducer that picks up their message at the loudest level. If fire sound is loud at that location, sound filtering could be activated to filter out fire sounds when voices were heard. 
     Fire teams could periodically call out an identifying code. This information would be picked up by a speech recognition module in the region&#39;s monitoring system to keep the incident commander informed as to the team&#39;s whereabouts. The commander could also use traditional radios, or the PA system, to call back to fire teams or victims and inform them of where they are, and how they need to navigate to get to the fire, out get out of the building. 
     Audio signatures of different types of fires could be pre-stored in the individual detectors, and also at the fire or regional monitoring system. The detectors, as well as the monitoring system could incorporate processing circuits to process the audio, such as the fire sounds. The system would not activate until a combination of two smoke detectors, sprinkler flow sensors, other fire sensors, or the audio sensors had gone into alarm. Only when the system was activated could the monitoring system start to access sound sent to it from individual speaker/microphone assemblies. This feature would assure that there is no intrusion into individual privacy in a region or building. 
     Once the system was activated, the detectors could start sending signals back to the system for situation assessment analysis, reporting on the user display, and allowing fire fighters direct access to sounds picked up by the microphones. The system, could then gather sounds from all the spaces where there are such detectors on a regular basis. 
     In the presence of a fire, there may be a great deal of noise. A speech recognition module might have difficulty understanding what was being said, even with sound filtering to filter out fire noise. A replay mode could then be engaged that allowed a listener to reply a recording of the last three items in a certain speaker zone. The zone where the activity is happening could light up on a visual user interface. 
     Each recording could be time stamped to allow easy differentiation. Such a manual mode could be an alternate to automatic signal processing. The manual mode allows fire commanders to listen directly to the sounds the fire is making in different spaces, and carry out diagnosis by identifying individual sounds. 
     A user interface could include a touch screen or an array of buttons to identify different areas and cluster transducers. A system in accordance with the invention could have an automatic user interface that would show the location of fire teams, or unidentified persons, in the location that their sound was last detected. An audio tracking algorithm could also be used to track each source of sound and show their progress as they move through the building. This display would help fire commanders keep up to date on where their fire teams are, and where they have come from in the facility. It would also identify probable civilians, their location, and whether they are still moving. 
     The detectors would fail at some point as the space they are in burns. A temperature sensor could be included to report this fact. This sensor could provide readings once the system is activated, or could act as a continuous monitor of building temperatures. Once the system is activated by a smoke sensor or other sensor, it could start reporting temperatures and track where temperatures are rising. The actual rising temperatures during a fire could be recorded by location and displayed for fire commanders. 
     This heat sensor could also act as a detector monitor. If a heat sensor failed after the system had been activated, the system could assume that it had failed due to being overheated. The system would also be able to call that conclusion into doubt if relatively low temperature readings had been recorded just prior to failure. The system could partially self-diagnose by checking to see if other detectors on the same power source or data lines are also out of operation. 
     Alternatively, the temperature sensing capability in such detectors could be used for building operation purposes in non-alarm states. Temperature variation and occupant dissatisfaction with temperature are two problems that facility managers face. The temperature sensors in detectors could be used to continuously monitor environmental conditions in the region or building. This would be useful since there might be more temperature sensors in the detectors than there are thermostats in zoned buildings. Very few of the thermostats are able to transmit their readings to a central location. 
     An integrated building control and fire safety system could monitor room temperatures at many locations, determine where temperatures are drifting from set points, and help diagnose deficient performance in HVAC (heating, ventilation, and air conditions) air delivery. Since the balancing, or thorough adjustment, of HVAC systems is expensive and happens infrequently in large buildings, gaining information on HVAC air delivery performance could enable making minor adjustments to improve performance. This ability would help facility managers to more consistently deliver the temperatures their customers want. 
       FIG. 1  illustrates a block diagram of a detector  10  in accordance with the invention. Ambient condition detector  10  incorporates a fire or smoke sensor  12 , an audio input transducer, such as a microphone,  14  and an optional temperature sensor  16 . Outputs of the sensors  12 ,  16  and transducer  14  are coupled to detector control circuits  18 . 
     The circuitry elements  12 – 18  can be carried in a housing  20  and located in a region R to be monitored. Control circuits  18  communicate with a remote monitoring system via communications medium  22  which could be wired or wireless without limitation. 
     As noted above, outputs from audio transducer  14  can be processed by control circuitry  18  to detect sounds of flame or fire. Additionally, the thermal sensor  16  can be used as a supplement to outputs from the smoke sensor  12  and audio transducer  14 . 
     Speech input from individuals in the vicinity of the detector  10  could be detected by transducer  14  and processed in control circuits  18 . The outputs pertaining to detected speech could be coupled by medium  22  to monitoring system  24  to provide feedback as to the location of responders such as fire fighting personnel in the region being monitored. 
     The outputs from the audio transducer  14  can be analyzed by the local control circuits  18  or the monitoring system  24  and compared to normal expected sounds in the area of the detector  10 . The response of the detector  10  can be altered dependent on the received sounds and the patterns of the sounds. Alteration can include alarm thresholds, changing filtering or smoothing characteristics, delays or the like all without limitation. 
     If the received audio indicates that the region in the vicinity of the detector  10  is occupied and there are no indications of a fire or other alarm condition, control circuitry  18  can reduce the sensitivity to signals received from smoke sensor  12  or thermal sensor  16  to reduce nuisance alarms or false positives. The outputs from audio transducer  14  can also be used as supplemental inputs indicative of occupancy or activity in the region of detector  10  to secure the lighting or HVAC systems. Alternately, when the incoming audio indicates that the vicinity of the detector is not occupied, the sensitivity can be increased. 
       FIG. 2  is a block diagram of a system  30  for monitoring a region R. A plurality of detectors D 1  . . . Dv corresponding to the detector  10 , are mounted in the region R. The detectors D 1  . . . Dv are in bi-directional communication with a processor  32  of the system  30 . System  30  could, for example, be part of a fire alarm control panel. 
     The processor  32  is coupled to a visual display  34  and an audio output transducer, such as a speaker  36 . Responder inputs can be received at processor  32  via a touch screen on the display  34 , keyboard switches all and the like, all without limitation. 
     The speech of fire fighters in the region R in the vicinity of detectors D 1  . . . Dv could be sensed using the respective audio transducers  14  and signals indicative thereof provided to processor  32 . Such signals could specify the location of the various fire fighters which in turn could be presented on display  34 . 
     The system  30  could be designed so that it would not activate and start monitoring outputs from the audio transducers  14  until a combination of two or more ambient condition detectors such as smoke detectors, sprinkler flow sensors, other fire sensors or other audio sensors have gone into alarm. The processor  32  can also incorporate speech recognition software to improve the ability of an individual in the vicinity of speaker  36  to understand what is being said even in the presence of noise from the fire. 
     Processor  32  can incorporate location defining software responsive to the outputs of detectors D 1  . . . Dv to show the location of smoke, fire, firefighting personnel or unidentified persons in the region R. 
     Audio tracking can be implemented at processor  32  to respond to changing inputs at the transducer  14  and a respective detectors D 1  . . . Dv as firefighting personnel or other individuals move through the region R being monitored. Additionally, processor  32  can respond to failures in the respective thermal or temperature sensor  16  as the fire burns or destroys the respective detectors. 
     It will be understood that the audio signals from the respective transducers  14  can be processed or filtered for example to eliminate substantially constant noise from adjacent machines or external sources. The details of such processing are not limitations of the present invention. 
     In one embodiment, the audio processing software in processor  32  could ascertain whether or not signals being received from the respective detectors D 1  . . . Dv were indicative of normal, non-alarm indicating audio associated with such detectors or alternately whether the audio being received indicated that the space adjacent the respective detectors was unoccupied or whether sounds emanating therefrom were indicative of an alarm condition. Where the adjacent spaces are relatively quiet, sensitivity of the respective detector could be increased. Where normal activity is indicated in the vicinity of the various detectors vis-à-vis, sensitivity can be decreased. Depending on the profile or signature of the audio being sensed, specific adjustments to the respective detector sensitivity could be made. 
       FIG. 3A , illustrates representative audio signals, such as might be present in a region being monitored, and, incident on the audio transducers, such as for example microphone  14 . Such signals could be processed directly or rectified and then processed.  FIG. 3A  is an unrectified signal.  FIG. 3B  is a rectified representation of  FIG. 3A .  FIGS. 3A and 3B  further illustrate representative processing of the incident audio where a ratio of a minimum value to a maximum value is formed. In  FIG. 3C , rectified audio has been processed by forming a ratio of minimum to maximum values to take out noise or audio of very short duration. 
       FIGS. 4A–4C  illustrate alternate forms of audio processing. For example,  FIG. 4A  illustrates vocal sounds due to individuals in the region R speaking to one another. The number and spacings of excursions above a threshold can be counted or accumulated so as to be able to distinguish between normal speaking audio,  FIG. 4A , natural exterior sounds such as thunder,  FIG. 4B  or machine sounds,  FIG. 4C . It will be understood that other forms of processing of incident audio either at the respective detectors, such as detector  10  or at the common processing system  30  come within the spirit and scope of the present invention. 
     As discussed above, processes, for example as in  FIG. 4A , can be used to establish the presence of normal human activity in the region R. In such instances, the sensitivity of the respective detectors can be decreased. In the absence of normal audio, where the region R becomes quiet, the sensitivity of the various detectors can be increased. Similarly, natural external noises such as thunder or normal machine noises in the region R can be filtered so as to not effect the sensitivity setting. 
     Sensitivity adjustments can be fixed for minimum pre-set periods of time so as to remain relatively constant in the presence of occasional intermittent noise. At the end of the time interval, such as 15–20 minutes, sensitivity can again be increased given relative quiet in the region R. Continuous levels of background noise can be filtered out as would be known by those of skill in the art. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.