Abstract:
A device with multiple sensors for detecting multiple alarm conditions coupled to a single control unit provides for monitoring and interrogating air flow through Heating/Ventilation/Air-conditioning (HVAC)-type ducts for changes to ambient conditions such as smoke, heat, gas, and/or relative humidity.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the field of detecting changes to ambient conditions, for example by monitoring and assessing air flow conditions through Heating/Ventilation/Air-conditioning (HVAC)-type ducts and providing alarm indication when ambient conditions are compromised. More particularly, the present invention relates to a device with multiple sensors for detecting multiple alarm conditions coupled to a single control unit. 
   BACKGROUND OF THE INVENTION 
   Ambient condition detectors have been found to be useful in providing an indication of the presence or absence of the respective condition being detected. Smoke, gas, temperature, and relative humidity detectors, for example, have been found useful in providing early warnings of the presence of mechanical malfunction and/or fire. 
   When used in Heating/Ventilation/Air-conditioning (HVAC) duct systems, ambient condition detectors are able to not only signal the presence of alarm conditions anywhere in the building, but also in the machinery of the HVAC ducts themselves. Generally, detectors are placed in either the air-intake or return. When detectors are desired in both intake and return ducts, however, two separate units are installed in each individual duct. This method results in redundant use of circuitry which also adds to the cost of installation and service. 
   Therefore, there continues to be a need for solutions to monitor ambient air conditions in both air supply and air return ducts reducing redundant use of control or monitoring circuitry. It is also desirable to provide an air flow detection system and method that is able to sample the air flow through the detector and compare it to ambient air flow conditions and thereby signal restriction in air flow. 
   SUMMARY OF THE INVENTION 
   The foregoing needs are met, at least in part, by the present invention where, in one aspect, a device is provided for use in ambient condition having multiple sensors coupled to a single control unit. An integrated device for installation, for example, in HVAC ducts for detecting a dangerous condition is provided, comprising a first sensor to determine the presence of a first ambient condition, the first sensor providing a first alarm signal, a second sensor to determine the presence of a second alarm condition, the second sensor providing a second alarm signal, and a control unit, the control unit comprising a processor coupled to the first sensor and the second sensor, the control unit providing a status message indicative of the state of the first alarm signal and second alarm signal. The first detector may be a photoelectric smoke sensor or an ionization smoke sensor in some embodiments. 
   In other embodiments, the detector may have an air flow sensor and a processor to compare said air flow to a low air flow threshold, the processor providing an air flow alarm signal indicative of low air flow status when the air flow status is less than the low air flow threshold. The air flow threshold may be adjustable and/or set to ambient air flow. 
   In yet other embodiments, the detector may have a temperature sensor and a processor to compare the temperature to a high temperature threshold, the processor providing a temperature alarm signal indicative of high temperature when the temperature is greater than the temperature threshold. The temperature threshold may be adjustable and/or set to ambient air flow. 
   In yet still other embodiments, the detector may have a CO 2  sensor and a processor to compare the sensed CO 2  to a high CO 2  threshold, the processor providing a CO 2  alarm signal indicative of high CO 2  when the CO 2  present is greater than the CO 2  threshold. The CO 2  threshold may be adjustable and/or set to ambient air flow. 
   In other embodiments an integrated detection system is provided for installation in HVAC ducts for detecting a dangerous condition, comprising a first sensing means for determining a first ambient condition and for providing a first alarm signal, a second sensing means for determining the presence of a second ambient condition and for providing a second alarm signal, and a control means, the control means comprising a processing means coupled to the first sensing means and the second sensing means for providing a status message indicative of the state of the first alarm signal and second alarm signal. The first detector may be a photoelectric smoke sensor or an ionization smoke sensor in some embodiments. 
   In other embodiments, the detection means may have an air flow sensor and a processing means to compare the air flow to a low air flow threshold and for providing an air flow alarm signal indicative of low air flow status when the air flow status is less than the low air flow threshold. The air flow threshold may be adjustable and/or set to ambient air flow. 
   In yet other embodiments, the detection means may have a temperature sensor and a processor to compare the temperature to a high temperature threshold and for providing a temperature alarm signal indicative of high temperature when the temperature is greater than the temperature threshold. The temperature threshold may be adjustable and/or set to ambient air flow. 
   In yet still other embodiments, the detection means may have a CO 2  sensor and a processing means to compare the sensed CO 2  to a high CO 2  threshold and for providing a CO 2  alarm signal indicative of high CO 2  when the CO 2  present is greater than the CO 2  threshold. The CO 2  threshold may be adjustable and/or set to ambient air flow. 
   There has thus been outlined, rather broadly, several features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
   In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
   As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram of an embodiment of the present invention showing a detector with multiple sensors and a single control unit. 
       FIG. 2  is a block diagram of a power supply and control unit, including an alarm detector and a trouble detector. 
       FIG. 3  is a block diagram of a sensor. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention in some embodiments provides a system and method for providing ambient condition detection having multiple sensors coupled to a single control unit. Preferred embodiments will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. 
   Referring to  FIG. 1 , an integrated detector  1  with sensors  10  and  20  and a single control unit  30  is shown. Additional sensors are integrated as desired with control unit  30 . Many types of ambient condition sensors are known in the art such as smoke, gas, temperature, and relative humidity detectors, and can be used in embodiments of the invention. 
   In embodiments where smoke detectors are used, the sensors are preferably ionization-type or photoelectric. In the embodiment shown in  FIG. 1 , the sensors  10  and  20  relay signals  11  and  21 , respectively, to the control unit  30 . The sensors  10  and  20  will relay smoke alarm signals if they are smoke sensors, and/or heat alarm signals if they are heat sensors and/or gas alarm signals if they are gas sensors. 
   The control unit  30  may comprise both a power supply and an output control as shown in FIG.  2 . However, the power supply may be integral to the control unit  30  or coupled peripherally. In any case, the power supply is powered by power input  41 . The power supply may power the control unit  30  and the sensors  10  and  20 , or alternatively, the sensors  10  and  20  may be independently powered. 
   The control unit  30  may also include a processor to monitor aforementioned signals from the sensors  10  and  20 . The control unit  30  assesses these signals along with other conditions such as power of the power source, and when a trouble condition is present, the control unit  30  sends a status message via a control output  51 . The control output  51  may be transmitted though any of multiple transmission methods, including radio frequency, electronic transmission, and/or fiber optics. The control output  51  may include an audio signal. 
     FIG. 2  shows a greater detail view of control unit  31  and of power supply  40  of the detector embodied in FIG.  1 . The detector  1  is shown comprising a power supply  40  and control unit  31 . Alarm detector  60  and trouble detector  70  are individually coupled to output control  50 . The alarm detector  60 , trouble detector  70 , and output control  50  are parts of control unit  31 . A variety of power inputs  41  to power the power supply  40  are available and can be used, including 120V AC, 220V AC, and 24V AC/DC. 
   The power supply  40  may be equipped to receive the any one or all of the mentioned power inputs. Power output bus  42  may serve to power multiple devices within the detector  1 , including the output control  50 , the detectors  60  and  70 , and individual sensors  10  and  20 , as shown. Power output bus  42  may range from about 12V to about 24V DC, and preferably 18V DC in some embodiments. 
   Each sensor  10  and  20  coupled to the control unit  31  of the detector  1  may individually relay both an alarm signal and a trouble signal. The alarm sensor signal and trouble sensor signal from each of the sensors  10  and  20  are relayed via an alarm bus  12  and a trouble bus  22 , respectively. Information from the alarm bus  12  is synthesized in the alarm detector  60  and the alarm detector signal  61  and is relayed to the output control  50 . Similarly, information from the trouble bus  22  is synthesized in the trouble detector  70  and the trouble detector signal  71  is relayed to the output control  50 . The output control  50  contains a microprocessor to evaluate and interpret the alarm detector signal  61  and the trouble detector signal  71 . Thereupon, the output control  50  relays the appropriate alarm output  52  and trouble output  53 . 
     FIG. 3  shows a detail of sensor unit  10  of a detector  1  of the instant invention. In the embodiment shown, sensor  10  is a smoke sensor, however, as mentioned, sensors of this invention are not limited to smoke sensors. Sensor  10  includes a smoke sensing chamber  80 , a memory  90 , a clock  100 , a microprocessor  110 , status lights  120 , a power supply  130 , and an amplifier  140 . 
   The smoke sensing chamber  80  comprises an infrared (IR) light-emitting diode (LED) transmitter  81  and a photo diode receiver  82 . The transmitter  81  and receiver  82  are generally positioned at 90-degree angles to one another. In the absence of smoke then, the light from transmitter  81  bypasses receiver  82 . When smoke enters the chamber  80 , however, the smoke particles scatter light from transmitter  81  and some amount of light is detected by receiver  82 . The signal  83  from the receiver diode  82  is further amplified by an amplifier  140  en route to the microprocessor  110 . 
   The microprocessor  110  may be calibrated to monitor changes in the signal  83  compared to a transmitter signal  84  that is relayed to IR LED transmitter  81 . A microprocessor clock  100  may be integral or peripheral to microprocessor chip  110 . As with the clock  100 , memory  90  may also be integral or peripheral to the microprocessor chip  110 . The status lights  120  may be LEDs to signal to the operator conditions such as, for example, trouble, alarm, and/or power status of sensor  10 . Likewise, if the sensor is equipped with a filter to remove large particulate matter from the air flow though smoke sensing chamber  80 , then an LED for the dirt status of the filter may also be included on status light display  120 . 
   The status light display  120  may be comprised of a series of LEDs. The LEDs may signal proper function or the indication of an alarm condition when visible light is present. Alternatively, the detector may be designed such that proper function or indication of alarm condition is indicated by the lack of visible light. A combination of light signaling can also be implemented. 
   The microprocessor  110  is supplied power through a power supply  130 . The power source, alarm output, and trouble output, are each coupled to power bus  42 , alarm bus  12 , and trouble bus  22 , respectively. 
   The microprocessors of this invention may be equipped to determine not only the presence or absence of the condition being sensed, but also the status level of the condition being sensed relative to a baseline or threshold value. In other words, a microprocessor of a temperature sensor in some embodiments may be calibrated to not only read the temperature level, but also be able to compare the temperature to a preset threshold. Such a threshold may be adjustable or may be set to ambient temperature. As the temperature of certain buildings may be preset to rise or fall at certain set cycles, so too are microprocessors of the present invention preferably embodied to take the ambient rise and fall in temperature into account when signaling an alarm condition. The same process described above for temperature sensors may also be similarly applied to CO 2 , smoke, and/or relative humidity sensors. 
   In some embodiments, an air flow sensor is also incorporated. Particularly with ambient air condition detectors where filters are placed internally to remove unwanted particulate matter from initiating false alarm signals, air flow can often become compromised when the filters get contaminated. Alternatively, where airflow is deliberately reduced at certain periods of the day, air flow through the sensor can also be reduced. 
   In either event, it is desirable to provide a microprocessor that is able to distinguish restrictions in air flow from air filter contamination from restrictions in air flow from preset reduction in air circulation through out the building. Many devices for detecting and comparing air flow are known and available in the art, including the use of thermistors. 
   The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.