Abstract:
A device with a multi-function test feature for assessing or directing multiple sensor functions is provided 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  
         [0001]    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 test features for assessing or directing sensor functions.  
         BACKGROUND OF THE INVENTION  
         [0002]    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 conditions such as, for example, mechanical malfunction and/or fire.  
           [0003]    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, HVAC detectors have special requirements over conventional detectors. For example, HVAC detectors often sample airflow behind dust filters, which are required to prevent dirt or dust related false alarms. When clean, these filters serve to remove undesirable dust particles from activating the alarm, while still allowing a steady rate of air to flow through the detection mechanism. However, dust filters become clogged over time, compromising sensor function and necessitating periodic maintenance of the filter in addition to the operational checks of, for example, the power supply and detector operation.  
           [0004]    Furthermore, HVAC detectors and sensors, particularly in industrial buildings, are often installed in remote locations and thus can be difficult to precisely locate when installed behind walls or within ducts, for example. Access to and disassembly of an installed smoke detector for mere checking the contamination level of a filter or activity of a sensor, for example, is undesirably cumbersome, undesirable, and uneconomical.  
           [0005]    Therefore, there continues to be a need for an apparatus and method to test the functionality of a detector without necessary disassembly of an installed detector. It is also desirable to provide a means to test multiple functional parameters of a sensor with a single test feature that can optionally be actuated without necessary direct access to the detector.  
         SUMMARY OF THE INVENTION  
         [0006]    The foregoing needs are met, at least in part, by the present invention wherein a device is provided with a switch that can perform multiple testing functions. The multi-test switch may be employed alone in an individual sensor of a ambient condition detector, or alone in a control unit coupled to multiple sensors, or in combination, with a respective switch being present on both the individual sensors and the control unit.  
           [0007]    In one embodiment, a detector for detecting a condition is provided, comprising a first sensor that determines the presence of a first condition and provides a first alarm signal, a switch with a first engaged position for activating a first activity and a second engaged position for activating a second activity; and a control unit comprising a processor coupled to the sensor that provides a status message indicative of the state of the first alarm signal. In some embodiments, the detector may also comprise a second sensor to determine the presence of a second condition and provide a second alarm signal. The first sensor may be a photoelectric smoke sensor or an ionization-type smoke sensor. The first activity engaged by the switch may be an alarm test. In those embodiments wherein the sensor comprises an air filter, a filter test may also be engaged by the multi-test switch.  
           [0008]    In other embodiments, the detector may comprise an air flow sensor and a processor to compare the 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.  
           [0009]    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.  
           [0010]    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.  
           [0011]    In yet still other embodiments, the detection device may comprise a second smoke sensor or a relative humidity sensor.  
           [0012]    In other embodiments, a device is provided for detecting a condition, comprising a sensor that determines the presence of a condition and provides an alarm signal; a switch with a first engaged position for activating a first activity and a second engaged position for activating a second activity; and a processor for providing a status message indicative of the state of the alarm signal.  
           [0013]    In other embodiments a device is provided for detecting a dangerous condition, comprising a first sensing means for determining a first ambient condition and for providing a first alarm signal, a switching means with a first engaged position for activating a first activity and a second engaged position for activating a second activity; and control means comprising a processing means coupled to the sensing means for providing a status message indicative of the state of the first alarm signal. The sensing means may be a photoelectric smoke sensor or an ionization smoke sensor in some embodiments.  
           [0014]    There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.  
           [0015]    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 embodiments in addition to those described 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.  
           [0016]    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  
       [0017]    [0017]FIG. 1 is a block diagram of a power supply and control unit, including an alarm detector and a trouble detector.  
         [0018]    [0018]FIG. 2 is a block diagram of a sensor.  
         [0019]    [0019]FIG. 3 is a flow chart of the logic operation of functions the detector will perform in one embodiment.  
         [0020]    [0020]FIG. 4 is a flow chart of the logic operation of the test for filter contamination in one embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0021]    While this invention is susceptible of embodiment in many different forms, there are shown in the drawing figures and will be described herein in detail specific embodiments thereof 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 embodiments illustrated.  
         [0022]    The multi-test switch feature described herein can be used with a single sensor unit, or on a control unit of a detection system that is coupled to multiple individual sensors. Alternatively, multi-test switches of the present invention may also be installed in both the individual sensors and a control unit in combination. Switches of the present invention need not be limited to any particular sensor or detector. In fact, many types of ambient condition sensors are known in the art such as, for example, 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. Switches described herein can be adapted for all known detectors in the art from the teachings described herein.  
         [0023]    [0023]FIG. 1 illustrates one embodiment of the instant invention wherein the ambient condition detector  1  comprises multiple sensors  10  and  20  that are operationally coupled to a control unit  30 . Additional sensors may be integrated as desired with control unit  30 . The control unit  30  may comprise both a power supply  40  and an output control  50  as shown. Alternatively, in other embodiments, the power supply  40  may be coupled to the control unit  30  peripherally (not shown). In any case, the power supply  40  is powered by a power input  41 . 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, and the power supply  40  may be equipped to receive the any one or all of the mentioned power inputs. The power supply  40  may power the control unit  30  and the sensors  10  and  20 , or alternatively, the sensors  10  and  20  may be independently powered. The power supply  40  transmits power through the power output bus  42 . The 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 the individual sensors  10  and  20 , as is shown. The power output bus  42  may range from 12V to 24V DC, and preferably is 18V DC in some embodiments.  
         [0024]    The power output bus  42  is coupled to the individual sensors  10  and  20  by means of a switch  80 . When in the “on” position, the switch  80  directs power from the power supply  40  to the sensors  10  and  20  via power output bus  42 . When the switch  80  is activated to the “off” position, however, transmission of power is interrupted to the sensors  10  and  20 . In the embodiment shown, activation of the switch  80  only terminates power to the sensors  10  and  20 , but not to the other devices, the output control  50 , the alarm detector  60 , and the trouble detector  70 . It will be understood from the description herein, however, that the switch  80  may be incorporated in other locations to operationally supply or interrupt power to any one or all of the devices.  
         [0025]    Many known switching means are known to those skilled in the art and may be employed for the switch  80 . Preferably, in some embodiments, the switch  80  will be a multi-test switch. That is, one switch will embody multiple functions. As will be detailed below, switches of this invention will preferably have multiple engagable positions such that in one engaged position, the switch may signal one function or test, whereas in other engaged positions, the switch may signal a second function or test. In other embodiments, the switch may embody yet another engaged position so to signal yet a third function or test. In some embodiments, the switch may preferably be a single button, whereby multiple engaged positions may be indicated by the length of time the button remains depressed.  
         [0026]    Turning to the coupling of the sensors  10  and  20  to the control unit  30  now, each sensor  10  and  20  is coupled to the control unit  30  of the detector  1  and 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  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 .  
         [0027]    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 the outputs  51  and  52 . The outputs  51  and  52  may be transmitted though any of multiple transmission methods, including radio frequency, electronic transmission, and/or fiber optics, and may optionally include an audio signal.  
         [0028]    In the embodiment shown in FIG. 1, the alarm detector  60  and the trouble detector  70  are individually coupled to the output control  50 . As shown, the alarm detector  60  and the trouble detector  70 , along with the switch  80  and the output control  50  are all installed as part of control unit  30 . However, each of the aforementioned devices may be installed peripheral to the control unit  30 , and not be encompassed in a single unit therein.  
         [0029]    [0029]FIG. 2 shows a detail of the sensor unit  10  of the detector  1  in one embodiment of the instant invention. As mentioned above, one of ordinary skill in the art will appreciate from the teachings herein that the sensor may also be a stand-alone unit without the need for a separate control unit as shown in FIG. 2. Such embodiments are within the scope of the instant invention. Also in the embodiment shown, the sensor  10  is a smoke sensor; however, as mentioned, the sensors of this invention are not limited to smoke sensors.  
         [0030]    The sensor  10  includes a memory  90 , a clock  100 , a microprocessor  110 , status lights  120 , a power supply  130 , an amplifier  140 , and a smoke sensing chamber  150 . The smoke sensing chamber  150  comprises an infrared (IR) light-emitting diode (LED) transmitter  151  and a photo diode receiver  152 . The transmitter  151  and receiver  152  are generally positioned at 90-degree angles to one another. In the absence of smoke then, the light from transmitter  151  bypasses receiver  152 . When smoke enters the chamber  150 , however, the smoke particles scatter light from transmitter  151  and some amount of light is detected by receiver  152 . The signal  153  from the receiver diode  152  is further amplified by the amplifier  140  en route to the microprocessor  110 .  
         [0031]    The microprocessor  110  may be calibrated to monitor changes in the signal  153  compared to a transmitter signal  154  that is relayed to IR LED transmitter  151 . The 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 the sensor  10 . In some embodiments, the status lights may be replaced by or combined with an audio annunciation. Likewise, if the sensor  10  is equipped with a filter to remove large particulate matter from the air flow though the smoke sensing chamber  80 , then an LED for the dirt level of the filter may also be included on the status light display  120 .  
         [0032]    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. In some preferred embodiments, a single light may be used to display multiple conditions. As will be explained in more detail below, for example, a single flash of the light may indicate a first status, a double flash of light may indicate a second status, so on and so forth. The same concept may be applied to audio annunciation.  
         [0033]    The power source, alarm output, and trouble output, are each coupled to the power bus  42 , the alarm bus  12 , and the trouble bus  22 , respectively, and operably coupled to the microprocessor  110 . The microprocessor  110  is supplied power through a power supply  130  and may be equipped with a power monitor input  161 . In the event of inadvertent power failure, the power buffer  160  buffers the sudden drop in power or alternatively, buffers the sudden rise in power when power is once restored.  
         [0034]    In some embodiments, the multiple testing features of the detectors of the instant invention are activated though intermittent cessation of power to the microprocessor. Such deliberate interruption of power by the operator is also buffered by the power buffer  160 . The microprocessor  110  then “reads” the interruption in power from the power input  161  and activates the appropriate test feature and/or response.  
         [0035]    In some embodiments, the sensors and detectors of the instant invention may be equipped with a reed switch  170 . In this embodiment, instead of intermittently dropping the voltage from the outside of a cover of the detector or sensor, the reed switch  170  is turned on when a magnet is brought into proximity by an operator. Upon this turning-on of the reed switch  170 , a test signal  171  is relayed to the microprocessor  110 .  
         [0036]    Here, in the above-described embodiment, in order to keep the reed switch  170  on continuously during test, the inspector must continuously hold a magnet in close proximity to the reed switch  170 . Where multiple tests may be signaled though a single reed switch  170  in some embodiments, different tests may be signaled by the duration of the reed switch  170  in the “on” position. That is, the length of time the magnet is placed in proximity to the reed switch  170  will indicate the time of engagement which may also indicate the type of test desired by the operator.  
         [0037]    In addition, in the present invention, instead of the reed switch  170  and the magnet, an optical switch, such as an LED, or a wireless switch, such as infrared rays, or radio waves may be used as the test switch. Still alternatively, a test command, such as by intermittent changes in voltage, may be transmitted from a control panel to start test thereby effecting a remote test.  
         [0038]    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.  
         [0039]    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.  
         [0040]    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.  
         [0041]    One example of how a single switch may be used to activate multiple functions will now be described. Many permutations of the example given are possible and will be understood to one of ordinary skill in the art, and all such permutations are within the scope of the invention. In one embodiment, detectors of the instant invention are equipped with a multi-test button on both the control unit and on the individual sensors. Under conditions where an alarm has been activated, the button serves to reset the detector by virtue of dropping power to the sensors. The microprocessors of the sensors detect a temporary drop in voltage and shut down the alarm. The individual sensors  10  and  20  then sense whether or not the alarm condition is still present, and then reactivate the alarm or remain reset accordingly.  
         [0042]    When no alarm condition is present and therefore no alarm has been activated, the same multi-test button, that functions to reset the sensors in an alarm condition, may serve as an alarm test or a test for filter contamination (“dirt test”) depending on the duration the button remains depressed on the control unit or sensor. FIG. 3 shows a flow chart of the logic operation of functions the detector will perform. When the button is depressed the mechanical switch is “active”. “Active” in this embodiment refers to the period of time power to the sensors is interrupted. The microprocessor  110  then assesses the length of time the switch is active. If the switch is active for less than 1 second, then no test is initiated. However, if the switch is active for 1 to 4 seconds, then the dirt test is initiated. Alternatively, if the switch is active for greater than 4 seconds, an alarm test is initiated. Upon completion of the dirt test or the alarm test, the mechanical switch is automatically reset to the inactive position.  
         [0043]    In the embodiment described, a reed switch may also be incorporated on the individual sensors. The reed switch operationally functions similarly to the button switch on the control unit. For example, depressing the button switch is analogous to bringing a magnet into proximity to the reed switch. Moreover, depression of the button switch for 3 seconds is equivalent to holding a magnet to the reed switch for 3 seconds. Therefore, the magnet and reed switch combination can be operable in a manner similar to the button switch described above.  
         [0044]    [0044]FIG. 4 shows a flow chart of the logic operation for the filter contamination (“dirt test”) in one embodiment of the present invention. Once the dirt test has been activated by one of several means mentioned above (e.g., activation of the reed switch  160 ), the microprocessor  110  first determines the dirt level by comparing the dirt present on the filter with that present when first installed. Once a percentage of dirtiness is calculated, the processor then computes which one of five dirt levels is present. As outlined in FIG. 3. dirt level 1 is indicative of 0%-25% contamination, dirt level 2 is indicative of 26%-50% contamination, dirt level 3 is indicative of 51%-75% contamination, dirt level 4 is indicative of 76%-99% contamination, and dirt level 5 is indicative of complete (100%) contamination. Depending on the dirt level, the microprocessor  110  then transmits the appropriate signal to an LED display which flashes once, twice, thrice, four times, or continuously to indicate dirt level 1, 2, 3, 4, or 5, respectively.  
         [0045]    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.