Patent Publication Number: US-2006017577-A1

Title: Systems and methods for the detection of termites

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This Application claims priority to commonly owned U.S. Provisional Patent Application Ser. No. 60/590502; filed Jul. 23, 2004; entitled “The Termite Alarm,” by Kyle Broussard; which is incorporated herein by reference. 
    
    
     BACKGROUND  
      The present invention pertains to systems and methods useful for detecting termites. Certain embodiments of the systems and methods disclosed may be particularly suitable for detecting moisture in a building. Certain embodiments of the systems and methods disclosed may be particularly suitable for detecting the presence of termites in a building.  
      Many buildings are susceptible to damage from moisture. This damage may take the form of cosmetic or structural damage to the building. For example, in some buildings moisture may damage wood or drywall or both. Mold also may colonize a building when excessive moisture is present, which may lead to health problems for the occupants of the building.  
      And moisture in a building may indicate a number of other problems. For example, the presence of moisture in a building may indicate the presence of a plumbing leak or structural leak (e.g., a roof leak). Moisture also may be brought into a building as a result of termite activity and therefore indicate the presence of termites. Termites often transport moisture into a building when feeding on the building&#39;s wood.  
      But moisture, mold, and termites are often difficult to detect because they may occur inside wall cavities, which are, for the most part, impossible to observe absent an intrusion into or removal of a portion of the walls. Accordingly, early identification of moisture in a building may allow for a quick response to remedy any potential problem arising from or indicated by the presence of moisture. And in the case of termites, early identification of where termites have initially invaded the building may serve to prevent a major infestation and the costs associated with repairing any damage to the building after they are exterminated.  
     SUMMARY  
      The present invention pertains to systems and methods useful for detecting termites. Certain embodiments of the systems and methods disclosed may be particularly suitable for detecting moisture in a building. Certain embodiments of the systems and methods disclosed may be particularly suitable for detecting the presence of termites in a building.  
      In one embodiment, the present invention provides a termite detection system, the system comprising: at least one sensor, wherein the sensor generates a signal when there is moisture caused by termite activity; at least one digital processor coupled to the sensor, wherein the digital processor receives the signal from the sensor; and at least one warning device coupled to the digital processor, wherein the warning device is activated when the digital processor receives the signal from the sensor.  
      In another embodiment, the present invention provides method for detecting termites in a building, the method comprising: installing a termite detection system in the building, wherein the termite detection system comprises: at least one sensor, wherein the sensor generates a signal when there is moisture caused by termite activity; at least one digital processor coupled to the sensor, wherein the digital processor receives the signal from the sensor; and at least one warning device coupled to the digital processor, wherein the warning device is activated when the digital processor receives the signal from the sensor; and monitoring the termite detection system until moisture is detected in the building.  
      The features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the embodiments that follow.  
    
    
     DRAWINGS  
      The same numerals in different drawings indicate the same parts of a disclosed system.  
       FIG. 1  shows a cross-sectional schematic of one embodiment of the systems of the present invention placed in a building.  
       FIG. 2  shows a cross-sectional view of a wafer used in some embodiments of the systems of the present invention.  
       FIG. 3  shows a side-view of a plurality of sensors multiplexed according to one embodiment of the present invention.  
       FIG. 4  shows a cross-sectional view of an enclosure housing some of the components of one embodiment of the systems of the present invention. 
    
    
      These drawings form part of the following description and illustrate specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention as defined by the appended claims.  
     DESCRIPTION  
      The present invention pertains to systems and methods useful for detecting termites. Certain embodiments of the systems and methods disclosed may be particularly suitable for detecting moisture in a building. Certain embodiments of the systems and methods disclosed may be particularly suitable for detecting the presence of termites in a building.  
      When placed in the wall cavity of a building, the systems of the present invention may perform a variety of functions. For example, certain embodiments of the systems and methods of the present invention may be useful in detecting moisture. Such systems and methods may be particularly useful, among other things, in termite control efforts, where moisture may indicate the presence of termites. Moisture detection also may be important, for example, in order to alert residents or occupants of buildings about water leaks or mold growth. In general, the systems of the present invention comprise a sensor that is capable of detecting moisture, a digital processor coupled to the sensor, and a warning device coupled to the digital processor.  
      Referring now to  FIG. 1 , a diagram illustrating a termite detection system according to one embodiment of the present invention is shown placed in wall  125 , which may be any wall of any building. Wall  125  includes base plate  160 , stud  170 , top plate  165 , and wall cavity  120 . In some buildings, one or more of base plate  160 , stud  170 , and top plate  165  may be formed from wood.  
      In one embodiment, the termite detection system of the present invention includes sensor  110 , wafer  100 , lead  150 , enclosure  400 , digital processor  410  (not shown in  FIG. 1 ), and warning device  420 . Sensor  110  may be at least partially disposed in wafer  100  (also shown in  FIG. 2 ), among other things, to facilitate moisture detection. Sensor  110  is electrically connected through lead  150  to digital processor  410  (shown in  FIG. 4 ), which is housed in enclosure  400 . Warning device  420  also is electrically connected to digital processor  410 . As used in this description, the term electrically connected refers to any electrical connection capable of completing an electrical circuit, e.g., by using a wire.  
      In certain embodiments, moisture that may accumulate (e.g., in wall cavity  120  or in wafer  100  ) may trigger sensor  110 . Once triggered, an electrical signal passing through lead  150  can be detected by digital processor  410 ; thereby turning on warning device  420  to alert an operator that moisture was detected.  
      Warning device  420  may be any warning device capable of alerting an operator. Suitable warning devices include those that produce a visual signal, such as a light; those that produce an audible signal, such as an intermittent beeper (not shown in  FIG. 1 ); or both. In certain embodiments warning device  420  is an amber colored light, such as the model HT8HFAV3 indication light commercially available from Automation Direct, Cumming, Georgia.  
      Sensor  110  may comprise a sensor capable of detecting the presence of moisture. In certain embodiments, any sensor that operates based on electrical resistance may be suitable for use as sensor  110  in the systems of the present invention. Other sensors suitable for use as sensor  110  include tensiometers, time-domain reflectometers, velocity differentiation domain sensors, capacitance probes, heat dissipation probes, and psychrometers. Example sensors suitable for use in the present invention include the Watermark Soil Moisture Sensor commercially available from Spectrum Technologies, Inc., Planefield, Ill., and the sensor disclosed in U.S. Pat. No. 6,798,220, the relevant disclosure of which is incorporated herein by reference. In one embodiment, sensor  110  is the GB-1 Gypsum Block sensor commercially available from Delmhorst Instruments, Towaco, N.J.  
      Sensor  110  may be placed in any suitable location within or near a building. In some embodiments, sensor  110  may be placed disposed within or near wall cavity  120 . For example, sensor  110  may be disposed substantially within wafer  100 , and wafer  100  with sensor  110  may be placed on base plate  160 . Sensor  110  also may be placed directly in base plate  160  (not shown in  FIG. 1 ) or stud  170  or both. Such placement may be suitable in portions of a building that cannot accommodate placement of wafer  100 .  
      In general, the location of sensor  110  within a building should be known, especially when placed within a wall cavity like wall cavity  120 . Accordingly, a sensor map may be made by labeling a floor plan of the building, or creating a tabular data in a spreadsheet, so as to identify a sensor&#39;s location in the building. In certain embodiments, one or more sensors may be placed around the perimeter of the building, among other things, to detect moisture that may result from termite activity. In other embodiments, one or more sensors may be placed adjacent to or near plumbing, among other things, to detect moisture that may accumulate from a plumbing leak or the presence of termites attracted to the leaking water.  
      Referring now to  FIG. 2 , a cross-sectional side view illustrates sensor  110  disposed within wafer  100  according to one embodiment the present invention. In general, sensor  110  may be partially or fully disposed in any portion of wafer  100 . In certain embodiments, wafer  100  may be of any size or shape suitable for placement in a desired location, for example, between studs that may be present in a building. In certain embodiments, in which wafer  100  may be placed within wall cavity  120  of a building, wafer  100  may have dimensions in the range of about three inches wide and about fourteen inches long.  
      Wafer  100  comprises wood substrate  210  and corrugated substrate  220  assembled in alternating layers. The layers may be formed using the same materials for wood substrate  210  and corrugated substrate  220 , or the layers may be formed using different materials for wood substrate  210  and corrugated substrate  220 . Both wood substrate  210  and corrugated substrate  220  may be formed from a cellulosic material.  
      Wood substrate  210  may be formed from any wood or combination of woods, for example, pine or cork or both. Wood substrate  210  may have a thickness in the range of from about ⅛ inches to about ¾ inches.  
      Corrugated substrate  220  may be formed from a cellulosic material that may have one or more tunnels disposed through or within the cellulosic material. Examples of cellulosic materials suitable for corrugated substrate  220  include one or more of wood, cork, cardboard and paper. In certain embodiments, corrugated substrate  220  has a thickness in the range of from about ⅛ inches to about ¾ inches.  
      In general, wood substrate  210  and corrugated substrate  220  may be joined using any method so long as the layers are in substantial contact. In certain embodiments, the layers may be joined with a glue. One example of a suitable glue is Elmer&#39;s Wood Glue, commercially available from Elmer&#39;s Products, Inc., Columbus, Ohio. In other embodiments, the layers may be joined using a fastener, e.g., a nail, a screw, or metal strap. In one embodiment, wafer  100  comprises 3 layers of a pine wood for wood substrate  200  alternating with 2 layers of a cardboard for corrugated substrate  220 , and the alternating layers are glued together.  
      Referring now to  FIG. 3 , a schematic showing a plurality of sensors multiplexed to form a single circuit according to one embodiment of the present invention. In such configurations, more than one sensor  110  may be electrically connected in a parallel fashion. For example, each of lead  150   a  and  150   b  from sensor  110  may be electrically connected to connection  175   a  and connection  175   b  respectively. A single circuit can then be formed using a plurality of sensors by connecting leads  150   a  and  150   b  to terminal block  430  (shown in  FIG. 4 ) and digital processor  410  (shown in  FIG. 4 ). Any number of sensors may be connected in parallel fashion. For example, in certain embodiments, from about four to about eight sensors are connected in parallel. When sensors are multiplexed, if any one sensor is triggered, the whole circuit activates. When placed in a building, multiplexed sensors may be used to form alarm zones. By using more than one sensor per circuit, the overall costs of the system may be reduced.  
      Referring now to  FIG. 4 , a cross-sectional view illustrates enclosure  400 . Enclosure  400  comprises digital processor  410 , warning device  420 , terminal block  430 , field power supply  440 , AC power supply  450 , and enclosure housing  460 . In some embodiments, digital processor  410  may be any digital processor, such as a programmable logic controller (PLC) a microcontroller, a microprocessor, an application specific integrated circuit, a programmable logic array, and a digital signal processor. Digital processor  410  as shown in  FIG. 4  is a PLC that comprises a power supply module  411 , a central processing unit (CPU) module  412 , an output module  413 , and an input module  414 . In general, digital processor  410  may be built and programmed by a systems integration center so as to turn on warning device  420  when sensor  110  is triggered by moisture. In one embodiment, digital processor  410  is Automation Direct DL240 digital processor with spring-clamp I/O, 12/24 volt DC discreet inputs, 24 volt DC discreet outputs, and an external 12 volt DC power supply for field circuits, commercially available from Automation Direct of Cumming, Ga. Enclosure  460  may be any commercially available instrument enclosure housing. As discussed above warning device  420  may be any type of warning device, or combination of warning devices.  
      Modules  411 - 414  of digital processor  410  are inserted into the backplane (not shown in  FIG. 4 ) of digital processor  410 , which electrically connects the modules. Power supply module  411  converts alternating current from power supply  450  to direct current, which is distributed to modules  412 - 414  through the backplane.  
      CPU module  412  may be programmed with operating commands suitable for the systems of the present invention. In one embodiment, the programming may use a single rung of ladder logic in which all the inputs and outputs are normally-open contacts, and the inputs and outputs are connected. Thus, if sensor  110  detects enough moisture to activate input  415 , the program would energize output  417  and turn on warning device  420 . In some embodiments, CPU module  412  also may be programmed to turn on warning device  420  in case the digital processor diagnostics detect a component failure.  
      Output module  413  is a 24-volt output card that may be electrically connected to warning device  420 ; or, in certain embodiments, to more than one warning device  420  (not shown in  FIG. 4 ). Input module  414  is a 12/24-volt input card that may be capable of accepting more than one input. Input module  414  also may include one or more light emitting diodes (LED), e.g., LED  425 . Each input (e.g., input  415  ) on input module  414  should correspond to a LED (e.g., LED  425  ) so that when the input receives a signal, the corresponding LED is activated. In certain embodiments, module  414  may accept inputs in the range of from about 1 to about 32. For example, module  414  may accept inputs from 16 individual sensors.  
      Lead  150   a  and  150   b  from sensor  110  may be disposed through enclosure  460 . Lead  150   a  should be connected to terminal block  430 ; and lead  150   b  should be connected to input module  414 . Each sensor should have a physical address on the input module  414  that corresponds to a LED. For example, sensor  110  is connected to input module  414  at input  415  so that when sensor  110  is triggered, LED  425  is turned on. This way a triggered sensor&#39;s location in a building can be determined after comparison to a sensor map (described above).  
      AC power supply  450  supplies power to digital processor  410  and sensor  110 . AC power supply  450  is electrically connected to digital processor  410  and to field power supply  440 . Field power supply  440  converts alternating current from power supply  450  and provides 12-volt direct current to terminal block  430 , which should be internally jumpered. As discussed above, one or more sensors may be electrically connected to terminal block  430  and to input module  414 , thus completing an electrical circuit. AC power supply  450  is electrically connected to building&#39;s electrical supply, e.g., 110-volt alternating current. AC power supply  450  should be grounded for safety, e.g., by using the building&#39;s ground.  
      The systems of the present invention may be used in methods of detecting termites in a building. Such methods comprise installing a moisture detection system in a building, wherein the moisture detection system comprises a sensor that generates a signal when there is moisture, a digital processor coupled to the sensor, a warning device coupled to the digital processor; and monitoring the moisture detection system until moisture is detected in the building. In one embodiment of the methods of the present invention, moisture may trigger sensor  110  (shown in  FIG. 1  and  FIG. 4 ). In turn, digital processor  410  (shown in  FIG. 4 ) turns on LED  425  (shown in  FIG. 4 ) and warning device  420  (shown in  FIG. 1  and  FIG. 4 ). The alarm from warning device  420  may be noticed by an operator, who can check LED  425  on input module  414  to determine the sensor triggered.  
      In one application, the systems of the present invention may be used to detect the presence of moisture resulting from a leak, e.g., a plumbing leak. And in certain embodiments, in which the leak is small, the use of wafer  100  may allow earlier moisture detection. By way of explanation, and not of limitation, it is believed that the corrugations of corrugated substrate  220  of wafer  100  can trap moisture to facilitate early detection of moisture by sensor  110 .  
      In another application, the systems of the present invention may be used to detect the presence of moisture that has been introduced into a building by termites. In order to consume wood in a building, termites require moisture. Accordingly, termites may transport moisture (e.g., in the form of mud) into wood they are consuming, especially if the wood is dry. In the case of wafer  100 , when termites start to consume wood substrate  200  or corrugated substrate  220  or both, moisture may be transferred to sensor  110 . By way of explanation, and not of limitation, it is believed that wood substrate  200  may provide a suitable food source for a termite, while the tunnels of corrugated substrate  220 , which resemble natural termite tunnels, allow easier access to wood substrate  200 .  
      To facilitate a better understanding of the present invention, the following examples are given. In no way should these examples be read to limit or to define the scope of the invention.  
     EXAMPLES  
      The Delmhorst GB-1 Gypsum Block sensors are designed to operate on low AC voltage. To test whether the sensors could detect moisture using a DC current 3 test probes were pretreated by soaking and drying in water as directed by the Delmhorst GB-1 Gypsum Block sensor instructions. Next a 13-volt DC excitation voltage was sent to the probes through 100 feet of 24 gage Carol Cable Co. speaker wire (−0.1 volts/50 feet voltage drop) using an AC-to-DC plug-in power adapter. The voltage from the sensors was measured with a Fluke voltmeter. The results are shown in Table 1.  
                           TABLE 1                       Sensor           Wet Sensor Voltage       Number   Supply Voltage   Dry Sensor Voltage   (one drop of water)                                                1   12.9   5.1   11.8       2   12.9   4.3   8.4       3   12.9   3.4   9.4                  
 
      The above test demonstrated, among other things, that the Delmhorst GB-1 Gypsum Block sensors could be used with a DC voltage and still detect moisture.  
      A system that uses 24-volt DC power was thought to be ideal because most digital processors have a built-in 24-volt excitation supply. Testing revealed, however, that a 24-volt excitation voltage resulted in voltage swings that were too great (data not shown). Thus, a 12-volt power supply external to the digital processor was needed for the model system using a digital processor and Delmhorst GB-1 Gypsum Block sensor.  
      Based on the above results a model system using 12-volt direct current and GB-1 Gypsum Block sensors was assembled using the following components: an Automation Direct DL240 with spring-clamp I/O with a 12/24-volt DC input card and a 24-volt DC output card; an Automation Direct amber alarm light; an Automation Direct 12-volt DC power supply; and two GB-1 Gypsum Block sensors (Sensor A and Sensor B). Carol Cable 24-gage paired wire was used to electrically connect the components.  
      The model system was tested in an environment designed to simulate actual working conditions as follows. A hole was cut into the drywall of a house wall and two GB-1 Gypsum Block sensors, sensor A and sensor B, were placed in the wall cavity. The hole was sealed by replacing the cut out drywall piece, and the sensors tested over several days in various outdoor weather conditions. The conditions included morning (high humidity), afternoon (low humidity) and spraying the outside wall with a garden hose and spray nozzle (simulated rainstorm or pressure washing).  
      The 12-volt DC input card that was used in the model system required at or above about a 10-volt excitation to detect a signal from the GB-1 Gypsum Block sensor. So, when power is applied to a dry GB-1 Gypsum Block sensor there must be less than about a 10-volt excitation to avoid a false alarm. A 12-volt DC excitation voltage was applied to Sensor A and Sensor B and the voltage was measured with a Fluke voltmeter. The voltages measured remained below the about 10-volt threshold. Specifically, Sensor A measured 5.6 volts and Sensor B measured 5.7 volts at a relative humidity of 100%. Accordingly, the 12/24-volt DC input card and GB-1 Gypsum Block sensor should not result in a false alarm.  
      To test the ability of Sensor A and Sensor B to reach the 10-volt threshold when exposed to moisture, 12-volt DC current was applied to the probes and the voltage was measured before and after moisture was introduced. Sensor A and Sensor B also were measured 4 hours and 8 hours after 8 drops of water were added to the probes. Table 2 lists the results of the voltage measurements.  
                                   TABLE 2                                           Avg.       Moisture       Initial   Final   Percent   percent       (drops of water)   Probe   volts   volts   increase   increase                                                        2   A   2.5   4.7   85   87       2   B   3.1   5.8   88       4   A   2.5   5.2   107   132       4   B   3.1   7.9   158       6   A   2.5   8.0   219   215       6   B   3.1   9.6   212       8   A   2.5   11.0   337   296       8   B   3.1   10.9   255       8 (4 hours later)   A       11.7   364   320       8 (4 hours later)   B       11.6   275       8 (8 hours later)   A       3.7   48   53       8 (8 hours later)   B       4.9   58                  
 
      The above examples demonstrate, among other things, that the systems and methods of the present invention are capable of detecting moisture.  
      Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims.