Patent Publication Number: US-2003231111-A1

Title: Household marker system and method for detecting household features

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates generally to marker systems, and more specifically, to a marker system for locating various household features.  
       [0003] 2. Background of the Invention  
       [0004] Household features such as gas lines, water supply lines or electrical wiring embedded within walls, floors, or ceilings are difficult to locate after construction has been completed. Drawings are not typically available with this level of detail and may be difficult to find in times when they are needed, such as in a gas leak emergency or during remodeling of the household. Typically, a professional service is needed to locate the pipes or wires, and even with professional assistance, disassembly of a portion of the construction may be necessary.  
       [0005] Leak detectors are available for both water and gas leaks, but they give no exact indication of where the leaky system is installed within the construction. Marker systems are available for locating underground valves and other public systems features by utility companies, but these markers have not been adapted for use within a household.  
       [0006] Another feature of interest associated with a household is the household property line. Surveyors are typically required when the location of a property boundary must be determined. Marker systems have been used to locate archaeological features, but a household property line locator system is not currently available.  
       [0007] Therefore, it would be desirable to provide a system and method for locating household features. It would further be desirable to provide a system and method that may be easily used in the event of an emergency such as a gas leak.  
       SUMMARY OF THE INVENTION  
       [0008] The above objective of locating household features is achieved in a system and method providing detection of previously implanted markers. The system includes one or more markers and a detector. The detector radiates an electromagnetic field at one or more frequencies and the marker resonates at a predetermined frequency and re-radiates energy at that frequency. The detector detects the intensity of the re-radiated field and provides an intensity indication so that the exact location of the marker may be determined by the location of maximum re-radiation from the marker.  
       [0009] The foregoing and other objectives, features, and advantages of the invention will be apparent from the following, more particular, description of the preferred embodiment of the invention, as illustrated in the accompanying drawings.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010]FIG. 1 is a pictorial diagram depicting use of a system in accordance with an embodiment of the present invention to detect the boundaries of a household.  
     [0011]FIG. 2 is a pictorial depicting a buried marker for use in a system in accordance with an embodiment of the present invention.  
     [0012]FIG. 2A is a schematic diagram of a marker circuit.  
     [0013]FIG. 3 is a view showing markers buried around a household in accordance with an embodiment of the present invention.  
     [0014]FIG. 4 is a pictorial diagram depicting use of a system in accordance with a second embodiment of the present invention to detect hidden features in a wall of a household.  
     [0015]FIG. 5 is a detailed pictorial diagram showing an alternative mounting configuration in accordance with an embodiment of the invention.  
     [0016]FIG. 6 is a pictorial diagram depicting the internal structure of a marker in accordance with an embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
     [0017] Referring now to the figures and in particular to FIG. 1, a system in use at a household site in accordance with an embodiment of the present invention is shown. A household property  10  shown with a constructed house  12  and defined by a boundary  14 . Boundary  14  is typically determined by a survey, in which professionals using sophisticated and relatively expensive instruments determine the corners and lines of boundary  14 .  
     [0018] In the method of the present invention, markers  13  are buried at the edges of property  10  and are used to determine the property boundary by an operator  16  using a detector  15 . Detector  15  can be relatively inexpensive to manufacture in large quantities. Using a coil and a frequency generator, the detector emits an electromagnetic field at one or more frequencies. FIG. 3 is a more detailed view of operator  16  using detector  15  to locate buried markers  13 .  
     [0019] Referring now to FIG. 2, marker  13  is illustrated in detail. A plastic housing encloses marker  13  to protect marker  13  from damage due to moisture, soil acidity and fungus, among other environmental effects. Referring to FIG. 6, the electrical details of marker  13  are shown. A ferrite rod  31  is wound with insulated wire  33  to form a coil and a capacitor  32  is wired in parallel. The electrical circuit is shown in FIG. 2A, with a capacitance and inductance in parallel. When detector  15  applies a signal to its internal coil and the coil is brought in proximity with marker  13 , a signal is induced in the parallel marker circuit and a field is re-radiated by ferrite rod  31 . Detector  15  may either stop transmitting and measure the decaying field produced by marker  13  or may measure the effect of the field (enhancement of amplitude at the detector coil) to produce an indication of the intensity of the re-radiated field. The indicator may be a binary LED indicator or a digital or analog meter indicating field strength. Alternatively an audible indicator may be used with a tone or pulse frequency determined by the strength of the re-radiated field. Any or all of the above indications may be used to direct operator  16  in moving detector  15  toward marker  13 . At the maximum intensity of the re-radiated field, the closest location of marker  13  has been found, permitting a homeowner or a service to locate the property boundary  14  without requiring a survey team.  
     [0020] Detector  15  may emit a signal having multiple frequencies, or may emit a single frequency. Generally, the marker circuit (FIG. 2A) should be tuned to resonance at the operating frequency of detector  13 , since the re-radiated field will be much stronger at the resonance frequency. Multiple marker tunings may be used to identify different sets of markers. Detector  15  may also have a switch or other selection mechanism for selecting a single operating frequency, so that a uniquely tuned set of markers may be detected.  
     [0021] Referring now to FIG. 4 a system in accordance with a second embodiment of the invention is depicted. A wall  20  is shown within a house. Wall  20  is cut-away so that various system lines (e.g., gas, water supply, electrical wiring) can be seen. Electrical wiring line  25  is shown and markers  26  are co-located with the line. Natural gas line  23  is shown with markers  24  co-located. Markers  26  and markers  24  may be easily distinguished by different resonant tunings, even if they are set in locations that are very close. Markers  26  and markers  24  are affixed near their corresponding household features (system lines) and can be attached to wall studs  22  or the lines  24 ,  23  themselves by an adhesive, tape or clamp. FIG. 5 depicts a marker  27  affixed to a water supply line  28  using tape. The tape used should have an adhesive lifetime exceeding the structure&#39;s expected lifespan. Affixing a marker to a wall stud may be accomplished by nailing through housing  13 , which is made of a nailable plastic material that will not shatter when affixed to wall stud  24 .  
     [0022] Referring now to FIG. 5, a marker  24  co-located with a gas line  28  and a gas leak detector  27  in accordance with an embodiment of the invention is shown. When gas leak detector emits an audible alarm indicating that a gas leak is present, the location of the detector and gas line may be quickly determined by positioning detector  25  near marker  24  where the audible alarm is heard.  
     [0023] The present invention provides a low-cost system for accomplishing repairs involving hidden household system lines and determining household property boundaries. Both of the above may be accomplished with a single detector using multiple markers.  
     [0024] While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form, and details may be made therein without departing from the spirit and scope of the invention.  
     [0025] For example, there may be other uses for the markers and detectors discussed herein. One such use would be to mark the location of land mines, with the marker detectable by a specialized operating frequency known to the entity placing the mines. This would give such entity the ability to locate and perhaps later remove unused mines from an area that has become secure. The marker could also, in combination with detonation means located on the mine, be used by the placing entity to remote detonate mines from air airplanes, drones, or the like.