Patent Publication Number: US-11665321-B2

Title: Pipe inspection system with replaceable cable storage drum

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND PATENTS 
     This application is related to U.S. Utility patent application Ser. No. 12/399,859, filed Mar. 6, 2009, entitled PIPE INSPECTION SYSTEM WITH SELECTIVE IMAGE CAPTURE. It is also related to U.S. Utility patent application Ser. No. 12/371,540, filed on Feb. 13, 2009, entitled HIGH-PERFORMANCE PUSH CABLE and to U.S. Utility Pat. No. 5,808,239 granted Sep. 15, 1998, entitled VIDEO PUSH CABLE. The entire disclosures of the aforementioned applications and patent are hereby incorporated by reference. This application is a continuation of and claims priority to U.S. Utility patent application Ser. No. 12/704,808, filed Feb. 12, 2010, entitled PIPE INSPECTION SYSTEM WITH REPLACEABLE CABLE STORAGE DRUM, which claims priority under 35 U.S.C. § 119(e) to Provisional U.S. Patent Application Ser. No. 61/152,662 filed Feb. 13, 2009, entitled HIGH-PERFORMANCE PIPE INSPECTION SYSTEM, and to Provisional U.S. Patent Application Ser. No. 61/152,947, filed Feb. 16, 2009, entitled PIPE INSPECTION SYSTEM WITH REPLACEABLE CABLE STORAGE DRUM. 
    
    
     BACKGROUND 
     Field of the Invention 
     This invention relates generally to pipe inspection systems employing a camera head connected to the end of a push-cable payed out from a rotatable cable drum. 
     Description of the Related Art 
     There are many situations where it is desirable to internally inspect long lengths of pipe that are already in place, either underground, in a building, or underwater. For example, sewer and drain pipes frequently must be internally inspected to diagnose any existing problems and to determine if there are any breaks causing leakage or obstructions impairing the free flow of waste. It is also important to internally inspect steam pipes, heat exchanger pipes, water pipes, gas pipes, electrical conduits, and fiber optic conduits for similar reasons. Frequently, pipes that are to be internally inspected have an internal diameter of six inches or less, and these pipes may make sharp turns. It is sometimes necessary to internally inspect several hundred feet of pipe. 
     Conventional video pipe inspection systems include a video camera head that is forced down the pipe to display the pipe interior on a video display. The inspection is commonly recorded using a video recorder (VCR) or digital video disk (DVD). Conventional video pipe inspection systems have included a semi-rigid push-cable that provides an electromechanical connection between the camera head that encloses and protects the video camera and a rotatable push reel or cable storage drum that is used to pay out push-cable and force the camera head down the pipe. Examples of suitable video push-cables are disclosed in U.S. Pat. No. 5,457,288, entitled DUAL PUSH-CABLE FOR PIPE INSPECTION, issued Oct. 10, 1995, and U.S. Pat. No. 5,808,239, entitled VIDEO PUSH-CABLE, issued Sep. 15, 1998. The video camera head design and the manner in which it is connected to the push-cable are important to the performance and reliability of a video pipe inspection system. 
     Conventional pipe inspection systems use a semi-rigid push-cable to move the camera head down a length of pipe. The push-cable must be resilient and have enough flexibility to enable the camera head to negotiate turns. The types of push-cables used in conventional pipe inspection systems limit the turn radius through which the camera may pass, making it extremely difficult, for example, to inspect the interior of a toilet drain or a sink drain due to the tight turns of their piping. 
     A conventional video pipe inspection system includes a reel or drum for storage of the coils of the push-cable. The reel or drum is typically supported on a frame for rotation about a horizontal or a vertical axis for paying out the push-cable and for rewinding the push-cable for storage. A slip-ring assembly is typically included in the hub and/or axle of the reel or drum to continue electrical connections between the end of the push-cable and external circuits that power the camera head and receive video signals therefrom. Existing systems tend to be heavy and unwieldy in field operations, suffering in portability in order to store hundreds of feet of semi-rigid push-cable around the reel or inside the drum. Traditional storage drums are difficult to remove from the frame of the system, difficult to clean, and can be used only with a single proprietary inspection camera and connection system for which they are designed. Additionally, because of the design of their push-cable and the size of camera heads commonly used, conventional pipe inspection systems cannot negotiate extremely small-bore passages and extremely tight turns. 
     SUMMARY OF THE INVENTION 
     The present invention provides a pipe inspection system including a cable storage drum and a housing configured to removably receive and rotatably support the cable storage drum. A push-cable with a plurality of conductors is stored in the cable storage drum. A camera head is connected to a distal end of the push-cable. A slip-ring assembly has first and second mating portions that when mated provide conductive paths between the plurality of conductors at a proximal end of the push-capable and a display device. The first portion of the slip-ring assembly is mounted on the housing and the second portion of the slip-ring assembly is mounted on the removable cable storage drum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagrammatic illustration of an exemplary embodiment of the pipe inspection system of the present invention as deployed in use. 
         FIG.  2 A  is an isometric front view of the exterior of the pipe inspection system in its stowed configuration illustrating external components. 
         FIG.  2 B  is an isometric rear view similar to  FIG.  2 A . 
         FIG.  2 C  is a view similar to  FIG.  2 A  with the front outer casing removed. 
         FIG.  2 D  is a view similar to  FIG.  2 B  with the rear outer casing removed. 
         FIG.  2 E  is an isometric front view illustrating the external clam-shell case in an open configuration revealing the removable cable storage drum. 
         FIG.  3 A  is an enlarged exploded isometric view of the slip-ring assembly of the system of  FIG.  1    taken from the rear side. 
         FIG.  3 B  is a view similar to  FIG.  3 A  from the front side. 
         FIG.  3 C  is an enlarged vertical sectional view of the slip-ring assembly illustrated in  FIGS.  3 A and  3 B . 
         FIG.  4 A  is an enlarged vertical sectional view of the pipe inspection system of  FIG.  1    taken through the rotational axis of the cable storage drum. The hand-held display and image capture device is not illustrated in this view. 
         FIG.  4 B  is a still further enlarged portion of  FIG.  4 A  illustrating the relationship between the slip-ring assembly and the bearing surfaces of the clam-shell housing that support the cable storage drum. 
         FIG.  4 C  is a view similar to  FIG.  4 B  with a portion of the slip-ring assembly removed to illustrate the details of the push-cable connection to the slip-ring assembly. 
         FIG.  4 D  is a view similar to  FIG.  4 B  rotated to illustrate further details of the hub-cone and slip-ring connections. 
         FIG.  5 A  is an isometric front view illustrating the clam-shell housing opened and the cable storage drum moved away from the clam-shell housing. 
         FIG.  5 B  is an isometric rear view similar to  FIG.  5 A . 
         FIG.  6 A  is an enlarged vertical section view of the imaging device interface connector of the pipe inspection system of  FIG.  1   . 
         FIG.  6 B  is a view similar to  FIG.  6 A  rotated ninety degrees. 
         FIG.  7    is an isometric view of an embodiment of the pipe inspection system of the present invention illustrating the removable system cable and interface connector for use with a Perceptron® hand-held imaging device. 
         FIG.  8 A  is an isometric view of an alternate embodiment of the pipe inspection system of the present invention illustrating the removable system cable and interface connector for use with a SeeSnake® display device. 
         FIG.  8 B  is an isometric view of the pipe inspection system of  FIG.  8 A  oriented for horizontal use with incorporated built-in feet. 
         FIG.  9 A  illustrates a central control keypad in the hub structure utilized in an alternate embodiment. 
         FIG.  9 B  is a sectional view of the hub and drum in the embodiment shown in  FIG.  9 A . 
         FIG.  10    is an exploded view of a system including the keypad and hub structure of  FIG.  9 A . 
         FIG.  11 A  is an exploded view of an alternate embodiment of the slip-ring module with external pockets for the sensing magnets. 
         FIG.  11 B  illustrates the module of  FIG.  11 A  from the opposite side perspective. 
         FIG.  11 C  is a section view of the module of  FIGS.  11 A and  11 B . 
         FIG.  12    illustrates an alternate embodiment that uses a replaceable drum carrying a sonde instead of a camera assembly at the distal end of the cable. 
         FIGS.  13    A and  13 B are views illustrating a sonde construction integrated into the camera head of an inspection system. 
     
    
    
     Unless the parts are electrical connections or fasteners, the parts illustrated in the drawings are generally made of molded plastic. Throughout the drawing figures, like reference numerals refer to like parts. 
     DETAILED DESCRIPTION 
     The present invention provides an improved pipe inspection system that is lower in weight and more easily portable. It includes a removable and readily replaceable push-cable storage drum that rapidly allows the system to utilize different pipe image cameras that utilize different types of push-cables. The present invention is advantageously utilized with different small hand-held display and image capture devices by the simple expedient of swapping the removable system connection cable for one compatible with a different device. 
     The present invention also provides a novel cable storage drum which is readily removable and replaceable by simply opening two latches on a clam-shell case. As a result, the drum may be rapidly replaced with a drum holding a longer cable, a more flexible cable, or a different camera, or a sonde-only cable system. A separable slip-ring assembly, attached to a removable system cable from a display device, connects the removable push-cable and storage drum with the monitoring electronics. 
     Referring to  FIG.  1   , a pipe inspection system  100  comprises a hand-held display and image capture device  122 , a clam-shell housing including a front outer casing  102  with snap-on molded supporting feet  108 , and removable system connection cable  118  relaying camera information from flexible resilient push-cable  103  to the display and image capture device  122 . A camera assembly  105  and a protective stainless steel coil spring assembly  111  are attached to a distal end of the push-cable  103 . Images generated by the camera assembly  105  within a pipe  107  are electronically translated into electrical impulses transmitted along conductors embedded in the push-cable  103  and transferred through a slip-ring assembly to the system connection cable  118  and then to the display and image capture device  122 . Camera control signals may be transmitted in the reverse direction to the camera assembly  105 . In the embodiment of  FIG.  1    the pipe inspection images are monitored with the commercially available Perceptron® Micro-Explorer hand-held display and image capture device  122 . Other display devices may be used. The push-cable  103  is resilient and flexible and may be of the type illustrated in U.S. Pat. No. 5,939,679, entitled VIDEO PUSH-CABLE, granted Aug. 17, 1999, the disclosure of which is hereby incorporated by reference. For applications with smaller pipe diameters and short camera head insertions, the push-cable  103  may be of the type disclosed in U.S. patent application Ser. No. 12/371,540, now U.S. Pat. No. 8,289,385, entitled PUSH-CABLE FOR PIPE INSPECTION SYSTEM, filed Feb. 13, 2009, or a similar type. The entire disclosure of said application is hereby incorporated by reference. 
     In  FIG.  2 A , the hand-held display and image capture device  122  is seated in a dock handle  110  which is a single molded part. The dock handle  110  serves as a carrying and lifting handle for the overall system as well as a docking station for the hand-held display and image capture device  122 . The dock handle  110  includes a cradle and snap-in mounting features (not visible) for releasably securing the hand-held display and image capture device  122 . A system interface plug  220  removably connected to the system connection cable  118  is used to connect the display and image capture device  122  to the system connection cable  118  ( FIG.  1   ). The front outer casing  102  is oriented toward the viewer in  FIG.  2 A . A symmetrical, identically formed rear outer casing  104  is partially visible on the left side of  FIG.  2 A . The front and rear outer casings  102  and  104  are preferably molded of plastic and are releasably joined by integrally molded cooperating hinges ( 202 ,  FIG.  2 C ) into a clam-shell case which can be latched into a closed configuration by sliding a pair of latches  106  ( FIGS.  2 A and  2 B ). Below the display and image capture device  122  and dock handle  110  two horizontally extending cord-wrap arms  112  and  114  with retainer end flanges are provided so that the system connection cable  118  ( FIG.  1   ) may be wrapped around the same for convenient storage. 
     The front and rear outer casings  102  and  104  include snap-on molded feet  108 . In  FIG.  2 A  one end of a hub cone  124  is seen in the center of an annular cable storage drum assembly  206  ( FIG.  2 C ) that is encased by the two outer casings  102  and  104 . The visible end of the hub cone  124  is formed with a rigid central diametrically extending grip  125  for rotating the cable storage drum assembly  206  ( FIG.  2 C ) by a few degrees to incrementally advance the camera assembly  105  ( FIG.  1   ) down the pipe  107  or tighten the cable coils within the drum. Normally the push-cable  103  is manually pushed or pulled to rotate the cable storage drum assembly  206  and rapidly advance or withdraw the camera assembly  105 . The front outer casing  102  has a molded plastic cable guide  126 , attached by six screws, to guide the push-cable  103  as the cable storage drum assembly  206  is rotated to pay out or re-wind the push-cable  103 . 
     A slip-ring cover  120  ( FIG.  2 B ) provides an entry for the proximal end of the system connection cable  118  for connection to a slip-ring assembly  300  ( FIGS.  3 A and  3 B ). The distal end of the system connection cable  118  is removably coupled to the display and image capture device  122  via the system interface plug  220 , which is not mated in  FIG.  2 B . The slip-ring cover  120  has two recessed grips  121  molded into its surface which are used to remove the slip-ring assembly  300 . The slip-ring cover  120  and the attached slip-ring assembly  300  are unlocked by rotating the slip-ring cover  120  counter-clockwise, freeing a portion of the slip-ring assembly  300  by releasing three locking keys frictionally secured to the rear outer casing  104 . A cover plate  128  and cable grip  129  cover the opening in rear outer casing  104  which corresponds to the push-cable guide  126  and its opening in the front outer casing  102  ( FIG.  2 A ). 
     In  FIG.  2 C , the pipe inspection system  100  is illustrated with the front outer casing  102  removed to expose cable storage drum assembly  206  seated within the rear outer casing  104 . The molded hinge  202  and hinge pin  216  which join the casing halves into a clam-shell form can be seen at the bottom of rear outer casing  104  forward of foot  108 . One of the latches  106  is illustrated in  FIG.  2 C  in its upward, or OPEN position. The push-cable  103  is stored in a coil of multiple turns within the cable storage drum assembly  206  which, with the attached hub cone  124 , rotates on molded circular bearing surfaces integral to rear outer casing  104  and front outer casing  102  ( FIG.  2 A ). A user may manually grip the push-cable  103  in the vicinity of the cable guide  126  and push it down the pipe  107  ( FIG.  1   ), which pulls the push-cable  103  out of the cable guide  126 , at the same time rotating the cable storage drum assembly  206 . In  FIG.  2 C  a hub shield  214  is partially visible that is attached along the lower outer surface of hub cone  124 . The hub shield  214  serves to protect and secure the electrical connections between push-cable  103  and hub cone  124  as will be hereinafter described. Cable storage clip  117  serves to retain the system connection cable as needed. 
     In  FIG.  2 D , the rear outer casing  104  of pipe inspection system  100  has been removed revealing the cable storage drum assembly  206 . Visible in this view are the dock handle  110 , case latch  106 , cord-wrap arms  112  and  114 , with an attached cable storage clip  116  for retaining the stored system connection cable  118  ( FIG.  1   ). Molded feet  113  and  115  are seen attached to the projecting arms of the cord-wrap arms  112  and  114 , which serve to support the pipe inspection system  100  in a horizontal orientation in use if desired, as illustrated in  FIG.  8 B . 
     Display and image capture device input connector  504  on the display and image capture device  122  mates to the system interface plug  220  ( FIG.  2 B ) connecting it to system connection cable  118 . Within the hub cone  124 , a hub PCB mount  406  supports a hub PCB  402  on which annular electrical contact rings  404  are etched. 
     Referring to  FIG.  2 E , the front and rear casings  102  and  104  provide a clam-shell housing that is opened at the hinge molding  202  ( FIG.  2 C ) by the opening of the two latches  106 . The hand-held display and image capture device  122  is removably seated in the dock handle  110  located above the cord-wrap arms  112  and  114 , with system interface plug  220  partially obscured, and not mated to the display and image capture device  122 . The curvature in the sides of dock handle  110  is designed to provide a snap fit when the display and image capture device  122  is seated in the dock handle  110 . The lower portion of the dock handle  110  is configured with sufficient strength and rigidity to serve as a lifting handle for the entire pipe inspection system  100 . Opening the clam-shell housing, by first moving latches  106  on the left and right of pipe inspection system  100  upwardly, leaves the cable storage drum assembly  206  accessible for easy removal simply by lifting it out of the rear outer casing  104 , such as for cleaning, repair or replacement of push-cable  103 , camera assembly  105  and/or coil spring assembly  111 , or replacing it with a different drum assembly. Cable storage clip  117  serves to retain the system connection cable as needed. 
     Referring now to  FIG.  3 A , the system connection cable  118  leading from the hand-held display and image capture device  122  ( FIG.  1   ) enters the slip-ring cover  120  through an opening between the two recessed grips  121  and passes through a grommet  119 . The system connection cable  118  is secured onto slip-ring cover  120  by, for example, a two-eared clamp  313  ( FIG.  3 B ), and its conducting leads are connected electrically to a female connector  308  ( FIG.  3 B ). The female connector  308  ( FIG.  3 B ) mates with a three-pin IDC male connector  311  mounted on the back side of a fixed PCB  210 . Three annular contact rings  306  ( FIG.  3 B ) are formed on the front side of the PCB  210 . Six contact pins  226  of a graphite-silver compound are biased by corresponding gold-plated springs  227 . Springs  227  contact against the three annular contact rings  306  ( FIG.  3 B ), two pins on each of the contact rings  306 . The use of dual spring-loaded contact pins  226  for each of the annular contact rings  306  reduces contact noise in the transmission of electrical signals. The contact pins  226  and springs  227  are mounted in corresponding cylindrical sleeves  229  molded in a central wall portion of a cylindrical slip-ring housing  208 , and the contact pins  226  and springs  227  are retained in sleeves  229  by a rubber contact seal  302  and a retainer  310 . The seal  302  is designed so that it seals the contact pins  226  in a water-tight fashion as they pass through the seal  302 . The slip-ring housing  208  is formed with peripheral locking keys such as  209  which are engaged by mating features on the rear outer casing  104 . The slip-ring assembly  300  can be manually inserted and twist-locked into the center of the rear outer casing  104  ( FIG.  2 B ). The outer casings  102  and  104  of the clam-shell housing can then be latched together. The contact pins  226  are then held by the force of the springs  227  in electrical contact with a plurality of contact rings  404  ( FIG.  2 D ) on a hub PCB  402  within the cable storage drum assembly  206  providing conductive paths between the push-cable  103  and the system connection cable  118 . On the inner side of slip-ring housing  208 , pockets are molded which retain magnets such as  407 . 
     Referring to  FIG.  3 B , the slip-ring housing  208  has sleeves in its central wall for the six contact pins  226  ( FIG.  3 A ) which are fit tightly through aligned apertures in the slip-ring contact seal  302  held by the seal retainer  310 . The annular contact rings  306  may be etched into the copper cladding of the PCB  210  and are fixed relative to the contact pins  226  and do not rotate. Four screws  320  hold the slip-ring housing  208  and slip-ring cover  120  together. Three screws  322  pass through the perimeter of the seal retainer  310  attaching retainer  310  and seal  302  within a cylindrical shield ring  326  of the slip-ring housing  208  over the sleeves  229 . The shield ring  326  is a molded section of the slip-ring housing  208  specifically designed to provide a protective recess for the protruding pins  226  seated in springs  227  and passing through the rubber seal  302  from the sleeves  229 . Three screws  324  are attached from the back side of the PCB  210  to hold the PCB  210  onto the slip-ring housing  208 . This compresses the springs  227 . The slip-ring assembly  300  including the system connection cable  118  is entirely removable. 
     Turning now to  FIG.  3 C , the system connection cable  118  passes through the rubber grommet  119  as it enters the slip-ring cover  120 . A plurality of leads or conductors inside the system connection cable  118  are connected to the female connector  308 , which mates with the male connector  311  mounted on the PCB  210 . The system connection cable  118  is secured to the slip-ring cover  120  by the clamp  313  which is in turn secured by two screws. The connecting surfaces of slip-ring cover  120  and slip-ring housing  208  deform and secure a seal  315 . The screws  324  hold the PCB  210  onto the slip-ring housing  208 . The springs  227  and the contact pins  226  are restrained by the rubber seal  302 , and the retainer  310  is held in place by the screws  322 . The shield ring  326  is formed so that the protruding contact pins  226  are well below the outer edge of the slip-ring housing  208 , providing the contact pins  226  with protection from incidental impact or abrasion in use. 
     In  FIG.  4 A  a sectional view of pipe inspection system  100  is seen from above with system connection cable  118  and slip-ring assembly  300  on the left, held in place on rear outer casing  104 . The four molded feet  108  support the outer casings  102  and  104 . The cable storage drum assembly  206  is illustrated within the casings. The push-cable  103  is seen entering cable storage drum assembly  206 , in cross-section. The central alignment of the hub cone  124  and the slip-ring assembly  300  is clearly illustrated in  FIG.  4 A . 
       FIGS.  4 B and  4 C  illustrate further details of the relationship between the system connection cable  118  and its connected slip-ring assembly  300  and the cable storage drum assembly  206  ( FIG.  4 A ). The system connection cable  118  enters the slip-ring cover  120  through the grommet  119 , with its conductors connected to the cable-mounted female connector  308 . 
     Female connector  308  is mated with the PCB-mounted male connector  311 . The PCB  210  with its annular contact rings  306  ( FIG.  3 B ) is contacted by gold-plated springs  227 . The contact pins  226  contact the springs  227 , and the ends of the contact pins  226  are pressed against the annular contact rings  404  ( FIG.  2 D ) on the hub PCB  402  thus completing the connection between system connection cable  118  and cable storage drum assembly  206 . A clamp ring  411  attaches the hub cone  124  to drum  207  with screws  425 , securing a seal  451 . Circular bearing surfaces  421  and  423  are molded into the front and rear outer casings  102  and  104 . 
     Referring to  FIG.  4 C , the clamp ring  411  attaches the drum  207  to the hub cone  124  with a plurality of screws  425  deforming the seal  451 . The hub PCB  402  is seated on the seal  315 . The push-cable  103  is seen in cross-section retained by the two-eared clamp  453  and the cable retainer  427  under the hub shield  214 , which in turned is retained by a screw  433 . The drum  207  contains hub cone  124  and hub shield  214 . The hub PCB mount  406  deforms the seal  445  to the hub cone  124 . A separate push-cable PCB  429 , retained by screws such as  431 , extends toward the central axis of the hub cone  124  from below the hub shield  214 . A push-cable connector  435  is mounted on push-cable PCB  429  retained by screws  431  into which a push-cable plug  437  to which the push-cable conductors are joined, is inserted. Push-cable plug  437  and the conductors are retained by plastic plug retainer  439  and rubber plug seal  441 . The hub PCB  402  has a header-pin connection  443  connecting push-cable PCB  429  to hub PCB  402 . 
     In alternative embodiments of the present invention, the internal electronics could be configured to regulate power to the camera and its LEDs, provide drum rotation counting functions using magnets such as  405  and  407  ( FIG.  4 D ) on the slip-ring assembly  300 , be extended to include image capture and recording, GPS information management, a real-time clock, wireless connections to exchange data with a line and sonde locator, or transmit video images wirelessly. 
     Turning to  FIG.  4 D  slip-ring assembly  300  has the system connection cable  118  in cross section secured by two-eared clamp  313  ( FIG.  3 B ) and its leads connected to IDC female connector  308  plugged into mating connector  311  mounted on the PCB  210 . In one embodiment of the present invention, the paying out of push-cable  103  ( FIG.  1   ) occurs whenever hub cone  124  and cable storage drum assembly  206  rotate. The system enables measurement of this rotation by providing two neodymium rare-earth magnets  405  and  407  seated in provided molded recesses in slip-ring housing  208 . The combined fields of magnets  405  and  407 , which have the same additive orientation, are detected by at least one magnetic sensor  409  of two or more axes of detection embedded into a recess in hub cone  124  and connected electrically to a PCB such as  429  supported by hub PCB mount  406 . The detection of changed angles of the composite fields from magnets  405 ,  407  is translated electronically into a measurement of push-cable  103  payed out of or drawn into cable storage drum assembly  206 .  FIG.  4 D  illustrates the relative locations of the PCB  210 , the hub PCB  402  and push-cable PCB  429 , and contact pins  226 . 
     The view of  FIG.  5 A  further illustrates the operative mating of the two separable portions of the slip-ring mechanism of the present invention. Referring to  FIG.  5 A  slip-ring assembly  300  is seen from the rear side of rear outer casing  104  with contact pins  226  emerging from rubber contact seal  302 . Front outer casing  102  is opened to a horizontal position. Cable storage drum assembly  206  is moved part-way out from its enclosing rear outer casing  104  in order to reveal the slip-ring assembly  300  within rear outer casing  104 . The cable storage drum assembly  206  contains the camera assembly  105  with coil spring assembly  111  and push-cable  103  within drum  207 . The hub cone  124  and the hub shield  214  are seen within the removable cable storage drum assembly  206 . On the inside of rear outer casing  104 , the centrally located slip-ring housing  208  supports contact seal  302  from which spring loaded contact pins  226  emerge. Contact pins  226  are individually seated in springs detailed in  FIG.  3 A  which are in electrical contact with the PCB  210  ( FIG.  3 B ), associated with system connection cable  118  ( FIG.  2 D ). 
     When the cable storage drum assembly  206  is removed from rear outer casing  104 , the contact pins  226  from the removable system connection slip-ring assembly  300  are visible within the central region of the rear outer casing  104 . In  FIG.  5 A , the hand-held display and image capture device  122  is shown removed from the dock handle  110 . System interface plug  220  is shown not mated to the display and image capture device  122 . 
     Now referring to  FIG.  5 B , pipe inspection system  100  is viewed from the rear side outside the rear outer casing  104 , with front outer casing  102  opened to a horizontal position as in  FIG.  4 A . The removable cable storage drum assembly  206  including drum  207  is separated herein from rear outer casing  104 . In the central region of the cable storage drum assembly  206  can be seen the hub PCB  402  with three annular contact rings  404  supported by hub PCB mount  406  and the rigid structure of the hub cone  124 . The annular contact rings  404  are etched onto drum-side hub PCB  402  which connects to the conductors within the push-cable  103  ( FIG.  1   ) within the cable storage drum assembly  206 , the connections being protected by the molded hub shield  214  ( FIG.  2 C ). 
     System connection cable  118  connected to system interface plug  220  is shown entering the slip-ring assembly  300  ( FIG.  3 B ). The system interface plug  220  is shown at the end of system connection cable  118  not mated with display and image capture device input connector  504  in the hand-held display and image capture device  122 . 
     Referring now to  FIG.  6 A , a vertical section of the display and image capture device input connector  504  is shown with the system interface plug  220  connected to it. A circuit board  605  inside system interface plug  220  serves as the primary link between the camera assembly  105  and the hand-held display and image capture device  122 . In this example, the hand-held display and image capture device  122  is the commercially-available Perceptron® unit. Adaptation of the present invention to other display units will be readily apparent to those skilled in the art who understand the embodiments presented here. 
     Within the system interface plug  220 , circuit board  605  converts the 5-Volt signal from the Perceptron® into a 12 Volt power supply to power the camera&#39;s internal boards and LEDs. The video information received by the camera is also fed through circuit board  605  to the Perceptron® viewing window. When the user changes certain settings on the Perceptron display and image capture device  122 , this board  605  also translates these new settings to the camera assembly  105 . For example, the board incorporates a boost converter to control the LEDs&#39; brightness at the camera when the user changes brightness settings on the Perceptron®. A mini-DIN 9-pin connector  607  connects circuit board  605  display and image capture device to input connector  504 . Circuit board  605  and a base housing  613  are assembled and retained by screw  609 . 
     Referring to  FIG.  6 B  the system interface plug  220  is shown in a horizontal section, with system connection cable  118  entering the system interface plug  220  through rubber grommet  615 . The conductors within the system connection cable  118  are then connected to circuit board  605  on which Mini-DIN connector  607  is mounted connecting to the display and image capture device input connector  504  on the Perceptron® hand-held display and image capture device  122 . Additional screws  617  and  619  join the top housing  611  to the base housing  613  of the system interface plug assembly  220 . 
     Referring now to  FIG.  7   , the separable slip-ring assembly  300  enables an alternative system connection cable  118  to be easily inserted to enable connection to, for example, a different video monitor. In  FIG.  7    the slip-ring cover  120  is illustrated installed, and rear outer casing  104  ( FIG.  5 B ) is removed. The system connection cable  118  in this instance is configured with a system interface plug  220  for the Perceptron® hand-held display and image capture device  122 , system interface plug  220  so formed as to fit to the curve in the front of the display and image capture device  122  and connecting electronically with Perceptron® display and image capture device input connector  504  (not visible). Cover plate  128  and cable grip  129  are visible. 
     Turning to  FIG.  8 A , an alternate embodiment of our pipe inspection system  800  has the hand-held display and image capture device  122  ( FIG.  5   ) removed, with its system connection cable  118 , and in its place a different type of system connection cable  802  has been substituted. Carrying strap  808  in its folded configuration is shown. At one end of system connection cable  802  is the slip-ring assembly  300 , while at the other end a display system connector  806  for an industry-standard SeeSnake® monitor is connected. By simply rotating the slip-ring cover  120  ( FIG.  3 A ), which is rigidly attached to the slip-ring housing  208  ( FIG.  3 A ), the slip-ring assembly  300  may be removed from the system  800  complete with the system connection cable  802  and replaced with an alternatively configured system cable. This enables the system user to adapt the system to more than one display device by changing system connection cables. 
     Plastic molded feet  113  and  115 , mounted on the ends of cord-wrap arms  112 ,  114 , are aligned such that they extend outward the same distance as the snap-on molded feet  108  below them. This enables the system to be supported horizontally in use. 
       FIG.  8 B  illustrates the system  800  horizontally oriented and resting on feet  108 ,  113 ,  115  Rear outer casing  104  is now oriented downward. The display system connector  806  extends out from the slip-ring assembly (not visible) while the push-cable would normally be guided out of the front outer casing  102  through cable guide  126 . 
       FIG.  9 A  illustrates a variant of the present invention with the front shell removed for clarity. In  FIG.  9 A  cable storage drum assembly  900  has a system control keypad  902  seated at the outer surface of the hub  904 . In this embodiment, control keypad  902 , using membrane switches for water-resistance, is mounted on the end face of the central molded hub  904  in such a way that it is directly accessible from without when the outer casings such as  102 ,  104  are closed and latched. The controls are used to set up and operate software such as distance counting software, allowing overlays of stored text, locally defined counts based on temporary zero-points and other desired information to be displayed during a pipe inspection. Push-cable  908  is stored within drum shell  906 . Hub shield  214  is seated on the clamp ring  411  and serves to prevent coils of stored push-cable  908  from abrading the push-cable electrical linkage. 
     In  FIG.  9 B  cable storage drum assembly  900  is viewed in section. Drum shell  906  contains coiled layers of push-cable  908 . The control keypad  902  is mounted on the projecting face of hub  904 . Ribbon cable  910  connects control keypad  902  to the counter PCB  914 . Clamp ring  411  is a molded ring which retains the hub assembly. Inside hub  904  a PCB mount  916  supports a slip-ring PCB  912  on the left side of  FIG.  9 B , and a counter PCB  914 . 
     In  FIG.  10   , an exploded perspective view of the overall pipe inspection system  1000  is shown using the hub-key pad innovation described in  FIG.  9 A . Cable storage drum assembly  900 , including drum shell  906  with central molded hub  904  retained therein, contains coiled stored push-cable  908  terminating in an inspection camera assembly  905 . Front outer casing  102  is in its open position. Central molded hub  904  supports control keypad  902 . Hub shield  214  protects the electrical linkage from the base of the push-cable to the control circuitry within the hub. Display and image capture device  122  connecting by means of interface plug  220 , dock handle  110 , cord-wrap arms  112 ,  114 , latch  106 , rear outer casing  104 , slip ring assembly  300 , seal  302 , contact pins  226 , slip-ring housing  208 , are as described in the embodiment shown in  FIGS.  2 C,  2 D, and  2 E . The slip-ring configuration is modified in this embodiment to accommodate the sensing magnets as shown in  FIG.  11 A . 
     Note that the cable storage drum assembly  900 , push-cable  908  and camera assembly  905  of the pipe inspection system  1000  in  FIG.  10    are a different specification than the drum, cable and camera in  FIGS.  1  and  5 A , with a longer and slightly stiffer push-cable  908 , a larger camera assembly  905 , and the addition of the keypad  902 . The simple replacement of the drum in the clamshell case advantageously allows the user to rapidly deploy a different system for different purposes, such as inspecting a longer run of pipe, for example, with less constrained turns in it. 
     In  FIGS.  11 A and  11 B , system connection cable  1138  leading from the hand-held display and image capture device  122  ( FIG.  10   ) enters the slip-ring cover  1102  through an opening between the two grip recesses  1140  and passes through a grommet  1142 . The system connection cable  1138  is secured onto slip-ring cover  1102  by, for example, a two-eared clamp  1106  ( FIG.  11 B ), and its conducting leads are connected electrically to a female plug  1104  ( FIG.  11 B ). The female plug  1104  mates with a three-pin IDC male connector  1112  mounted on the back side of a fixed PCB  1110 . Three annular contact rings  1113  are formed on the front side of the PCB  1110  and lead to the pins of IDC male connector  1112  on the back. Six contact pins  1120  of a graphite-silver compound are biased by corresponding gold-plated springs  1118 . Springs  1118  contact against the three annular contact rings  1113 , two on each of the contact rings  1113 . The use of dual spring-loaded contacts for each of the annular contact rings  1113  reduces contact noise in the transmission of electrical signals. The contact pins  1120  and springs  1118  are mounted in corresponding cylindrical sleeves  1126  molded in a central wall portion of a cylindrical slip-ring housing  1116 . Contact pins  1120  and springs  1118  are retained in cylindrical sleeves  1126  by a rubber contact seal  1130  and a retainer  1134 . Rubber contact seal  1130  is designed so that it seals the contact pins  1120  in a water-tight fashion as they pass through the rubber contact seal  1130 . The slip-ring housing  1116  is formed with peripheral locking keys such as  1122  which are engaged by mating features on the rear outer casing  104  ( FIG.  10   ). The slip-ring assembly  1100  can be manually inserted and twist-locked into the center of the rear outer casing  104  ( FIG.  10   ). The outer casings  102  and  104  of the clam-shell housing can then be latched together. The contact pins  1120  are then held by the force of the springs  1118  in electrical contact with a plurality of contact rings on slip-ring PCB  912  ( FIG.  9 B ) within the cable storage drum hub  904  providing conductive paths between the push-cable  908  and the system connection cable  1138 . Magnets  1136  are seated in pockets  1128  formed into slip-ring housing  1116  and retained therein by inserted clips. Screws  1124  attach slip-ring housing  1116  to slip-ring cover  1108 . Screws  1132  attach retainer  1134  inside a protective well formed in slip-ring housing  1116 . 
       FIG.  11 C  illustrates in a section view the joining of system connection cable  1138  to the slip-ring assembly  1100  after the system connection cable  1138  passes through a sealing grommet  1142 . The electrical leads of the system connection cable  1138  are attached to female plug  1104  and thus to the pins of IDC male connector  1112 . Slip-ring cover  1102  forms a seal with O-ring  1108 . Contact pins  1120  are connected to the inputs from system connection cable  1138  and female plug  1104  by means of PCB  1110  and are tensioned in contact with the hub annular contact rings by springs  1118 . Rubber contact seal  1130  through which the contact pins  1120  protrude serves to seal the pins against dust or moisture. PCB  1110  is attached by screws  1114  to slip-ring housing  1116 . 
     In the preferred embodiment camera assembly  905  ( FIG.  10   ) or camera assembly  105  ( FIG.  1   ) has a small built-in dipole sonde transmitter. In some embodiments, the camera may be replaced with a high-powered dedicated sonde unit whose higher power transmissions allow the sonde to be located in more remote or more shielded locations when down-pipe, using a standard locator. In some embodiments the replacement unit may be a smaller dedicated sonde unit able to fit into smaller spaces into which the standard camera head cannot fit. In such embodiments, the cable with a dedicated sonde attachment may be installed in a removable cable storage drum assembly such as  900  ( FIG.  10   ). 
     A cable with a dedicated sonde attached may be designed in some embodiments to enable a line-locating frequency such as 33 kHz to be transmitted along it while the sonde is also operating, thus allowing a locator operator to trace the line and locate the sonde at the end of it in a single operation using an appropriately designed locator. In such as embodiment the sonde may be in always-on configuration rather than switchable from the keypad  902 . Any one of these configurations may be built into a replaceable drum assembly and rapidly mounted into or removed from the clamshell case of the present invention to suit the needs of the operator. In  FIG.  12   , system  1200  includes cable storage drum assembly  1210  in which the cable is connected to a dedicated sonde head  1212  rather than a camera head. Sonde head  1212  provides a more powerful sonde transmission to enable locating the head in deeper or more shielded locations. Alternatively, a sonde head designed for minimum size may be used allowing the sonde to reach into areas too confined for a standard camera head. Because the drum assembly  1210  is readily removable and replaceable, a special-purpose drum assembly such as  1210  as shown in  FIG.  12    is advantageously easy to deploy when needed in inspection and location operations. 
     In some embodiments of the present invention, the dipole sonde transmitter may be built into the camera head construction. In  FIGS.  13 A  and  FIG.  13 B  the construction of the sonde relative to the camera head is visible. Several innovative principles are illustrated by means of which the built-in sonde can be constructed with a minimal footprint in order to enable the smallest possible camera diameter for the inspection system while retaining sonde transmission power. In  FIG.  13 A  the camera assembly  905  is illustrated in a partially exploded view in which camera window assembly  1310  and rear casing  1302  have been moved away from the sonde assembly  1350 . It will be noted that sonde assembly  1350  is constructed substantially surrounding camera module  1312 , creating an advantageously compact footprint. Sonde bobbin  1352  is a plastic shell formed of two halves which lock into place around the lens assembly and camera module  1312 . A core of Metglas  1354  laid into a tubular form is wound onto the sonde bobbin  1352  and sealed into place with a layer of Kapton tape  1356  ( FIG.  13 B ). The Metglas core  1354  serves to maximize the power of the coil&#39;s transmission when energized by acting as a high-permeability core which enhances field strength. Sonde coil  1358  likewise substantially surrounds the camera module  1312 . The Metglas core  1354  is preferably formed from Metglas® 2714A annealed alloy tape rolled into a tubular configuration that also surrounds the camera module  1312 . The Metglas alloy incorporated in this tape is a metallic glass alloy that differs from traditional metals in that it has a non-crystalline structure and possesses unique physical and magnetic properties that combine strength and hardness with flexibility and toughness. The bonded sonde coil  1358  is situated around the layer of Kapton  1356 . A layer of shrink-tubing  1360  is positioned and made to shrink into place around the sonde coil  1358 . The housing of the sonde is preferably made of a material of low conductivity and low magnetic permeability to minimize eddy current losses and avoid shunting the field. When powered under the control of a circuit mounted on the camera circuit board  1320 , the sonde emits a 512 Hz frequency, for example. The integrated sonde allows the axial length of the sonde coil  1358  to be minimized while still providing adequate radiated signal strength for underground locating operations. 
     In addition to the improved form-factor achieved by building the sonde around the camera module  1312 , additional improvements in the design of the camera&#39;s power transmission system may be seen in  FIGS.  13 A and  13 B . Spring-loaded pins  1314  ( FIG.  13 A ) on either side of the camera module  1312  transfer power to the LEDs via a circuit board  1322  within the front bezel and window assembly  1310 . Additional spring-loaded pins  1318  transfer power from the rear connectors of the camera head assembly to the CMOS PCB  1316  which is connected as well to the camera circuit board  1320 . The use of spring-loaded pins  1314  and  1318  allows the camera head to be rapidly disassembled for repair as it obviates the need for unplugging connectors and reduces the form factor of the assembly. 
     Clearly, other embodiments and modifications of this invention may occur readily to those of ordinary skill in the art in view of these teachings. For example, in a converse alternative embodiment of the pipe inspection system  100  ( FIG.  1   , et al.) the spring biased contact pins  226  of the slip-ring assembly  300  ( FIG.  3 A,  3 B ) could be mounted to the slip-ring cover, for example, and the contact rings  306  could be mounted in the slip-ring housing  208 . It is advantageous to put the spring pins on the cable side of the interface as the single PCB is easier to seal, and doing so enables the use of interchangeable drums, for example using different types of cable assemblies. 
     While embodiments of the present invention have been described in detail, modifications and adaptations thereof will occur to those skilled in the art of designing pipe inspection systems. For example, the basic system could have a converse configuration in which the contact rings are mounted on the cable storage drum and the contact pins are mounted on the housing. Therefore, the protection afforded this invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings.