Abstract:
An interconnect apparatus for electrically connecting Telco wires to subscriber wires is arranged and configured to withstand overcurrent and overvoltage conditions. The interconnect apparatus includes a jack, a first set of contacts, and a first set of by-pass conductors. The first set of by-pass conductors is electrically connected to the first set of contacts and has a greater current carrying capacity than the first set of contacts. The interconnect apparatus further includes a second set of by-pass conductors and a plug. The second set of by-pass conductors is electrically connected to the first set of by-pass conductors when the plug and jack are engaged. The second set of by-pass conductors may also have a greater current carrying capacity than the first set of contacts. Preferably, the first set of by-pass conductors is spaced sufficiently apart and the second set of by-pass conductors is spaced sufficiently apart to substantially eliminate arcing.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to telephone wiring interconnect apparatus and method, and more particularly, to an interconnect apparatus of the type commonly used in a network interface device (NID), such as a protected terminal device (PTD) or line module. The apparatus is used to interconnect wiring from a telephone service provider with subscriber wiring. Specifically, the present invention relates to an improved telephone interconnect apparatus that can withstand overcurrent and overvoltage conditions.  
           [0003]    2. Description of the Related Art  
           [0004]    Telephone service is provided by a telephone company (“Telco”) to a number of different subscribers. Each subscriber may purchase as many separate telephone lines as desired and equip his or her home or business with various telephone equipment. Subscribers are responsible for proper operation of the telephone equipment and the Telco is responsible for proper operation of the telephone network up to the interface between the Telco wiring and the subscriber wiring. Therefore, it is desirable to provide a telephone network interface device (NID) to serve as demarcation point between the Telco wiring and the subscriber wiring. FIG. 1 illustrates a typical prior art NID  10 . The NID  10  may be mounted to an exterior wall of a house or commercial building  2 . The Telco wiring  4  enters the NID and terminates in a locked inner enclosure  12 , which is shown in the open position for purposes of clarity. The Telco wiring  4  may come in a bundle of, for example, twisted pair wires. The bundle of twisted pair wires can be split and each pair terminated into a connector block within the inner enclosure  12 .  
           [0005]    The inner enclosure  12  is preferably locked to prevent unauthorized access by the subscriber or vandals. Typically, each subscriber telephone line is serviced by one set of twisted pair wires, commonly referred to as the “tip” and “ring” wires. Each of the twisted pair wires is electrically connected to an interconnect apparatus, such as a protected terminal device (PTD) or line module  100 , located adjacent the inner enclosure  12 . In other words, the tip and ring wires from one twisted pair are inserted into one end of the interconnect apparatus  100  and electrically coupled to a pair of conductors within the apparatus. The interconnect apparatus  100  is typically a modular device that can be mounted in the NID and easily replaced if rendered inoperable.  
           [0006]    Referring to FIGS. 2A to  2 E, a prior art line module  100  is shown in greater detail. The line module  100  has a housing  102  and a cover  104  that can pivot between a closed position, as shown in FIG. 2A, and an open position, as shown in FIG. 2B. The housing  102  of the line module  100  has a pair of insertion channels  124  that allow the Telco wires  4  to be electrically coupled with a pair of contacts  122  (FIG. 2E) located in an integrated jack  112 . As shown, the jack  112  is a conventional RJ-11 jack. The cover  104  may be connected to the line module  100  by a hinge  120  (FIG. 2C) so that the cover  104  can be rotated away from the housing  102  of the line module  100  to permit access to the jack  112 . As mentioned, the jack  112  has a pair of contacts  122  that are electrically coupled to the tip and ring wires. Likewise, plug  110  attached to the cover  104  has a complementary pair of conductors  114  that make contact with the jack contacts  122  when the plug  110  is engaged in the jack  112 . The subscriber wires  6  are connected to a pair of terminals  118  provided on a portion of the line module  100  known as the bridge  108 . The plug conductors  114  are also electrically coupled to the terminals  118 . Thus, when the cover  104  is closed, an electrical circuit is completed between the Telco wires  4  and the subscriber wires  6 . When the cover  104  is opened, the subscriber wires  6  are disconnected from the Telco wires  4 . However, a test plug (not shown) can be plugged into the jack  112  to determine if the Telco wires  4  up to the line module  100  are conducting properly. As shown in FIGS. 2C and 2D, the bridge  108  is removable, and thus, replaceable if rendered inoperable. However, line module  100  may also be provided with a non-removable bridge.  
           [0007]    The spacing and size of the plug conductors  114  and the jack conductors  122  are sources of failure when the line module  100  is subjected to overvoltage and overcurrent conditions. For example, a lightning strike on a telephone line may cause a voltage spike that will result in an electric arc between the tip and ring contacts of either the jack or the plug. In other words, the tip and ring wires are at different voltages. An overvoltage event magnifies the difference and may cause an electrical arc to jump between the closely spaced contacts. The contacts in RJ-11 plugs and sockets are relatively small gauge, typically 24 AWG or 25 AWG. An overcurrent event may result in the plug and jack conductors in contact with each other welding together. In either event, the line module  100  is rendered inoperable.  
           [0008]    U.S. Pat. No. 5,153,910 discloses an example of a protected terminal device (PTD) for a NID used to connect Telco wiring with subscriber wiring. When the cover of the PTD is closed, an actuator presses a set of conductors into contact with a complimentary set of thin lead contacts. The lead contacts in turn are connected to the Telco wiring. The subscriber wiring is connected through two terminal screws to the set of conductors. Thus, an electrical signal path is created from the subscriber wiring, through the terminal screws and conductors, and into lead contacts. While this simple design allows for easy connection of the subscriber and Telco wiring, it does not address the causes of the arcing or welding failure modes. Specifically, arcing may occur between the lead contacts because they are closely spaced. Furthermore, the small gauge lead contacts may become welded to the conductors.  
           [0009]    It is thus apparent a particular need exists for an improved interconnect apparatus that can withstand overcurrent conditions and overvoltage conditions.  
           [0010]    It is further apparent that a particular need exists for an improved interconnect apparatus including a test plug that remains functional when a cover is removed from the bridge and the electrical circuit between the Telco wires and the subscriber wires is broken.  
           [0011]    It is further apparent that a particular need exists for an improved interconnect apparatus that can withstand overvoltage and overcurrent conditions regardless of whether the bridge is fixed or removable.  
         BRIEF SUMMARY OF THE INVENTION  
         [0012]    The present invention relates to an improved interconnect apparatus, such as a protected terminal device (PTD) or line module, that can withstand overcurrent and overvoltage event, such as a lightening strike. The interconnect apparatus may, for example, be mounted within a conventional network interface device (NID). The interconnect apparatus uses large gauge by-pass conductors for signal transmission from the Telco to the subscriber rather than small gauge contacts. However, the jack located in the housing of the interconnect apparatus retains standard sized contacts that will interface with conventional test plugs.  
           [0013]    In one embodiment, the improved interconnect apparatus includes a housing having a removable bridge and cover assembly. The bridge includes terminals for connection to the subscriber wires. The housing includes a jack having a first set of by-pass conductors and a first set of contacts. The first set of by-pass conductors include one conductor for the tip wire and one conductor for the ring wire. The first set of by-pass conductors oppose a second set of by-pass conductors located on a plug. The plug can be attached to the cover. When the plug is engaged with the jack, the first set of by-pass conductors electrically couple with the second set of by-pass conductors to complete an electrical circuit between the Telco wires and the subscriber wires. The plug, however, does not require a second set of contacts to complete an electrical circuit with the first set of contacts. When the cover is opened, the first and second set of by-pass conductors are uncoupled and the electrical circuit therebetween is broken. In the event of an overcurrent condition, the first and second sets of by-pass conductors can withstand the current surge because of their increased dimensions. In the event of an overvoltage condition, arcing is largely inhibited by the spacing (i.e., separation) between the by-pass conductors on the plug and jack, and a non-conductive grease between the first set of contacts. Further, the plug may have a ridge that fits between, and thus, isolates the contacts on the jack.  
           [0014]    In another embodiment, the improved interconnect apparatus has a cover pivotally hinged on the housing to permit access to a jack. The cover is provided with a dummy plug or actuator. The dummy plug does not have either a second set of by-pass conductors or a second set of contacts. Instead the housing of the interconnect apparatus contains both a first set of by-pass conductors and a second set of by-pass conductors. The first and second sets of by-pass conductors are mounted within the housing substantially parallel, but apart from one another. Further, one or both sets of conductors can be cantilevered to provide an elastic spring force when one set is moved in the direction of the other. The first set of by-pass conductors is electrically coupled to a first set of contacts exposed in the jack. The first set of by-pass conductors is further connected to the Telco wires, while the second set of by-pass conductors is connected to the subscriber wires. When the dummy plug is inserted into the jack, the tip of the plug forces one set of the by-pass conductors into contact with the other set of by-pass conductors. An electrical circuit is thereby completed between the Telco wires and the subscriber wires. However, when the cover is opened and the plug is removed, the sets of by-pass conductors move apart due to the elastic spring force and the electrical circuit is broken. Furthermore, the first set of contacts in the jack is exposed and a conventional test plug can be inserted. The jack, however, is dimensioned to prevent the tip of the test plug from creating contact between the first and second sets of by-pass conductors. Arcing is largely inhibited by providing a non-conductive grease between the first set of contacts.  
           [0015]    The present invention relates broadly to telephone wiring interconnect apparatus and methods. As such, the invention relates to more than the improved interconnect apparatus and the specific wiring configuration disclosed and shown herein. In particular, a method of connecting Telco wires to subscriber wires through the improved interconnect apparatus is also disclosed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    One or more preferred embodiments of the invention will be described more fully below and illustrated in the accompanying drawings in which:  
         [0017]    [0017]FIG. 1 is a perspective view of a prior art network interface device (NID) mounted to the exterior wall of a house or commercial building;  
         [0018]    [0018]FIGS. 2A to  2 D are side elevation views and FIG. 2E is a top plan view of a prior art interconnect apparatus, namely a line module, having a removable bridge;  
         [0019]    [0019]FIGS. 3A and 3B are perspective views of the jack and plug of a preferred embodiment of an interconnect apparatus according to the invention;  
         [0020]    [0020]FIGS. 4A and 4B are perspective views of a standard RJ-11 style test plug engaging the first contacts in the jack of the interconnect apparatus of FIGS. 3A and 3B;  
         [0021]    [0021]FIGS. 5A, 5B, and  5 C illustrate various locations that the by-pass conductors may be positioned on the jack and plug of the interconnect apparatus of FIGS. 3A and 3B;  
         [0022]    [0022]FIGS. 6A, 6B, and  6 C are perspective views of another preferred embodiment of an interconnect apparatus according to the invention wherein the by-pass conductors are mounted within the housing of line module;  
         [0023]    [0023]FIGS. 7A, 7B, and  7 C illustrate an alternate plug for use with the interconnect apparatus of FIGS. 6A, 6B, and  6 C; and  
         [0024]    [0024]FIGS. 8A, 8B, and  8 C are detailed perspective views of the wiring configuration of the interconnect apparatus of FIG. 6A, 6B, and  6 C illustrating the orientation of the by-pass conductors in the opened, closed, and test positions, respectively. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    The present invention relates to a telephone wiring interconnect apparatus of the type commonly used in a network interface device (NID), such as a protected terminal device (PTD) or line module. The interconnect apparatus acts as a demarcation point between the wiring of a Telco provided telephone line and the wiring from a subscriber&#39;s telephone equipment. Since the interconnect apparatus serves as a point of demarcation, or separation, it is important that the interconnect apparatus also provide a means for a conventional test plug to determine whether the Telco wiring is providing a “dial tone” to the subscriber.  
         [0026]    [0026]FIGS. 3A and 3B illustrate a first embodiment of an interconnect apparatus  200  according to the present invention. The interconnect apparatus  200  may, for example, be employed in a PTD or a line module that is mounted in a NID in a conventional manner. The interconnect apparatus  200  has a main housing (not shown), a cover  204 , a plug  210  fixed to the cover  204 , and a jack  212  disposed within the housing. The cover  204  preferably is movably attached to the housing, and most preferably, is hinged to the housing about a distal axis (not shown). For simplicity of illustration and clarity, only the plug  210 , the jack  212 , and a portion of the cover  204  are shown. The jack  212  has a first set of by-pass conductors  232 . The conductors  232  may be formed from any conductive metal, such as phosphor bronze or beryllium copper. The metal chosen should have high electrical conductivity and elastic spring force for a purpose to be described. The conductors  232  should be spaced and sized to withstand both an overcurrent and an overvoltage condition. Specifically, the by-pass conductors should be able to pass a 2000 amp, 3000 volt test for a period of at least 250 milliseconds.  
         [0027]    Each of the by-pass conductors  232  is provided with a detent to allow for positive elastic registration with a mating by-pass conductor  230  disposed on the plug  210 . Each of the by-pass conductors  232  has an exposed by-pass contact  232   a  extending beneath the floor of the jack  212 . The Telco wires  4  are electrically coupled to the by-pass prongs  232   a.  The jack  212  may have a generally rectangular shape with a front surface where a first set of contacts  222  (FIG. 3B) is located. As shown, the first set of by-pass conductors  232  are positioned on either of the first contacts  222  along the sides of the jack  212 . Likewise, the second set of by-pass conductors  230  is positioned on the sides of the plug  210 . As discussed hereinafter, the by-pass conductors  232 ,  230  can be located on other surfaces of the jack  212  and the plug  210 , respectively.  
         [0028]    The cover  204  has an integrally formed plug  210 . The plug  210  has a second set of by-pass conductors  230  that are located so as to engage the first set of by-pass conductors  232  when the plug  210  engages the jack  212 . The second set of by-pass conductors  230  may also be provided with complimentary detents to allow for positive elastic registration with the first set of conductors  232 . Each of the second set of by-pass conductors  230  also has a pair of exposed by-pass contacts  230   a  that are electrically coupled to the subscriber&#39;s wiring  6  (FIG. 3B). As previously described, the second set of by-pass conductors  230  may also be electrically coupled to a set of terminals  218  on a bridge  208  to which the subscriber wires  6  are connected.  
         [0029]    The first set of contacts  222  of the jack  212  is best shown in FIG. 3B. However, the plug  210  does not require a corresponding pair of “second” contacts. This is because the signal being transmitted to and from the subscriber&#39;s equipment is carried by the by-pass conductors  232  and  230 , and not the contacts  222 . Regardless, the plug  210  may further have a thin ridge formed thereon between recesses  234  to provide some physical, dielectric or non-conductive barrier between the first contacts  222  on the jack. A non-conductive grease is also provided on the top and front surfaces of the jack  212  between the first contacts  222 . Thus, if a voltage surge occurs as a result of an overvoltage event, arcing between the first contacts  222  is largely inhibited.  
         [0030]    When the cover  204  is opened, the plug  210  disengages from the jack  212  so that a conventional test plug  50  can then be placed into the open jack  212 , as shown in FIGS. 4A and 4B. As previously mentioned, it is common for an interconnect apparatus, such as a PTD or line module, to be provided with an RJ-11 style jack. Further, it is common that test plugs be a standard RJ-11 style plug that engages the RJ-11 jack provided on the interconnect apparatus. Thus, the dielectric plug  52  of the test plug  50  has a second set of conductive contacts  54  that electrically couple with the first set of contacts  222  in the jack  212 . The first set of by-pass conductors  232  on the jack  212  is positioned so as not to impede the insertion of the plug  52 . The lateral surfaces of the dielectric plug  52  simply slide against the first set of conductors  232 .  
         [0031]    While this disclosure has illustrated described the by-pass conductors  230 ,  232  as being positioned along the sides of the plug  210  and jack  212 , respectively, on either side of the first contacts  222 . However, the conductors  230 ,  232  can be located on other mating surfaces as well. Various alternative placements of the by-pass conductors  230 ,  232  are illustrated in FIGS. 5A, 5B, and  5 C. For example, pairs of first and second by-pass conductors  262 ,  264  of an interconnect apparatus  260  may be located on the end of the plug  210  and the floor of the jack  212 , respectively, as shown in FIG. 5A. The first and second by-pass conductors  272 ,  274  of an interconnect apparatus  270  may be located on surfaces of the plug  210  and the jack  212 , respectively, that are parallel to the first set of contacts  222 , as shown in FIG. 5B. Furthermore, the first and second conductors  282 ,  284  of an interconnect apparatus  180  may be located on opposite surfaces of plug  210  and jack  212 , respectively, as shown in FIG. 5C.  
         [0032]    A second embodiment of an interconnect apparatus according to the invention includes first and second by-pass conductors positioned within the housing of a conventional line module. FIGS. 6A, 6B, and  6 C illustrate a portion of a line module  300  having a housing  304  and a cover  302  hinged to the housing  304 . The housing  304  may be integrally formed or may consist of two or more components, such as a lower barrier and a jack top, in a known manner. The cover  302  has a non-conductive dummy plug  306  that may also be referred to as an “actuator” or “plunger.” Telco wires  4  are electrically coupled to both a first set of by-pass conductors  310  and a first set of contacts  312  positioned within a recess formed in the housing  304 . A second set of by-pass conductors  308  is also positioned within the recess formed in the housing  304  such that the by-pass conductors  308  are closely separated from the by-pass conductors  310 . As previously described, a non-conductive grease is provided within the recess of the housing  304  to largely inhibit arcing between the first set of contacts  312 . For purposes of clarity and illustration, the line module  300  is shown sectioned between the first set of by-pass conductors  310 , the first set of contacts  312 , and the second set of by-pass conductors  308 .  
         [0033]    As the cover  302  is closed, the dummy plug  306  is received within the recess of the housing  304 . The dummy plug  306  has a lower portion  314  that is characterized with an engaging portion  316 . The engaging portion  316  contacts and forces the second by-pass conductors  308  downwardly until electrical contact is established with the first by-pass conductors  310 . When the integrity of the Telco wiring must be determined, the cover  302  can be opened to expose the first set of contacts  312  within the recess formed in the housing  304 . A conventional test plug  50  of the type as previously described, can then be inserted in the housing  304 , as shown in FIG. 6C. However, a standard RJ-11 style test plug does not have an equivalent to the engaging portion  316  of the dummy plug  306 . Furthermore, the travel of bottom surface  56  is limited by the inner surface  320  of the housing  304 . Accordingly, the first and second by-pass conductors  310 ,  308  do not make contact with one another during the integrity test.  
         [0034]    As shown in FIGS. 7A, 7B and  7 C, an alternative dummy plug  350  made of a non-conductive material can be used to ensure that a sufficient amount of pressure is continuously exerted on the second by-pass conductors  308 . During manufacture, the accumulation of allowable tolerances can result in the dummy plug  350  not extending into the recess formed in the housing  304  far enough when cover  302  is closed to cause the by-pass conductors  308 ,  310  to make sufficient electrical contact. Furthermore, over time, plastic material may “creep” and deform its shape. Therefore, a linear, elastic spring  352  can be used to augment the force applied to the by-pass conductors  308  by the dummy plug  350  when the cover  302  is closed. In particular, the dummy plug  350  is movable relative to the cover  302 . The spring  352  is sized to exceed the elasticity of the conductors  308 ,  310 . Specifically, the spring constant of spring  352  is slightly greater than the elastic constant of the cantilevered by-pass conductors  308 . Thus, when the cover  302  is closed, the spring  352  will apply any additional force necessary to ensure that the conductors  308 ,  310  maintain sufficient electrical contact to couple the Telco wires  4  and the subscriber wires  6  regardless of manufacturing tolerances or creep effects.  
         [0035]    [0035]FIG. 7A illustrates the relative positions of the first and second by-pass conductors  310 ,  308  when the cover  302  is in the open position and the engaging portion  356  of the lower portion  354  of the dummy plug  350  has not engaged the conductors  310 ,  308 . The spring  352  is in an uncompressed state. In FIG. 7B, the cover  302  is shown partially closed and the engaging portion  356  of the dummy plug  350  has overcome the elastic constant of the cantilevered by-pass conductors  308  so that by-pass conductors  308  and  310  are in contact with one another. The spring  352 , however, remains in the uncompressed state. Finally, in FIG. 7C, the cover  302  is shown fully closed and the spring  352  is compressed to produce a pre-load on the dummy plug  350 . The pre-load force exerted by the spring  352  on the by-pass conductors  308  through the engaging portion  356  of the dummy plug  350  ensures that the by-pass conductors  308 ,  310  maintain sufficient electrical contact to couple the Telco wires  4  and the subscriber wires  6  despite the build-up of manufacturing tolerances or creep of the plastic material that may occur over time.  
         [0036]    [0036]FIGS. 8A, 8B, and  8 C are detailed perspective views of the wiring configuration of the interconnect apparatus  300  illustrating the orientation of the first and second by-pass conductors  310 ,  308  in the opened, closed, and test positions, respectively. Specifically, FIG. 8A illustrates the relative positions of the by-pass conductors  310 ,  308  when the cover  302  is opened and the dummy plug  306 ,  350  does not extend into the recess formed in the housing  304 . FIG. 8B illustrates the relative positions of the by-pass conductors  310 ,  308  when the cover  302  is partially or fully closed and the dummy plug  306 ,  350  is received within the recess formed in the housing  304 . In this configuration, second by-pass conductors  308  are forced into contact with first by-pass conductors  310  to establish an electrical connection between the Telco wires  4  and the subscriber wires  6 . Finally, FIG. 8C illustrates the relative positions of the by-pass conductors  310 ,  308  when the cover  302  is opened and the test plug  50  is received within the recess formed in the housing  304 . In this configuration, second by-pass conductors  308  are not forced into contact with the first by-pass conductors  310 , and thus, the Telco wires  4  are not electrically coupled with the subscriber wires  6 .  
         [0037]    In operation, a Telco can utilize an interconnect apparatus according to the invention to electrically couple Telco wires to subscriber wires in a manner that will not fail in the event of an overcurrent or an overvoltage condition. Specifically, a preferred embodiment of a method according to invention includes the first step of providing Telco wiring, for example from a central office or distribution location, to a NID, for example mounted on the exterior wall of a house or commercial building. Preferably, the multiple twisted pairs of the Telco wiring is then separated into individual pairs of tip and ring wires. At least one pair of such tip and ring wires is next electrically connected to an interconnect apparatus, such as a PTD or line module, as previously described. Specifically, the tip and ring wires are connected to a first set of by-pass conductors that are electrically coupled to a first set of contacts wherein the first set of by-pass conductors are made of larger gauge wire than the first set of contacts. Subscriber wires are then electrically coupled to the interconnect apparatus or, for example, to a set of terminals provided on the housing of the interconnect apparatus. As previously described, the second set of by-pass conductors are then moved into contact with the first set of by-pass conductors. Thus, an electrical circuit is established between the Telco wires and the subscriber wires across the first and second by-pass conductors of the interconnect apparatus.  
         [0038]    While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of invention. Accordingly, it is intended that the appended claims encompass any alternative embodiments of the invention not disclosed herein that are within the ordinary skill of a person knowledgeable in the art of electrical wire connectors.