Fiber optic splice and distribution enclosure

An enclosure for housing fiber optic splices between a fiber optic distribution cable and fiber optic customer drop cables includes a first door providing access to a first area of the enclosure housing couplers for receiving terminals of customer drop cables. The enclosure also includes a second door providing access to a second area of the enclosure for accommodating slices in one or more distribution cables. The second area is not accessible via the first area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an enclosure for fiber optic cables. More particularly, the present invention relates to a field-based enclosure, where a fiber optic distribution cable is spliced to one or more fiber optic customer drop cables.

2. Description of the Related Art

In the communications industry, fiber optic communication is becoming very popular. Fiber optic cables offer higher bandwidth and lower signal loss compared to conventional twisted pair cables and coaxial cables. In a typical fiber optic cable system for providing communication services to customers, a fiber optic distribution cable which may contain four, eight or more optical fibers is buried underground along a street or perhaps strung above ground along utility poles. At geographically spaced intervals, a technician splices a fiber optic customer drop cable to a fiber of the distribution cable. For example, at a property line between a first and second office building, the technician may tap into the distribution cable and connect several customer drop cables for the first office building and several customer drop cables for the second office building to a single one of the optical fibers in the distribution cable.

The splices must be protected from the elements. Typically, the splices are housed inside an underground enclosure or vault, such as the vault illustrated in U.S. Pat. No. 5,652,820, which is hereby incorporated by reference.

SUMMARY OF THE INVENTION

Applicants have appreciated one or more drawbacks associated with the designs of the prior art. The typical vault has one access mechanism to open it. Opening the vault exposes the splices of the distribution cable or cables, the splitter for the customer drop cables, and the connections to the customer drop cables. Applicants have appreciated that installers and service technicians would desire separate doors to access separate areas within the enclosure. Applicants have appreciated that it is advantageous to separate the distribution side of the enclosure from the drop side of the enclosure, so as to organize the areas within the enclosure to better facilitate installation, servicing and maintenance procedures. Also, the distribution side door could be lockable to prohibit access to the distribution cable(s) and/or splitter(s), such that those parts are not accessible to the customer drop side installers so that the distribution cable(s) and/or splitter(s) will not be tampered with or damaged when installing or servicing customer drop cables.

Applicants have also appreciated a need in the art for an enclosure which is simple in design, rugged, moisture resistant, easy to manufacture and/or inexpensive to manufacture.

It is an object of this invention to address one or more of the drawbacks of the prior art vaults and/or one or more of the Applicants' appreciated needs in the art.

The present invention provides an enclosure for housing fiber optic splices between a fiber optic distribution cable and fiber optic customer drop cables which includes a first door providing access to a first area of the enclosure housing couplers for receiving terminals of customer drop cables. The enclosure also includes a second door providing access to a second area of the enclosure for accommodating splices in one or more distribution cables. The second area is not accessible via the first area.

These and other objects may be accomplished by a fiber optic cable splice enclosure comprising: a first access door attached to said enclosure and having a closed condition and an open condition which provides access to a first area within said enclosure for housing at least one fiber optic customer drop cable; a second access door attached to said enclosure and having a closed condition and an open condition which provides access to a second area within said enclosure for housing at least one fiber optic distribution cable, wherein said second area is manually inaccessible from said first area; a plurality of fiber optic couplers located within said first area for receiving terminals of customer drop cables; and a splitter residing within a portion of said enclosure, said splitter including a fiber optic input and a plurality of fiber optic outputs, several of said plurality of fiber optic outputs being respectively coupled to individual couplers of said plurality of fiber optic couplers.

Also, these and other objects may be accomplished by a fiber optic cable splice enclosure comprising: a first access door attached to said enclosure and having a closed condition and an open condition which provides access to a first area within said enclosure for housing at least one fiber optic customer drop cable; a second access door attached to said enclosure and having a closed condition and an open condition which provides access to a second area within said enclosure for housing at least one fiber optic distribution cable, wherein said second area is manually inaccessible from said first area; a plurality of fiber optic couplers located within said first area for receiving terminals of customer drop cables; a third area formed between said first area and said second area, wherein said third area is bordered by a first bulkhead between said first area and said third area and a second bulkhead between said second area and said third area; a splitter residing within said third area, said splitter including a fiber optic input and a plurality of fiber optic outputs, several of said plurality of fiber optic outputs being respectively coupled to individual couplers of said plurality of fiber optic couplers; a plurality of first holder slots formed in or attached to said first bulkhead and facing said first area for holding one or more splices on one or more customer drop cables; and a plurality of second holder slots formed in or attached to said second bulkhead and facing said second area for holding one or more splices on one or more distribution cables.

Moreover, these and other objects may be accomplished by a fiber optic cable splice enclosure comprising: a first access door attached to said enclosure and having a closed condition and an open condition which provides access to a first area within said enclosure for housing at least one fiber optic customer drop cable; a second access door attached to said enclosure and having a closed condition and an open condition which provides access to a second area within said enclosure for housing at least one fiber optic distribution cable, wherein said second area is manually inaccessible from said first area, wherein said first access door forms a first side of said enclosure, and wherein said second access door forms a second and opposite side of said enclosure; a plurality of fiber optic couplers located within said first area for receiving terminals of customer drop cables; a splitter residing within a portion of said enclosure, said splitter including a fiber optic input and a plurality of fiber optic outputs, several of said plurality of fiber optic outputs being respectively coupled to individual couplers of said plurality of fiber optic couplers, wherein said splitter is located outside of said first area of said enclosure; and a third side of said enclosure forming a cable entrance and exit side for passage of one or more customer drop cables and one more distribution cables.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Broken lines illustrate optional features or operations unless specified otherwise.

FIGS. 1-3illustrate a fiber optic cable splice enclosure1, in accordance with the present invention. The enclosure1includes a top side3, a right side5, a left side7, and a bottom side9. A first access door11is connected to the enclosure1and forms a front or first side of the enclosure1. A second access door13is connected to the enclosure1and forms a back or second side of the enclosure1, opposite to the first side of the enclosure1.

FIG. 2is a bottom view of the enclosure1. As best seen inFIG. 2, the first access door11is generally formed as a panel having one side edge15connected to the left side7of the enclosure1by at least one hinge17. An opposite side edge19of the first access door11includes first through third through holes21′,21″ and21′″.

The first access door11has a closed condition and an open condition. When the first access door11is in the closed condition, the first through third through holes21′,21″ and21′″ align with first through third threaded bosses23′,23″ and23′″ attached to, or integrally formed with, the right side5of the enclosure1, such that a respective screw or bolt (or a specialty fastener, such as a tamper resistant torx head screw) may be passed through the aligned first through third through holes21′,21″ and21′″ and engaged within the threaded bosses23′,23″ and23′″ to secure the first access door11in the closed condition. Preferably, the door includes a gasket which seals the first access door11when the first access door11is in the closed condition. When the first access door11is in the open condition, access is provided to a first area within the enclosure1, as will be discussed below.

The second access door13is generally formed as a panel having one side edge25also connected to the left side7of the enclosure1by at least one hinge27. An opposite side edge29of the second access door13includes fourth through sixth through holes31′,31″ and31′″.

The second access door13has a closed condition and an open condition. When the second access door13is in the closed condition, the fourth through sixth through holes31′,31″ and31′″ align with the first through third threaded bosses23′,23″ and23′″ attached to, or integrally formed with, the right side5of the enclosure1, such that a respective screw or bolt may be passed through the aligned fourth through sixth through holes31′,31″ and31′″ and engaged within the threaded bosses23′,23″ and23′″ to secure the second access door13in the closed condition. When the second access door13is in the open condition, access is provided to a second area within the enclosure1, as will be discussed below.

Although the first and second access doors11and13have been illustrated as being attached to the enclosure1by hinges17and27, it is envisioned that one or both of the first and second access doors11and13could be attached to the enclosure1by other types of mechanisms. For example, the hinges17and27may be replaced by tabs attached to, or integrally formed with, the first access door11. The tabs pass through and partially overlap edges of slots formed in the left side7of the enclosure1. When the first access door11is attached to the enclosure1by the illustrated hinges17and27or by the tabs and slots, the first access door11may optionally be completely removed from the enclosure1once the screws are removed from the first through third through holes21′,21″ and21′″ and the door is pivoted to a fully open position. Of course the second access door13may be similarly attached to the enclosure1.

The top side3of the enclosure1includes first and second looped portions39and41attached thereto, or integrally formed therewith. The left side7includes third and fourth looped portions39A and41A. The right side5includes fifth and sixth looped portions39B and41B. The first through sixth looped portions39,41,39A,41A,39B and41B may be used to secure the enclosure1to a field fixture during use.

FIG. 4illustrates one situation wherein the first and second looped portions39and41are employed. A first plastic zip or cable tie43is passed through the first looped portion39and also passed through a perforation in a first perforated angle iron47. A second cable tie45is passed though the second looped portion41and another perforation in the first perforated angle iron47. Hence, the enclosure1is securely fastened to the first perforated angle iron47.

The first perforated angle iron47may be secured to a second perforated angle iron49by one or more fasteners51. The second perforated angle iron49may be attached to the side of an aerial pole in the case of an aerial mounting of the enclosure1. Alternatively, an end53of the second perforated angle iron49may be embedded in concrete or dirt when the enclosure1is to be mounted inside of a weather resistant ground enclosure, as located near a street and lot line. In other words, a second metal or plastic enclosure would cover the enclosure1and angle irons47and49so as to make a more presentable and orderly appearance and provide additional protection. Of course, the third and fourth looped portions39A and41A or the fifth and sixth looped portions39B and41B could be used to mount the enclosure1in a horizontal orientation, as opposed to the illustrated vertical orientation. Also, the second perforated angle iron49could be eliminated and the first perforated angle iron47could be directly attached to a mounting structure. Of course, there are other types of mounting fixtures besides perforated angle irons which could be employed. A particular advantage to using the fifth and sixth looped portions39B and41B to mount the enclosure1in a horizontal orientation is that once opened, the first and/or second access doors11and13would be held open by gravity. By this arrangement, a technician would not need to expend effort to hold the first and/or second access doors11and13open.

Turning again toFIG. 2, the bottom side9of the enclosure1will be described in more detail. The bottom side9includes ports for the entry and exit of fiber optic cables. A first portion in the bottom side9includes a plurality of large ports57for receiving a plurality of distribution cables. The ports57may be constructed of a gasket material (e.g. rubber or foam). The gasket material presents a slight resistance to passage of a distribution cable through a port57therein, which results in a moisture and contamination resistant enclosure1.

Each port57may optionally include a plurality of precut rings. The gasket material within one or more of the precut rings may be removed so as to size the port57to the diameter of an entering or exiting distribution cable. By this manner, it would also be possible to size one of the ports57to receive any size distribution cable, or even a smaller sized drop cable. In the illustration ofFIG. 2, the leftmost and rightmost bottom ports are sized to receive a distribution cable, and the next to the rightmost bottom port57is sized to receive a drop cable.

The bottom side9also includes a second portion which includes a plurality of small ports61for receiving a plurality of customer drop cables. The ports61may be constructed of a gasket material (e.g. rubber or foam). The gasket material presents a slight resistance to passage of a smaller diameter customer drop cable through a port61therein, which results in a moisture and contamination resistant enclosure1. In the illustration ofFIG. 2, the two rightmost top ports61have been sized to receive larger diameter cables to illustrate the flexibility provided to the installer. Precut rings within the gasket material could also be present within the ports61.

FIG. 5is a perspective view of the enclosure1with the first access door11removed to provide access to the first area within the enclosure1.FIG. 5also illustrates outgoing customer drop cables70, an incoming distribution cable72and an outgoing distribution cable72′.

The customer drop cables70enter the bottom side9of the enclosure via the ports61. In the embodiment ofFIG. 5, each customer drop cable70is a jacketed cable including a strength member74(such as a metallic wire or fiberglass wire) and a jacketed fiber optic cable76having a connector or terminal78at the end of the jacketed fiber optic cable76.

After entering the enclosure1, each customer drop cable70is secured by a cable tie68. The cable tie68wraps around the customer drop cable70and through loop holes formed within the enclosure1so as to secure the customer drop cable70to the enclosure1. The strength members74are immediately connected to a ground bar71located proximate the entrance of the customer drop cables70. Some cables, such as all dielectric cable designs, include strength members74formed of fiberglass, and such fiberglass strength member74would also be connected to the ground bar71. Some cables are of an armor design. For an armored cable, the armor would be exposed, flattened and punched down onto a stud which would tie into the ground bar71or ground plate71P by a screw (seeFIG. 10). By such an arrangement, the armor of the cable could be mechanically and/or electrically connected to the ground bar71or ground plate71P.

The jacketed fiber optic cables76pass by entrance guides73and into loop guides75. The entrance guides73and loop guides75are mounted to a first bulkhead79, which defines a back of the first area within the enclosure1. The loop guides75ensure that a bend of the jacketed fiber optic cables76remains greater than a recommended minimum bend radius for the jacketed fiber optic cables76and accommodate the storage of any slack in the jacketed fiber optic cables76. Tabs75A are provided at the top ends of the loop guides75to keep the jacketed fiber optic cables76inside the loop guides75. After leaving the loop guides75, the terminals78at the ends of the jacketed fiber optic cables76are plugged into respective ones of couplers77. The term “coupler” is intended to be a broad term encompassing any device adapted to receive a fiber optic cable's termination, including bulkhead adaptors.

The couplers77are mounted to the first bulkhead79. Having the couplers77mounted to the first bulkhead79allows a technician to easily remove any or all of the terminals78and to clean the terminals78and/or couplers77without exposing equipment behind the first bulkhead79, as will be discussed hereinafter. Preferably, the couplers77are mounted at an acute angle to a plane of the first bulkhead79, such as at an angle of about 30 to 45 degrees. Therefore, the couplers77receive the terminals78at an acute angle relative to the plane of said first bulkhead79in order to preserve the minimum bend radius constraints of the jacketed fiber optic cables76. AlthoughFIG. 5illustrates eight couplers77, more or fewer couplers may be included on the first bulkhead79, such as four couplers77or sixteen couplers77.

FIG. 6is a perspective view similar toFIG. 5, but illustrates the use of alternative customer drop cables70′. The alternative customer drop cables70′ are very similar to the customer drop cables70which included a factory terminated connector at the end. However, the alternative customer drop cables70′ do not include a factory terminated connector; rather, a connector is spliced on in the field during the installation process. The actual cable portion of the two cable customer drop cable designs70and70′ may otherwise be identical. The alternative customer drop cables70′ enter the bottom side9of the enclosure via the ports61. In the embodiment ofFIG. 6, each alternative customer drop cable70′ is a jacketed cable including a strength member74and a buffered optical fiber80. The buffered optical fiber optical80has no terminal78at its end. An installation technician must splice on an extra buffered optical fiber82having a terminal84at its end to each of the buffered optical fibers80.

Each splice is protected by a splice sleeve86. The first bulkhead79includes a plurality of holder slots81attached thereto or integrally formed therewith. The holder slots81are sized to snugly receive the splice sleeve86therein and two or more splice sleeves86may be stacked into each holder slot81.

By the above arrangement, the enclosure1may accommodate either pre-terminated customer drop cables70′ or non-terminated customer drop cables70′ requiring splicing or combinations of the two types of customer drop cables70and70′. This is particularly advantageous as some customers demand the pre-terminated type of cables70, while other customers demand the non-terminated type cables70′.

FIG. 7is a back view of the enclosure1with the second access door13removed to expose a second area within the enclosure. The second area is manually inaccessible from the first area. The incoming distribution cable72in the illustrated embodiment ofFIG. 7includes eight fiber optic cables94. The incoming distribution cable72may be secured to the enclosure1by a cable tie91passing through holes93formed in a second bulkhead89and which are provided near the entrance port57for the incoming distribution cable72. If the incoming distribution cable72includes a strength member, the strength member may be attached to a grounding bar71A provided in the second area, in an identical manner as illustrated with regard to the ground bar71inFIG. 5. Of course, other types of cables can be terminated to the ground bar71, such as armored cables, all dielectric cables, and well as other types of known cables.

The outgoing distribution cable72′ in the illustrated embodiment includes the same eight fiber optic cables94. The outgoing distribution cable72′ may also be secured to the enclosure1by a cable tie (not illustrated) passing through holes93provided near the exit port57for the outgoing distribution cable72′. If the outgoing distribution cable72′ includes a strength member, the strength member may also be attached to the grounding bar71A in the second area.

Next, the manner by which the distribution cable installer forms the configuration illustrated inFIG. 7will be described. Several feet of jacket is carefully removed from the distribution cable72to expose the inner eight fiber optic cables94from a first jacket edge90to a second jacket edge92. The distribution cable installer inserts the incoming distribution cable72through an open slot95communicated to a port57and into the port57such that the first jacket edge90is located within the enclosure1and a few inches from the port57. The incoming distribution cable72is held in the port57and prevented from leaving the open slot95slot by the cable tie91.

The eight exposed fiber optic cables94are routed behind top tabs97A and through loop guides97, attached to or integrally formed with the second bulkhead89, which neatly organize the cable slack and ensure that a minimum bend radius is not exceeded. Entrance guides, as shown inFIG. 5, may also be included in the second area to guide the fiber optic cables94to the loop guides97. Although eight fiber optic cables94are illustrated, the distribution cable72could have more or fewer than eight fiber optic cables, such as twelve fiber optic cables. Next, the distribution cable installer inserts the outgoing distribution cable72′ through an open slot99and into another port57such that the second jacket edge92is located within the enclosure1and a few inches from the port57. At this point in the installation process the functionality of the distribution cable70has not been altered, e.g., none of the eight fiber optic cables94have been cut or spliced.

Next, the distribution cable installer removes one cable of the eight fiber optic cables94from the guides97and cuts the selected fiber optic cable. The incoming portion100of the selected fiber optic cable, which extends from the incoming distribution cable72, is spliced to a first preexisting fiber optic cable103which passes through the guides97and into a first opening105formed in the second bulkhead89. The outgoing portion102of the selected fiber optic cable, which extends into the outgoing distribution cable72′, is spliced to a second preexisting fiber optic cable107which passes through the guides97and into a second opening109formed in the second bulkhead89.

The splice between the incoming portion100and the first preexisting fiber optic cable103is covered by a first splice sleeve104. The splice between the outgoing portion102and the second preexisting fiber optic cable107is covered by a second splice sleeve106. The first and second splice sleeves104and106are held within a first set of holder slots101attached to or integrally formed with the second bulkhead89. The second bulkhead89also includes a second set of holder slots111, which are unused in the embodiment illustrated inFIG. 7.

Between the first bulkhead79(FIG. 5) and the second bulkhead89(FIG. 7) there resides a third area. The third area is separated from the first area by the first bulkhead79and is separated from the second area by the second bulkhead89. The third area houses a splitter113, as illustrated inFIG. 8.

The splitter113has one input103(which is the same element as the first preexisting fiber optic cable103) and nine outputs which are spliced to the one input103. One output of the nine outputs is the second preexisting fiber optic cable107. The remaining eight outputs of the nine outputs are connected to respective ones of the eight couplers77attached to the first bulkhead79. By this arrangement, the incoming portion100of the selected fiber optic cable is spliced to the outgoing portion102of the selected fiber optic cable and also to each of the eight couplers77in the first area of the enclosure1. A first fastener feature115and a second fastener feature117(such as screws, tabs or clips) are attached to the splitter113.

The splitter113is a commercially available part. Therefore, structural details of the splitter113will not be described in greater detail. The term “splitter” as used herein is a broad term and is meant to encompass any device which receives an optical input signal and provides multiple optical output signals (e.g. 2, 3, 4, 8, 16 output signals) based upon the received input signal. A splitter may be a symmetrical or nonsymmetrical device, wherein one of the output signals has more signal strength than another of the output signals of the splitter. The splitter may be a passive or active device, e.g., powered or non-powered. Again, such splitters are known in the art and reference may be made to prior patents for the internal configuration of such “splitter” devices.

FIG. 9is a partial cutaway view of the front of the enclosure1with the first access door11and the first bulkhead79removed to illustrate the connections between the splitter113and the couplers77.FIG. 9also illustrates a first fastener119cooperating with the first fastener feature115and a second fastener121cooperating with the second fastener feature117to attach the splitter113to the second bulkhead89. Clips could be used to secure the splitter113to the second bulkhead instead of screws. It should be appreciated that fewer couplers77could be employed on the first bulkhead79. For example, four couplers77could be placed on the first bulkhead79, whereby the splitter113would have one input and five outputs. Also, more couplers77could be employed on the first bulkhead79. For example, sixteen couplers77could be placed on the first bulkhead79, whereby the splitter113would have one input and seventeen outputs.

FIG. 10is a back view of the enclosure1with the second access door13removed to expose the second area within the enclosure1in accordance with an alternative embodiment of the invention. Like elements have the same reference numerals as inFIG. 7. The incoming distribution cable72in the alternate embodiment ofFIG. 10includes eight fiber optic cables94; however, the outgoing distribution cable72′ with eight fiber optic cables (FIG. 7) has been replaced with two outgoing distribution cables130and131, each with four fiber optic cables.

Basically, the eight fiber optic cables94, which would have passed into a single outgoing distribution cable72′, have been spliced into the eight fiber optic cables122of the two smaller outgoing distribution cables130and131. The splices are protected by eight splice sleeves124. The holder slots111have a sufficient depth such that two or more splice sleeves124may be stacked into each holder slot. Hence, inFIG. 10, two of the six illustrated holder slots124are holding two stacked splice sleeves124. Therefore, the distribution installer can splice distribution cables inside of the enclosure1which improves the flexibility of the system and options available to the installer. Although eight total holder slots101and111are illustrated on the second bulkhead89, more holder slots may be included so that distribution cables with more fiber optic cables may be spliced within the enclosure1.

The second bulkhead89may be removably attached to the enclosure1via fasteners125, such as clips or screws. Therefore, the second bulkhead89may be moved relative to said enclosure1to access the splitter113. Alternatively, or in addition, the first bulkhead79could be removably attached to the enclosure1by similar fasteners in a same manner. In either event, a technician could gain access to the splitter113, by either removing a bulkhead79or89or tilting a bulkhead away from the enclosure so as to test, service and/or replace the splitter113.

FIG. 10also illustrates a preferred alternative design for the ground bar71A. The grounding bar71A ofFIG. 7has been replaced with a ground plate71P, which may be formed of sheet metal. The ground plate71P includes threaded holes71H which are sized to receive threaded capstan bosses71C, such as screws with oversized heads. The capstan bosses71C could be formed of metal, but are more preferably formed of plastic. As illustrated inFIG. 10, the strength members74of incoming and outgoing cables72,130and131are captured by friction between the capstan bosses and the ground plate71P. If a strength member74is metallic it can be effectively grounded to the ground plate71P. Also, if a cable, such as cable131includes an armor layer132, the armor layer132may be pulled back, flattened and screwed to the ground plate71P with a screw133. In a preferred embodiment, the ground bar71ofFIGS. 5 and 6could also be replaced by a sheet metal ground plate and capstan bosses, as illustrated inFIG. 10.