Optical fiber slack storage tray for distribution cabinet

[0001] The present invention relates to apparatus and methods for termination and storage of optical fiber cables, such as distribution cables.

[0002] With respect to termination and storage of optical fibers including distribution fibers, various concerns exist. One concern is providing high density to minimize needed space. In the case of outside plant enclosures, a reduced size for the enclosures and the internal structures is preferred.

[0003] A further concern related to termination and storage of optical fiber cables is the ease of access to the cables and the terminations. Such ease of use is desired during assembly, during installation in the field, and later when changes or modifications to the system are desired requiring adding or removing terminations, or when cleaning and checking the terminations.

[0004] A further concern in the area of termination and storage of optical fiber cables includes protecting the optical fiber from damage from excess bending below the minimum bend radius of the cable. Such protection of the fibers is desired during assembly and installation, and later when individual terminations and cables are accessed for cleaning or modification.

[0005] Further improvements in these areas are desired.

[0006] One aspect of the present invention relates to a cable storage tray including a base and a hinged cover. The base receives a loop of optical fiber cables between inner and outer walls. The optical fiber cables further communicate with a cable pathway on the cover with the optical fiber cables positioned between inner and outer walls of the cable pathway. The cable storage tray protects a slack length of cable. Cable retention tabs are preferably provided to retain the cables in the cable pathways.

[0007] A further aspect of the present invention relates to an apparatus and method including providing a plurality of slack storage trays mounted to a fixture. Each slack storage tray includes inner and outer walls extending from a bottom wall for holding multiple loops of optical fiber cables. The cables are wound around the inner wall about an axis perpendicular to the bottom wall. The fixture further includes a plurality of cable terminations in a cable termination area. The cable termination area is preferably defined by a plurality of rows of adapters. The rows are preferably slidable relative to the slack storage trays. Cables are terminated in the cable termination area. Slack associated with the cables is stored in the slack storage trays.

[0008] A method is provided wherein loops of cable slack are stored in a storage tray that allows the cable slack to be pulled from the storage tray at a selected time, and then later received by the storage tray when the slack is no longer needed. One preferred method includes providing a two level storage tray where a first portion of the slack is looped around a cable radius limiter on a first level of the tray, and a second portion of the slack is positioned around a cable radius limiter on a second level of the tray. The preferred method also includes providing a moveable cover to close access to the first level, and wherein the cover defines the cable radius limiter of the second level.

[0021] Referring now to FIGS. 1–4, one embodiment of an optical fiber distribution cabinet 10 is shown. Cabinet 10 may also be referred to as an enclosure 10, such as an outside plant enclosure. Enclosure 10 receives feeder cables and provides connection points for connecting to distribution cables to connect the feeder cables to equipment connected to the distribution cables. Enclosure 10 provides a secure and weather-resistant structure around the internal components.

[0022] Enclosure 10 includes a housing 12 defining an interior 14 for receiving the cabling and the terminations. Cables enter enclosure 10 at opening 30, and cables exit at opening 31. Pivoting doors 16 provide front access to housing 12 and are pivoted about hinges 18. Disposed within interior 14 is an enclosure subunit or fixture 20 including various cable management structures. Interior 14 also includes splitters 24 for splitting the feeder cable into individual cables. Vertical cable guides 26 and cable radius limiters 28 help manage the cabling.

[0023] The individual cables from splitters 24 are terminated in termination area 38, which includes a plurality of adapters 40. Cable manager 34 manages the individual cables (not shown) extending to a front side 38a of termination area 38. On a back side 38b of termination area 38 are a plurality of cables 78 defining the distribution cables (see FIG. 11). The distribution cables are managed by a fiber storage area 42 including a plurality of fiber storage trays 44.

[0024] Referring now specifically to FIGS. 3, 4, and 11, cable manager 34, termination area 38, and fiber storage area 42 are shown in greater detail. In the illustrated embodiment, cable manager 34 and termination area 38 are mounted to a side wall 50 of fixture 20. Fiber storage trays 44 are mounted to a back wall 52 of fixture 20, behind termination area 38.

[0025] Cable manager 34 includes a plurality of curved cable guides 56 for directing the cables in a downward direction from termination area 38. At an end of cable guide 56, one of cable retention fingers 58, 59 are provided. Cable manager 34 includes sections 60, 61, 62 with staggered guides 56. In section 60, guides 56 project outward the furthest from back wall 52. In section 62, guides 56 project the least. In section 61, guides 56 project an intermediate amount. Such a construction helps avoid too many cables in any vertical space. Outer bars 63 of cable manager 34 further help retain the cables extending to termination area 38.

[0026] Adapters 40 in termination area 38 are mounted on movable slides 64, which slide relative to mounting members 66. Mounting members 66 extend from side wall 50. Slides 64 are selectively movable along a longitudinal axis 70 so as to move a selected row 72 of adapters 40. In the moved position, each adapter 40 and the associated connecters are more easily accessible to a technician needing to connect or disconnect the cable and an adapter, or to clean one of the connecters. In the moved position, both the front and the back of each adapter 40 are more accessible. In FIG. 11, top slide 64 is moved to the access position. Lever 74 helps control movement of each slide 64. Slides 64 and mounting members 66 are described in greater detail in U.S. Pat. No. 6,591,051, the disclosure of which is incorporated herein by reference. In FIGS. 1–4, only one adapter 40 is shown in each slide 64. Five more adapters 40 fit into each slide 64 shown. Also, it is noted that axis 70 is disposed at angle not at 90 degrees relative to side wall 50. Slides 64 pull slightly toward a front of enclosure 10.

[0027] In the illustrated embodiment, slides 64 move horizontally along each longitudinal axis 70. Feeder cables (not shown), also referred to as splitter output cables, extend from splitters 24, through cable guides 26 and/or slack storage 28, to cable manger 34. From cable manager 34, the cables with end connectors mate with one of adapters 40 on front side 38a. Adapters 40 in the illustrated embodiment are shown with removable dust protector plugs 76 in each adapter.

[0028] Still referring to FIGS. 3 and 11, the distribution cables 78 extending from adapters 40 on slides 64 are managed by fiber storage trays 44. Each fiber storage tray 44 allows for management of slack associated with each cable 78. Such slack includes slack for manufacturing tolerances for cables 78. Fiber storage tray 44 also allows for management of additional slack, such as the slack needed to avoid excessive pulling on the cable when cable 78 and its terminating connector are removed from adapter 40 and cleaned by the technician. Further, slack may also be desirable to allow for ease of movement of slides 64. Fiber storage tray 44 manages the slack in an organized manner to avoid excessive pulling on cables 78 to prevent damage.

[0029] Now referring to FIGS. 5 through 10, fiber storage tray 44 includes a base 120 and a cover 164 hinged to base 120 along hinge axis 152. Cover 164 hinges for movement to an open position to allow access to a first side 121 of base 120. Cover 164 hinges closed to limit access to side 121, and help protect cables stored on base 120.

[0030] Base 120 includes a bottom wall 122, generally planar, with an upstanding outside wall 124. Upstanding outside wall 124 defines a cable entry location 126 for cables entering tray 44. Cable entry location 126 is located adjacent a side 46 of tray 44.

[0031] In the illustrated embodiment, adjacent cable entry location 126 is a fan out holder 128 for holding one or more cable fan outs 130. Fan outs 130 are held between end tabs 132 and 134 of base 120.

[0032] Base 120 further includes an inner radius 138 limiter defined by an inner wall 144 extending from bottom wall 122. Inner wall 144 defines a surface for looping the cables generally about an axis 148 perpendicular to bottom wall 122. Various cable retention tabs 140 project from upstanding outside wall 124 and inner wall 144 to further define a cable path 142. Cabling within tray 44 can be wound or looped one or more times around inner radius limiter 138. The cabling generally stays in position around inner radius limiter 138 within cable path 142 by retention tabs 140.

[0033] Base 120 includes hinge pins 146 for cooperating with hinge plates 180 of cover 164. When cover 164 is in the hinged open position as shown in FIGS. 6 and 7, the cabling can be positioned in cable path 142, or removed, if necessary. When cover 164 is placed in the closed position as shown in FIG. 5, the cabling is further secured within cable path 142 by cover 164. The cabling exits base 120 and communicates with features on a first side 165 of cover 164 by passing through a cable entry location 166. When cover 164 is closed, fan outs 130 are retained in base 120.

[0034] Cover 164 includes a bottom wall 168, generally planar. An upstanding outside wall 170 extends upward from bottom wall 168. An inner radius limiter 172 includes an upstanding inner wall 173. A cable path 176 is defined between upstanding outside wall 170 and inner wall 173. Cable retention tabs 174 extend from outside wall 170 and inner wall 173. Inner wall 173 defines a surface for wrapping the cables generally about an axis 178 perpendicular to bottom wall 168. Cable retention tabs 174 further help retain cabling extending from cable entry location 166 through cable path 176 to an exit location 188. Exit location 188 is generally at a front 190 of tray 44. From cable exit location 188, the cabling including the end connectors mate with adapters 40 on back side 38b of termination area 38.

[0035] Base 120 includes a latch groove 160 for receipt of a latch tab 184 of cover 164 to maintain the cover and base in the closed positions.

[0036] Base 120 includes projections 154 along a back 150 of tray 44 for mating with slots 86 in back wall 52 of fixture 20. Slots 86 narrow to fit into the necked regions 156 of projections 154 as trays 44 are slid to the left side of fixture 20. Spring arm 158 is biased against back wall and is also received in slot 86. To remove a tray 44, a gripping tab 162 is provided along a side of tray 44. Tray 44 is slid to the right in order to remove spring arm 158 from the received slot 86 and to position projections 154 in the wide portion in each of slots 86 in order to remove the tray from back wall 52.

[0037] During use of tray 44, cable 78 from fan out 130 is loosely wound around inner radius limiter 138 of base 120 (see dashed lines in FIG. 7) and passed through cable entry location 166. Cover 164 is closed retaining the cable and any fan outs 130 in a first compartment of tray 44. The cable is then positioned around inner radius limiter 172 of cover 164 around to exit 188. The cables 78 extend to adapters 40 at back side 38b of termination area 38. When the slack in cable 78 is pulled relative to storage tray 44, the inner radius limiters 138, 172 prevent cable 78 from going below the minimum bend radius. When the cable is pushed back into storage tray 44, the slack is contained by tray 44 including the outside walls 124, 170, cable retention tabs 140, 174 and cover 164 positioned over base 120. The other end of the cabling managed by tray 44 passes out through cable entry location 126, and can be tied at tie off locations 90 of fixture 20. Fan outs 130 allow for multiple individual fibers to be combined into a single jacketed cable. These jacketed cables can exit enclosure 10 at exit 31.

[0038] The adapters 40 are arranged in horizontal rows, with the connector axes 46 extending in a horizontal plane, generally coplanar with trays 44. In this manner, the loops of slack for each connector on back side 38b are managed and protected.

[0039] Referring now to FIG. 11, a modified tray base 192 includes a splicing area 194 including a splice holder 196. Inner radius limiter 138 includes gaps 198 for allowing cables to enter and have access to splice area 194.

[0040] The splitters 24 can be of conventional designs. The splitters 24 shown in the preferred embodiment are described in further detail in copending application Ser. No. 10/980,978, filed Nov. 3, 2004, entitled FIBER OPTIC MODULE AND SYSTEM INCLUDING REAR CONNECTORS, the disclosure of which is herby incorporated by reference. Other equipment besides splitters 24 can be used in cabinet 10, if desired. Cable clamps 25 on fixture 20 are used for clamping of the feeder cables extending toward splitters 24.

[0041] In FIGS. 1 and 2, a connector storage area 200, or connector parking lot, is provided. The connector parking lot can be used to store the connectors and cables extending from splitters 24 until connection at front side 38a of termination area 38 is desired.

[0042] Various connector and adapter styles can be used. In the illustrated embodiment, SC type are shown. Other styles such as ST, FC, LX.5 (by ADC Telecommunications, Inc., such as in U.S. Pat. No. 6,142,676) and LC can be used.

[0043] The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.