Abstract:
A fiber cable adapter comprises adjacent rows of fibers, each beginning with a set of fibers comprising a fiber pair, which comprises a transmitting fiber adjacent a receiving fiber, and a spare fiber adjacent the fiber pair. The spare fiber immediately precedes the fiber pair in one of the rows and immediately proceeds the fiber pair in the other row. A fiber cable cassette comprises an adapter panel supporting the fiber cable adapter. An integrated fiber cable management system comprises a fitting having a body with a collet through which a cable passes. A lock nut is threaded on a first end of the body to hold the body in relation to a chassis. A sealing nut is threaded on a second end of the body to tighten the collet on the cable to hold the cable in place in relation to the chassis. A flexible protector extends from the sealing nut to control the bend of the cable between the chassis and a fiber cable cassette. The flexible protector restricts the bend of the cable and thus extends the life of the cable.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/025,468 filed Feb. 1, 2008, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The invention relates generally to optical communications and more particularly to fiber optic cables and connections used for connecting electronic equipment used in the transmission of digital and analog data. 
         [0003]    In the field of data communications, fiber optic cables have surpassed electric cables because of their enormous bandwidth capabilities. As technology grows and more demands are being placed on data transfer, the need for higher bandwidth and more connections is growing. Additionally, while demand for more bandwidth and more connections grows, the cost for space allocated to data communications increases, creating a clash between adding more connections and cost. 
         [0004]    Fiber optic cables used in data communications are terminated at each end with connectors that plug into various pieces of electrical equipment. These cables are usually not run continuously from one terminus to another, but connect to other cables through a chassis that house cassettes for mating with fiber optic cable connectors. 
         [0005]    Fiber optic cables typically have either a loose construction or a ribbon construction. Fiber optic cables with loose construction contain separate fibers in bundles within a cable following a standard color pattern. In known solutions, fibers are terminated individually and mated to other similarly terminated fibers to complete the connection. Ribbon fiber optic cables are constructed of the same loose colorized fibers as round cables but are laid in a planar array following the same standard color pattern. They are then coated with a common layer and irradiated with a UV light source that cures them in that common layer. 
         [0006]    Round or ribbon cable fibers are terminated either with a breakout that separates the fibers for individual conventional connectors, such as ST, SC, LC, and MU connectors, or with multi-fiber connectors, such as MPO (multi-fiber push on) connectors. One very successful MPO connector is a MTP® brand connector, which is a mechanical transfer pull off connector manufactured and sold by US CONEC LTD of Hickory, N.C. 
         [0007]    In known fiber optic communication systems, a fiber optic cable is typically terminated in groups of 12 fibers or less to connectors of the same strand count. In multi-fiber connectors, there is a problem with light separation between fibers at high bit-rate transmission levels (e.g., beyond ten Gigabit per second (10 GB/S)). Lack of adequate light separation results in crosstalk, which reduces the efficiency and effectiveness of the fiber optic connection. Crosstalk causes, among other problems, bit error and data corruption. As a result, repeated signal transmission is required. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention relates to a fiber cable adapter comprising adjacent rows of fibers. Each row begins with a set of fibers comprising a fiber pair, which comprises a transmitting fiber adjacent a receiving fiber, and a spare fiber adjacent the fiber pair. The spare fiber immediately precedes the fiber pair in one of the rows and immediately proceeds the fiber pair in the other row. The invention also relates to a fiber cable cassette comprising an adapter panel supporting a fiber cable adapter according to the present invention. 
         [0009]    The present invention further relates to a fiber optic communication system. The system comprises a chassis. A cassette is housed within the chassis. The cassette has a fiber cable adapter. A fiber cable comprises a fiber optic connector connected to the fiber cable adapter. An integrated fiber cable management system comprises a fitting having a body with a collet through which the cable passes. A lock nut is threaded on a first end of the body to hold the body in relation to the chassis. A sealing nut is threaded on a second end of the body to tighten the collet on the cable to hold the cable in place in relation to the chassis. A flexible protector extends from the sealing nut to control the bend of the cable between the chassis and the cassette. The flexible protector restricts the bend of the cable and thus extends the life of the cable. 
         [0010]    Various advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention will be appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
           [0012]      FIG. 1  is a top plan view of an exemplary high-density fiber optic communication system. 
           [0013]      FIG. 2  is a partially exploded front perspective view of an exemplary chassis of the high-density fiber optic communication system shown in  FIG. 1 . 
           [0014]      FIG. 3  is a front perspective view of an exemplary cassette of the high-density fiber optic communication system shown in  FIG. 1 . 
           [0015]      FIG. 4  is a diagrammatical view of an exemplary fiber optic cable showing elements that allow a high-density connection. 
           [0016]      FIG. 5  is a diagrammatical view of another exemplary fiber optic cable showing elements that allow a high-density connection. 
           [0017]      FIG. 6  is a cross-section of two fiber optic cable legs jacketed together to produce a shotgun style construction fiber optic cable, wherein each leg includes 72 fibers. 
           [0018]      FIG. 7  is a cross-section of a fiber optic cable leg that includes 48 fibers. 
           [0019]      FIG. 8  is a schematic view of a high-density fiber optic cable showing multi-fiber connectors. 
           [0020]      FIG. 9  is a diagrammatical view of a 24-fiber connector pattern. 
           [0021]      FIG. 10  is a diagrammatical view of a 48-fiber connector pattern. 
           [0022]      FIG. 11  is a diagrammatical view of a 72-fiber connector pattern. 
           [0023]      FIG. 12  is an exploded, side elevational view of an exemplary integrated cable management system including a fitting integral with a cable, wherein the fitting include a flexible protector that controls the bend of the cable. 
           [0024]      FIG. 13  is an end view of the fitting shown in  FIG. 12  cooperating with a portion of the chassis shown in  FIG. 1 . 
           [0025]      FIG. 14  is a top plan view of the fitting holding a fiber optic cable in position in relation to the chassis and a cassette, wherein the chassis has a panel removed. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]    Detailed reference will now be made to the drawings in which examples embodying the present invention are shown. The detailed description uses words and phrases as identifiers on the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. The following description is merely exemplary in nature and is not intended to limit the present invention, or its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0027]    As shown generally in  FIG. 1 , a high-density fiber optic communication system  110  generally comprising a fiber chassis  112 , cassettes  114  housed within the chassis  112 , and a high-density fiber optic cable  30  connected to the cassette  114  via connectors, all of which will be described in further detail in the description that follows. 
         [0028]    An exemplary chassis  112  is shown in  FIG. 2 . The chassis  112  may take on any suitable form, including, for example, a 4U rack mount chassis. The chassis  112  may comprise a housing  120 , which may be metal or some other suitable construction. The housing  120  may have a removable panel  122  to permit ease of access within the housing  120 . The removable panel  122  may have a hinged portion  124  that provides limited access within the housing  120 . The housing  120  may further have a locking front  126 , as show in the drawings, to permit access to cassettes  114  therein. The housing  120  may be provided with brackets  128 , or other suitable structure, removable or non-removable, for the passage and, if desired, support of the high-density fiber optical cables  30 . The brackets  128  may be located along the sides, back and top of the housing  120 , or located in a suitable location. The brackets  128  may be configured to support an integrated cable management system  140 , which will be described in further detail with reference to  FIGS. 12-14  in the description that follows. The housing  120  may house a plurality of slots, or other structure, sufficient for receiving cassettes  114 . In the illustrated embodiment,  12  slots are provided, each for receiving a cassette, although fewer or more slots may be provided. The chassis  112  is structured and dimensioned to be supported by a rack (not shown), which is structured and dimensioned to support a plurality of chassis, such as in a vertically stackable manner. In addition to housing high-density fiber optic cassettes  114 , the chassis  112  may house adapter panels, CAT5E cassettes, media converters, as well as other data communication components. 
         [0029]    The high-density fiber optic cassettes  114  housed within the chassis  112  may take on any suitable form. As shown in  FIG. 3 , the high-density fiber optic cassettes  114  may be comprised of a housing  132 , which may be metal or some other suitable construction. The housing  132  may have a removable panel  134  to permit ease of access within the housing  132 . The housing  132  may be provided with fiber adaptor panels  136 , or other suitable structure, removable or non-removable, which support adapters  138 , which may be connected to the high-density fiber optical cables  30 . Each brand high-density fiber optic cassette may support 24 or more fibers. The number of fibers supported depends on the fiber adaptor panel  136  employed, as will become apparent in the description that follows. The cassettes  114  may be supported in the chassis  112  in any suitable manner, including, for example, with push grommets supported in relation to adaptor panel portions extending from the sides of the cassettes  114 , wherein the push grommets may be pushed through holes (not shown) associated with respective slots and an insert may be pushed through the grommet. 
         [0030]    The high-density fiber optical cables  30  may include 24 fibers or more. As shown in  FIG. 4 , the cables  30  may terminate at a first pair of high-density fiber optic connectors  32  at a first end  34  and a series of subunit connectors  36  at a second end  38 . This first pair of high-capacity connectors  32  may include 24 to 72 fibers. The subunits may be terminated to 12-fiber connectors that follow a color code as set out in TIA/EIA 598 “Optical Fiber Color Coding.” The connectors may then be polished by commonly used craft equipment. 
         [0031]    As further shown in  FIG. 4 , a pair of break-out housings  40  may be located near the second end  38  and may be adapted to split a single high-density fiber optic cable  30  into individual fibers  42 , which may terminate in the series of subunit connectors  36 . It should be understood by those skilled in the art that the individual fibers  42  may be combined together and terminated together as necessary for certain applications, for example, when two individual fiber optic cables  42  that operate as a transmitting and receiving link to a piece of electronic equipment are housed in a common sleeve and terminated to a common subunit connector  36 . 
         [0032]    An example of another cable  30 ′ may include a 144-fiber brand backbone harness. The 144-fiber brand backbone harness is shown in  FIG. 5 . The backbone harness may include two fiber legs jacketed together to produce a shotgun style construction, as shown in  FIG. 6 . Each leg may include 72 fibers. Alternatively, each a fiber leg may include 48 fibers, like the fiber leg show in  FIG. 7 , to form a 96-fiber brand backbone harness. The backbone harness may terminate at a first pair of high-density fiber optic connectors  32 ′ at a first end  34 ′ and a second pair of connectors  36 ′ at a second end  38 ′. 
         [0033]    It should be understood that, depending on the cable and connectors employed, the cassettes  114  may support, for example, 24, 48, 72, 96 and 144 fibers, or in the case of a feed through cassette, up to 864 fibers. Two 12 fiber-legs can form a 24-fiber cable. Two 24 fiber-legs can form a 48-fiber cable. Two 48 fiber-legs can form a 96-fiber cable. Two 72 fiber-legs can form a 144-fiber cable. It should further be understood that various combinations of cables can be used with various combinations of connectors, for example, 12 72-fiber connectors on both the front and back of the cassette  114  can be used to feed through 864 fibers (12 72-fiber cables). 
         [0034]    In  FIG. 8 , there is illustrated a high-density fiber optic cable  30  with multi-fiber connectors. The fiber optic cable  30  may have high-density fiber optic connectors  32 ,  36  at the first and second ends  34 ,  38  in a ribbon construction and the industry standard TIA/EIA 598 color coding mentioned above. It should be understood by those skilled in the art that this invention may be applicable for use with layouts of fiber optic cables and other styles of fiber optic connectors. 
         [0035]    It should be understood by those skilled in the art that multi-fiber optical cables may comprise pairs of fibers. Each pair may be generally designated by a mutual number and a distinct letter (1-a, 1-b, 2-a, 2-b, etc.). Pairs are often used because most electronic equipment that accepts fiber optic cable operates in a full-duplex mode that requires distinct transmitting and receiving fibers. Therefore, the pairing of fibers keeps the ends matched up with their respective transmitting and receiving channels. 
         [0036]    Continuing with reference to  FIG. 8 , an exemplary termination numbering scheme is shown for each end of the fiber optic cable  30  shown in  FIG. 4 . At the first end  34  (designated the “A” side), the termination scheme is “1-a, 1-b, 5-a, 2-a, 2-b, 5-b, 3-a, 3-b, -6-a, 4-a, 4-b, 6-b” on one of the first pair of high-density fiber optic connectors  32  and is “11-a, 7-a, 7-b, 11-b, 8-a, 8-b, 12-a, 9-a, 9-b, 12-b, 10-a, 10-b” on the other connector  32 . At the second end  38  (designated the “B” side), the termination schemes that match the color codes of the first end  34  are shown as “1-b, 1-a, 5-b, 2-b, 2-a, 5-a, 3-b, 3-a, 6-b, 4-b, 4-a, 6-a” and “11-b, 7-b, 7-a, 11-a, 8-b, 8-a, 23-b, 9-b, 9-a, 12-a, 10-b, 10-a.” 
         [0037]    A pattern of interspersing individual fibers between fiber pairs separates light paths between fibers in order to provide better optical performance with reduced crosstalk. In  FIG. 9 , an example of a 24-fiber optic cable with such a pattern is illustrated. In the example, transmitting fibers T and receiving fibers R are paired to form the transmitting and receiving fiber pairs that are separated by spare fibers S. A first 12 fibers thus has four transmitting and receiving fiber pairs and two spare fiber pairs, four spare fibers S in all, arranged so as to separate the four transmitting and receiving fiber pairs, as shown in the drawing. An adjacent second 12 fibers similarly have four transmitting and receiving fiber pairs but the transmitting and receiving fiber pairs are shifted by a spare fiber S in relation to the first 12 fibers so as to separate the transmitting fibers T of the first 12 fibers from adjacent transmitting fibers T of the second 12 fibers, and separate the receiving fibers R of the first 12 fibers from adjacent receiving fibers R of the second 12 fibers. This results in a diagonal separation between transmitting fibers T and a diagonal separation between receiving fibers R that is sufficient to reduce crosstalk caused by light transmitted between like fibers. 
         [0038]    The above described a pattern may be repeated. For example, a 48-fiber cable may have a pattern that is repeated, as illustrated in  FIG. 10 . A 72-fiber cable may similarly have a pattern that is repeated, as illustrated in  FIG. 11 . It should be understood that two 72-fiber optical cables, within a single trunk cable, having a 72-fiber connector may be optically connected to a cassette  114 , wherein  144  fibers may be distributed into six different 24-fiber cables, each terminating in a 24-fiber connector, such as the 24-fiber connector. A first end of a fiber optic cable may be optically connected to each of the 24-fiber connectors. A second end of the fiber optic cable may be terminated in each of the subunit connectors. Using the termination scheme, as described above, crosstalk problems traditionally associated with such high-density fiber optic cables can be avoided. As a result,  144  separate fiber connections can be established between two locations using only a single trunk cable with a cross section of only about 12 square centimeters. Additionally, 12 cassettes  114  can be arranged within a single chassis  112 , such as a 4U rack mount chassis, thus allowing 1728 individual fiber connections to be established while only occupying four units of rack mount space. 
         [0039]    In  FIG. 12 , there is illustrated an integrated cable management system, as mention above. The system, which is generally indicated at  140 , may comprise, among other features, a fitting  142  integral with a cable, such as the cable  30 ″ shown in  FIG. 5 . The fitting  142  may comprise a body  144  having a clearance hole  146  passing therethrough. An integral nut  148  may be located proximate the axial center of the body  144 . Threads  150 ,  152  (e.g., Acme or other suitable threads) may be provided on opposing sides to the integral nut  148 . A collet  153  may be provided to accommodate various size cables. A lock nut  154  may be threaded on the threads  150  at a first end  156  of the body  144  to hold the body  144  in fixed relation to the chassis  112 , as will become apparent in the description that follows. Acme threads may prevent skipping and speed up installation. A sealing nut  160 , with an integral flexible protector  162  extending therefrom, may be threaded on the threads  152  at a second end  164  of the body  144 . The flexible protector  162  may provide lazy bend protection for the cable  30 ″ to prevent sharp bends and extend the cable life. 
         [0040]    The fitting  142  may be fixed in relation to the chassis  112  via the brackets  128 . This may be done with any suitable structure. For example, as shown in  FIG. 13 , the brackets  128  may comprise one or more substantially T-shaped openings  166 . The opening  166  may extend to the edge of the bracket  128 . With the bracket  128  removed, the first end  156  of the body  144  may pass through a first leg  168  of the opening  166  and be guided in a second leg  170 . The second leg  170  may be perpendicular, transverse, or otherwise oriented in relation to the first leg  168 . The locking nut  154  may be tightened onto the first end  156  of the body  144  and against the bracket  128  so as to hold the body  144  in fixed relation to the bracket  128 . It should be noted that the first end  156  of the body  144  may face outwardly in relation to the bracket  128 , or in relation to the chassis  112 , when the bracket  128  is secured back in relation to the chassis  112 . 
         [0041]    With bracket  128  secured back in relation to the chassis  112 , the cable  30 ″ may be adjusted in relation to the body  144 , and the flexible protector  162 , by axially displacing the cable  30 ″ through the clearance hole  146 . The adjustment of the cable  30 ″ may include positioning the cable  30 ″ as desired, with a desired bend between the bracket  128  and the cassette  114 . Once in a desired position, the sealing nut  160  may be tightened against the collet  153 . In turn, the collet  153  tightens against the cable  30 ″ to hold the cable  30 ″ in the desired position, as shown, for example, in  FIG. 14 . The flexible protector  162  may prevent the cable  30 ″ from making a sharp bend. Although the flexible protector  162  is shown to have a helical construction, other constructions may be suitable. 
         [0042]    The advantages of the above described embodiments and improvements are readily apparent to one skilled in the art as enabling the efficient and effective transmission of data. Additional design considerations may be incorporated without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited by the particular embodiments or forms described above, but by the appended claims.