Distribution frame for telecommunications cable

Termination shelf for telecommunications cable with mounting positions for conductor connector devices. The mounting positions are accessible from one side of the shelf for insertion of the connector devices. Also a guide is provided to enable a flexible transmission element to be inserted into the tray from the same side as for shelf insertion, the guide being shaped to guide the transmission element towards a remote side of the frame and then to guide the tramsmission element in the opposite direction through the mounting position. Frontal loading of the connector devices and of incoming conductors is thereby a use feature with the termination shelf.

BACKGROUND OF THE INVENTION 
In the electrical telecommunications industry, an incoming 
telecommunications cable enters a customer's premises and the conductors 
of the incoming cable extend to a distribution frame where they are 
connected to telecommunications conductors of the customer's internal 
telecommunications network. The arrangement and design of a distribution 
frame is such that, for accessibility, the customer's conductors extend 
into the front of the frame and into connectors to be connected to the 
conductors of the incoming cable. Frontal access into the distribution 
frame is most important for the customer, not only for initial connection 
of conductors of his internal network, but also for removal and 
repositioning of his conductors to accommodate changes in his own network 
design accompanied by interchangeability with the incoming conductors at 
the terminals in the distribution frame. To allow for frontal access of 
customer's conductors, conductors of the incoming cable extend into the 
rear of the connectors in the distribution frame. It is conventional 
practice to pass the incoming conductors along the back or rear of the 
frame or down through the frame towards the rear. This positioning of the 
incoming conductors increases the difficulties in directing them each to 
its specific location for connection into a specific terminal. A typical 
distribution frame is described in U.S. Pat. No. 4,278,315, granted July 
14, 1981 in the name of B. T. Osborne. This patent shows the rear access 
of incoming conductors to a distribution frame. 
In the optical telecommunications field, distribution frames are not 
provided which connect, at one location, optical fibers of an incoming 
cable with optical fibers of a customer's internal network. 
SUMMARY OF THE INVENTION 
The present invention seeks to provide a termination shelf for optical 
fibers which in use lessens the above positioning problem for incoming 
conductors and which may be used both in the electrical and optical 
telecommunications fields. When used in the optical field, such shelves 
may be used separately from fiber termination frames or may be mounted 
upon or form a part of such frames. A fiber termination frame may be 
either a distribution frame for optical fibers or an equipment frame which 
carries electronic equipment and has at least one termination shelf for 
incoming optical fibers. 
Accordingly, the present invention provides a termination shelf for 
telecommunications cable comprising a first side and a second side remote 
from the first side, mounting means for mounting a plurality of conductor 
connector means in mounting positions in the shelf with access to the 
mounting positions at said first side, and a plurality of guide means each 
having first and second in-series guide parts and in each of which: the 
first guide part extends from the first side towards the second side of 
the shelf for guiding a flexible telecommunications cable transmission 
element positioned at the first side along a fixed path through the shelf 
towards the second side; and the second guide part is in-series with the 
first guide part to receive the transmission element from the first guide 
part, the second guide part being curved so as to guide the transmission 
element along a curved path and then through a corresponding mounting 
position towards the first side of the shelf. 
The termination shelf according to the invention thus operates to enable 
the telecommunications transmission element to be guided first in one 
direction through the shelf and then to be returned in the other 
direction. In a practical sense, where the first side of the termination 
shelf is positioned to be at a front of a distribution frame, then this 
enables a cable to be mounted upon the front side of the frame. The 
telecommunications cable transmission element, which may be the cable or a 
part of it, is then passed from the front towards the rear of the frame 
through the guide means of the shelf. The guide means operates to direct 
the transmission element around the second guide part so that it comes 
forwardly through the mounting position and is accessible to an operator 
from the front of the shelf or frame for connection into the connector 
means. As a result, there is no need for access to the rear of the shelf 
or frame by the installer and the shelf or frame may conveniently be 
mounted upon or against a wall thereby saving space. As a further result, 
the insertion of the transmission element into the shelf is simplified by 
the use of the guide means thereby avoiding the necessity of the installer 
to locate the transmission element along a tortuous path to reach the 
desired mounting position, particularly when mounted in a fiber 
termination frame. 
Alternatively, the shelf is mounted in a distribution frame to extend 
laterally of the frame so that the two sides of the shelf are spaced in a 
direction between the sides of the frame. 
The termination shelf according to the invention is particularly useful for 
connecting optical fibers of an incoming optical cable to the optical 
fibers of a customer's internal telecommunications network. However, it 
may also be used for frontal positioning and connecting of electrical 
telecommunications cable into the frame. 
The invention also includes a termination shelf for telecommunications 
cable and a plurality of conductor connector means, the shelf comprising a 
first side and a second side remote from the first side, and mounting 
means for mounting the plurality of conductor connector means in mounting 
positions in the shelf by sliding reception of the conductor connector 
means into the mounting positions through an access to each of the 
mounting positions at said first side, the shelf also comprising a 
plurality of guide means, one for each mounting position, each guide means 
having first and second in-series guide parts and in each of which: the 
first guide part extends from the first side towards the second side of 
the shelf for guiding a flexible telecommunications cable transmission 
element positioned at the first side and fed into the first guide part, 
along a fixed path through the shelf towards the second side; and the 
second guide part is in-series with the first guide part to receive the 
transmission element from the first guide part, the second guide part 
being curved so as to guide the transmission element along a curved path 
and through a corresponding mounting position towards the first side of 
the shelf.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
As shown in FIG. 1, an equipment frame 10 is provided for connecting 
optical fibers of optical cables 12 with the optical fibers forming the 
internal telecommunications network on a customer's premises. The 
equipment frame 10 comprises two fiber termination shelves 14 according to 
the embodiment, the shelves being vertically spaced apart. Each of the 
shelves 14 comprises horizontally in-series mounting positions 16 (see 
FIG. 4) for a plurality of conductor connecting means in the form of 
connection trays 18. Each shelf may be a detachable unit from frame 10 and 
may be mounted instead upon any suitable support or within a cabinet. 
Shelves 14 include trays 20 beneath stations 16 for holding optical patch 
cords 22 which comprise flexible protective tubes housing individual 
optical fibers. The patch cords 22 extend to terminals in equipment 
shelves 24 of the frame 10 for connection to individual optical fibers of 
the customer's network. The patch cords 22 may be changed in positions so 
as to alter the connections between the fibers of the incoming cables with 
the terminals in the equipment shelves 24. 
Alternatively, in a distribution frame 26 as shown in FIG. 2, the frame 
comprises a series of detachable shelves 14 similar to those shown in FIG. 
1 but without the addition of different types of shelves such as equipment 
shelves 24. In FIG. 2, the shelves 14 lie directly one above another. 
With the structures of FIGS. 1 and 2, optical fibers contained within 
flexible protective tubes of optical transmission elements 25 may be 
connected to connectors in the trays 18, as will be described, for 
connection to the customer's private internal network. The transmission 
elements collectively provide the cores of a plurality of cables 12, one 
for each shelf 14 which will be further discussed below. In FIG. 2, only 
two cables 12 are shown. 
Each of the trays 18 as shown in FIGS. 3 and 4 lies in a vertical plane and 
has a front end formed by end wall 27 and a rear end formed by end wall 
26. At the top and bottom of the tray in the position shown in FIG. 3, 
extend side walls 28 and 30 between the end walls 27 and 26. Spaced 
slightly behind the end wall 27 and parallel to it lies another wall 32 
which provides mounting positions for a plurality of optical connectors 34 
which extend through holes in the wall as shown. These optical connectors 
form parts of pigtail assemblies which also include bare optical fibers 36 
which are disposed within the tray as will be described. An additional 
wall 38 behind and parallel to the wall 34 is provided to align the fibers 
with the mounting positions for the connectors, and at this stage the 
fibers are enshrouded within short protective flexible polymeric tubes 40 
which extend from the connectors. 
Between the walls 38 and 26 extends a partition wall 42 which separates a 
housing region 44 for an incoming optical transmission element 25 from a 
storage compartment 46 for bared optical fibers. As can be seen from FIGS. 
3 and 4 the housing region 44 and the storage compartment 46 lie one on 
each side of the partition 42 between the walls 26, 28, 30 and 38. 
Within the housing region, the tray is provided with a minimum bend radius 
limiting means for the optical transmission element. This minimum bend 
radius limiting means comprises a short cylindrical member 48 projecting 
axially from the partition 42 into the housing region. The cylindrical 
surface 50 of the member 48 is spaced a substantial distance from the 
walls of the tray to enable the transmission element 25 to be passed 
around the surface 50 with freedom for substantial lateral movement. 
A retaining means is provided for holding the transmission element in the 
housing region, this retaining means comprising extensions 52 from the 
walls 26 and 38 and from the member 48, the extensions parallel to but 
spaced from the partition 42 and defining between them narrow gaps 54 for 
insertion of the transmission element. The housing region 42 is connected 
to the storage compartment 46 by an inclined slit 56 formed in the wall 
18. 
At the rear end of the storage compartment 46 is provided a curved guide 58 
for holding the transmission element 25 in curved orientation after it 
enters the storage compartment so as to direct optical fibers of the 
optical transmission element along a side of the storage compartment 
towards the wall 38. Within the storage compartment 46 is disposed a 
cylindrical member 60 of similar construction to the member 48 and around 
which bare fibers are to be organized. 
At one side of the storage compartment is provided a splice compartment 61 
which shares with the storage compartment the space bounded by walls 26, 
28, 30 and 38. The splice compartment is provided to house a plurality of 
splices 62 for optical fibers, the splices to be of conventional 
structure. An interconnecting space 64 and 66 is provided at each side of 
the splice compartment 61, these spaces interconnecting the storage 
compartment and the splice compartment. The storage and splice 
compartments are provided with a removable cover (not shown) for 
protecting bare fibers except when an installer or maintenance worker is 
operating within the compartments. 
The remainder of this description relates to the distribution frame 26. It 
should be understood, however, that the description also relates to the 
equipment frame 10. 
As can be seen particularly from FIGS. 1, 2 and 3, because of the design of 
each shelf 14, the distribution frame is designed for the frontal 
acceptance of the incoming optical cables 12 for connection to the 
connectors 34 of the various trays 18. The cables 12 are secured along a 
front of the distribution frame and, to enable the fibers of the cables to 
be passed into the trays 18 and connected with the connectors 34, it is 
necessary for the fibers to extend forwardly from the rear of the frame. 
This arrangement will also allow for the trays to be moved between a 
mounting station 16 and a non-operative position as will be described. As 
can be seen particularly from FIG. 4, the mounting positions 16 which lie 
side-by-side in each termination shelf 14, each comprise a means for 
slidably accepting an associated tray 18. This means comprises parallel 
horizontally and rearwardly extending upper and lower frame walls 68 and 
70 with the wall 30 of the tray slidably engaging the lower wall 70. The 
walls 68 and 70 define between them at the mounting position 16, a chamber 
sufficiently large to accept a tray comfortably, and dividing walls 72 are 
provided between adjacent mounting positions. 
Each of the cables 12 extends downwardly along the front of the frame. The 
sheath and jacket of each cable is removed at an appropriate position to 
expose the optical transmission elements 25 forming the core of the cable. 
Each termination shelf 14 includes a guide means for passage of the 
transmission elements, one for each mounting station 16, so as to guide 
the transmission elements rearwardly of the frame and then to enable the 
transmission elements to extend forwardly from a rear region of the frame 
and out through the front of the frame as required. In respect of each 
mounting station 16, the guide means comprises a first guide part which is 
defined by the wall 68 of the frame and a wall 78 slightly spaced above 
it, so as to define a passage 80 flanked by two side walls 72. An entrance 
to the passage 80 is provided by a circular hole 82 at the front of the 
distribution frame. Towards the rear of the distribution frame is provided 
a second guide part of the guide means. This second guide part comprises 
an end wall 84 having a forwardly facing semicircular guide surface 85 
which is an extension of the wall 78. The second guide part also includes 
a curved wall 87 forming an extension of the wall 68. The wall 87 is 
parallel to and spaced from the surface 85 to define a passage 89 
therebetween. The guide surface 85 and wall 87 extend downwardly as shown 
in FIG. 4. At its lower end, the guide surface 85 merges with the upper 
surface of the wall 70. At this point, wall 87 terminates to provide a 
forward facing exit 91 to passage 89. A supporting tray 86 is disposed 
horizontally beneath each of the holes 82 for supporting the optical 
transmission elements 25 as they extend from a respective cable 12 to each 
of the mounting stations 16. 
To connect optical fibers of a transmission element into its respective 
connector 34, the following procedure is followed. In respect of each of 
the mounting positions 16 and with the organizing tray 18 removed from the 
termination shelf 14, an appropriate optical transmission element or 
elements 25 is positioned along its respective tray 86 until it reaches 
the corresponding hole 82. The transmission element is then fed through 
the hole 82 by an operator standing at the front of the frame and the 
transmission element is guided along the passage 80 until it reaches the 
passage 89. The passage 89 then proceeds to guide the transmission element 
downwardly while forcing it along a curved path as the transmission 
element continues to be fed into the hole 82, until the leading end of the 
transmission element faces from the rear of the shelf 14 and of the frame 
in a forward direction and emerges from exit 91. Continued insertion of 
the transmission element results in the leading end of the transmission 
element moving out from the front of the shelf and of the distribution 
frame. When a sufficient length of the transmission element 25 has been 
fed from the front of the frame to be mounted into the respective tray, in 
a manner now to be described, the feeding of the transmission element 
through the guide means ceases. The relative positions of the parts at 
this stage are as shown in FIGS. 4 and 8. 
When the tray 18 is located outwardly from the shelf 14 and at the front of 
the frame 26, i.e. in a non-operative position, the transmission element 
25 is then passed through the gaps 54 in the retainer 52 and is wound 
around the cylindrical surface 50 of the member 48 in the storage 
compartment. At this stage, the coiled form of the transmission element is 
relatively small and lies closely against the cylindrical surface 50 of 
the member 48 (FIG. 9). The transmission element 25 is then fed through 
the slit 56 to bring it into the storage compartment 46. The slit is 
inclined along wall 28 so that the transmission element curves smoothly 
from the housing region 44 to the storage compartment while exceeding the 
minimum bend radius for the element. The transmission element then passes 
around the guide 58. In the region of the guide 58 and the slit 56 is 
provided a strain relief for the transmission element 25. This strain 
relief is provided by a slit 57 in alignment with slit 56 and into the 
edge of the partition 42. As shown by FIG. 5, the slit 57 is narrower than 
slit 56 so as to grip and deform slightly inwardly the flexible protective 
tube of transmission element 25. This is clear from FIG. 5 in which the 
transmission element is shown in chain-dotted outline being inserted into 
slit 57, and in full outline within the slit when the tube of the 
transmission element is inserted into and is gripped by the slit 57 this 
prevents lengthwise movement of the transmission element at this point. 
Upon the transmission element emerging from the other end of the guide 58, 
the tube of the transmission element is removed to expose the fibers 76. 
These fibers are then passed in coiled form around the member 60 in the 
storage compartment so as to store excess lengths of fiber for future use 
if required. The fibers 76 then pass through the gap 64 to the splicing 
region 61 at which they are individually spliced, by splices 62, to the 
pigtail fibers 36 of the pigtail assemblies. As shown in FIG. 3, the bare 
pigtail fibers then pass through the gap 66 and also progress in coiled 
form around the member 60 in the storage compartment before passing 
through the wall 38 to the connectors 34. While FIG. 4 shows the complete 
arrangement of fibers, for clarification purposes FIG. 6 shows the 
positions of the fibers 76 only and FIG. 7 shows the positions of the 
pigtail fibers 36 only. 
When a tray 18 is used in a termination shelf 14 mounted in the 
distribution frame 10 of FIG. 1, ends of the patch cords 22 are connected 
to the front ends of the connectors 34, by passing them upwardly through a 
gap 88 in wall 30 between the walls 27 and 32 (FIG. 3). Alternatively, 
when a tray 18 is used in a termination shelf mounted in the frame 26 of 
FIG. 2, optical fibers of the customer's own internal network and housed 
in flexible protective tubes 90 are connected to the connectors 34 in 
similar manner. 
With the tray 18 construction therefore, as can be seen from the above 
description, a compact arrangement is provided in which a single storage 
compartment houses both the incoming fibers 76 and the outgoing fibers 36 
side-by-side around the member 60. Because two compartments are not 
required for this operation, then the size of the tray 18 is minimized in 
this respect. Further to this, because the storage compartment and the 
housing region lie side-by-side and are separated by the partition wall 
42, then this further adds to the compactness of the design of the tray 18 
with the planes of the coils in the two compartments lying substantially 
parallel with the coils axially side-by-side. 
While the above description for insertion of the transmission elements 
relates to an optical fiber cable, nevertheless the insertion method for 
insertion of frontally mounted cable could be used for pairs of electrical 
conductors in an electrical transmission cable. Thus, the frontal access 
provided by the termination shelf and thus by the distribution frame is 
also applicable for use with electrical telecommunications cables. 
Upon the transmission element having been inserted into the tray 18 as 
described above, and with its fibers 76 interconnected with the pigtail 
fibers 36, it then becomes a relatively simple matter to insert the tray 
into its mounting position 16. As can be seen from a comparison of FIGS. 9 
and 12 of the application, as each tray 18 is moved into its mounting 
position, as shown in FIG. 12, the inward movement is accompanied by 
relative movement between the tray and the transmission element 25 
extending through the termination shelf 14. Thus, the transmission element 
moves progressively through an inlet 89 provided in the end wall 26 and 
into the housing region. Because the transmission element cannot move 
through the strain relief provided in the tray, then this extra length of 
transmission element within the storage region may only be accommodated by 
an increase in size of its coiled form around the member 48. Thus the 
coils expand radially within the housing region by movement away from the 
cylindrical surface 50. As can be seen from a comparison of FIGS. 9 and 
12, in FIG. 9 the coils lie substantially close to the surface 50 of 
member 48 and in FIG. 12 the coils have expanded outwards towards the 
surrounding walls 26, 28, 30 and 38. Should it be required to remove any 
particular tray from a termination shelf 14 in the distribution frame, 
then it is simply necessary to move the tray outwardly once more to the 
non-operative position shown in FIG. 9. During this movement, and as the 
transmission element is held in the guide within the termination shelf, 
then the transmission element is released through the inlet 89 so that the 
coils again reduce in size and move towards the cylindrical surface 50. 
Upon the tray being removed from the termination shelf, the housing region 
44 is accessible for maintenance purposes. The storage and splice 
compartments are also accessible. 
It will be appreciated therefore that with the above-described connection 
tray, an extremely compact design is formed. In addition, it is easily 
removed from within the termination shelf 14 for maintenance purposes 
while the shelf 14 itself is also designed to allow for ease of access 
from the front of the shelf whereby there is no need for the operator to 
be positioned at the rear of the shelf for assembling incoming cable. For 
this reason, the shelf may be mounted into a frame 10 or 26 which is 
attached directly upon a wall thereby saving space. Alternatively, the 
shelf may be mounted directly up against a wall. 
In another arrangement of equipment frame 100, shown in FIG. 13, 
termination shelves 102 of a second embodiment are stacked vertically in 
two spaced columns with the shelves in each column lying one above another 
so that each mounting position (not shown) lies in a horizontal instead of 
in a vertical plane as in previous figures. The termination shelves 102 
are basically of the same structure as the shelves 14 except that trays 20 
are not required because of the vertical configuration. 
In the arrangement of FIG. 13, connection trays 18 are fed laterally of the 
frame 100 into their mounting positions. With this configuration, incoming 
transmission elements are passed laterally of the frame through holes 82 
into the guide means of each shelf, the guide means extending laterally of 
the frame from one side of the shelf, i.e. at the openings to the mounting 
positions to the remote side of the shelf.