Note: Descriptions are shown in the official language in which they were submitted.
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OoticaI Fibre Distribution Svstem
The present invention relates to an optical fibre distribution system, to a
kit of
parts for forming such a system, to an optical fibre storage region module for
an
optical fibre distribution system, and to a method of connecting an optical
fibre and
storing a spare length thereof in an optical fibre distribution system.
Several types of optical fibre distribution systems, which are commonly known
as frames or racks, are used today. For example, one type of system is
disclosed in
United States Patent No. 5402515 (3M). This patent discloses a system which
comprises a frame having several bays for receiving connector modules,
associated
jumper organizers for storing spare lengths of jumpers (which may also be
called
pigtails or patch cords and comprise ruggedized optical fibres which are
connected to
the connector modules), and upper and Lower troughs for conveying jumper
fibres
between adjacent bays. Spare lengths of jumpers are stored in vertical
raceways
between the bays of connector modules, with each vertical raceway containing
several
spools which support the jumpers in such a manner that there are never more
than two
continuous bends of more than 90°.
A different system of storing spare lengths (sometimes referred to a$ slack or
excess) of optical fibres in a distribution system is disclosed in United
States Patent
No. 50I312I. In this system, the spare optical fibre lengths are stored in a
cabinet or
module which may form part of a stack of connector cabinets or modules in a
distribution frame. The cabinet which stores the spare fibre contains a
plurality of
trays which are slidably received within the cabinet. A take up spool is
provided on
each tray, and the slack of a patch cord fibre is stored on each tray by
winding the take
up spool on that tray.
There are disadvantages with each of these systems. While the spare jumper
length storage system disclosed in US 5402515 has the advantage of simplicity,
it has
the disadvantage of providing only poor organization of the spare jumper
lengths, and
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tangling of jumpers is therefore possible, and even likely.
This tangling leads to the disturbance of other jumpers when
attempting to access one particular jumper, which can cause
losses in optical signal transmission. Furthermore, the
tangling of jumpers is exacerbated by the fact that the
vertical raceways (where the spare jumper lengths are
stored) are also used to route jumpers between the bays of
the distribution system, and so these raceways are normally
very crowded with jumpers. This also makes the provision of
wide vertical raceways between the bays a necessity, which
is disadvantageous in situations where there is insufficient
space available for such wide vertical raceways.
The system disclosed in US 5013121 provides a much
greater degree of organization of spare optical fibre
lengths (e. g. spare jumper or patch cord lengths), but this
improved organization is achieved at the cost of greatly
increased installation complexity (and consequently
installation time). Spare lengths of fibre must be stored
individually on the trays in the cabinet in a time-consuming
2D and laborious installation procedure, and a correspondingly
time-consuming and laborious procedure is also required in
order to gain access to the fibre once stored. Furthermore,
the cabinet is a complex and intricate construction which
can store a maximum of only 48 patch cords or jumpers, and
it is thus a costly and space-consuming design despite its
superficially compact appearance.
There is thus a need for an optical fibre
distribution system in which spare lengths of fibre are
. stored in an organized yet compact manner, and which
provides quick and easy installation and access of such
stored fibre in a manner which reduces the risk of
disturbance of other stored fibres. The purpose of the
present invention is to provide such a system.
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Accordingly, a first aspect of the present
invention provides an optical fibre distribution system,
comprising: (a) at least one stack of optical fibre
interconnection modules, having a front and a back each
transverse to its width; and (b) at least one optical fibre
storage region located in at least one said stack of
interconnection modules, which storage region, in use,
stores spare lengths of one or more optical fibres which
extend between respective interconnection modules, wherein
in the assembled condition the or each storage region is
located non-movably in the stack of interconnection modules,
and wherein the or each storage region comprises a plurality
of elongated supports in at least one series which are
mutually spaced-apart across at least part of the width of
the stack of interconnection modules, the supports forming
part of or being mounted to a fixed structural member of the
storage region of the distribution system so as to extend at
least part way across the storage region, such that, in use,
each spare length of optical fibre may be routed into the
storage region and routed around at least one of the
supports which may be selected to provide at least
approximately a correct storage length required for that
spare length of optical fibre, wherein each of the plurality
of elongated supports is longer than an adjacent one of the
plurality of elongated supports from one side to an opposite
side of the stack of interconnection modules.
A second aspect of the invention provides a kit of
parts for forming an optical fibre distribution system,
comprising: (a) a plurality of optical fibre interconection
modules having a front and a back each transverse to its
width, which, in use, are arranged in a stack; and (b) at
least one optical fibre storage region module which, in use,
is located in at least one said stack of interconnection
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modules, which storage region, in use, stores spare lengths
of one or more optical fibres which extend between
respective interconnection modules, wherein the or each
storage region, in use, is located non-movably in the stack
of interconnection modules, and wherein the or each storage
region comprises a plurality of elongated supports in at
least one series which are mutually spaced-apart across at
least part of the width of the stack of interconnection
modules, the supports forming part of or being mounted to a
fixed structural member of the storage region of the
distribution system so as to extend at least part way across
the storage region, such that, in use, each spare length of
optical fibre may be routed into the storage region and
routed around at least one of the elongated supports which
may be selected to provide at least approximately a correct
storage length required for that spare length of optical
fibre, wherein each of the plurality of elongated supports
is longer than an adjacent one of the plurality of elongated
supports from one side to an opposite side of the stack of
interconnection modules.
A third aspect of the invention provides an
optical fibre storage region module for an optical fibre
distribution system, which module, in use, is located non-
movably in the distribution system and stores spare lengths
of one or more optical fibres which are connected in the
distribution system, the module having a front and a back
each transverse to its width comprising a plurality of
elongated supports in at least one series which are mutually
spaced-apart across at least part of the width thereof, the
supports forming part of or being mounted to a fixed
structural member of the module so as to extend at least way
across the module such that, in use, each spare length of
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optical fibre may be routed into the module and routed
around at least one of the elongated supports which may be
selected to provide at least approximately a correct storage
length required for that spare length of optical fibre,
wherein each of the plurality of elongated supports is
longer than an adjacent one of the plurality of elongated
supports from one side to an opposite side of the module.
A fourth aspect of the invention provides a method
of connecting an optical fibre and storing a spare length
thereof in an optical fibre distribution system according to
the first aspect of the invention, comprising:
(a) connecting opposite ends of the optical fibre
in respective interconnection modules;
(b) routing a said spare length of said connected
optical fibre into the storage region;
(c) selecting at least one of the supports to
provide at least approximately the correct storage length
required for that spare length of optical fibre; and
(d) routing the spare length of optical fibre
around the selected support(s).
Preferably, the step of routing the spare length
of optical fibre around the selected supports) comprises
hooking a bend in that optical fibre around the selected
support(s), e.g. by passing the bend around an end (e.g. a
front end) of the support or through a gap in the support.
The invention has the advantage that it provides a
simple, organized and compact system of storing spare
lengths of optical fibre (which will normally be ruggedized
fibre, e.g. pigtails, patch cords or jumpers) because the
storage region comprises a plurality of supports which are
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mutually spaced-apart across at least part of the width of
the stack of modules such that each spare length of optical
fibre may be routed into the storage region and routed
around at least one of the supports which may be selected to
provide at least approximately the correct storage length
for that spare length of optical fibre.
This manner of spare fibre length storage is
compact because it does not require the use of trays for
storing individual (ruggedized) fibres; also, because the
storage is carried out within the stack of modules, it does
not require wide vertical
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raceways between such stacks or bays. It furthermore provides good
organization
since the spare fibre Iengths-are organized according to their length by
virtue of the
fact that the support or supports around which they are routed is/are selected
according
to the length of spare fibre which needs to be accommodated. This means that
the
spare lengths of fibre routed into the storage region are each organized into
one of a
plurality of different possible routes, thus aiding subsequent accessibility.
Ordinarily,
of course, there will be more than one (ruggedized) fibre following each
route. It has
been found that this system of spare f bre length storage can provide
adequately
organized storage of up to 300 or more ruggedized fibres in the same volume
and
shape as the module disclosed in US 5013121 (which typically has dimensions
of:
height 8" (20.3cm); depth 12" (30.Scm); width 21" (53.3cm)).
The optical fibre storage region preferably comprises a module which may be
included in a stack of interconnection modules (or the like) as and where
required.
Advantageously, the or each storage region module may have substantially the
same
size and shape as the, or at least one of the, interconnection modules.
Alternatively,
however, at least in some embodiments, the storage region may be a part of, or
attachable to, a frame (or the like) of the distribution system, other than as
a module.
For example, the supports may be part of, or attachable directly to, such a
frame.
The interconnection modules preferably includes means for connecting the
optical fibres (spare lengths of which are stored in the storage region(s)) to
other
optical fibres and/or devices (e.g. optical devices). They may, for example,
include
optical connectors, splices, splatters or the like. They most preferably
include a patch
panel or other patching means.
The plurality of supports in the optical fibre storage region preferably
comprise
at least one series of supports (e.g. threee or four or mare) which are
mutually spaced-
apart across at least part of the region, i.e. across at least part of the
module or stack of
interconnection modules. Advantageously, each support may comprise at least
one
elongate member which extends in a direction which is transverse, and
preferably
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substantially perpendicular, to the width of the stack of interconnection
modules.
Each support is preferably shaped so that the radius of curvature of an
optical fibre
routed around it in use cannot be less than the normal operational minimum
bend
radius of the fibre (in order to avoid damage of the fibre and/or optical
transmission
losses).
Preferably, spare lengths of optical fibre are routed into the optical fibre
storage region through at least one side thereof {i.e. through at least one
extreme end
of its width). The fibres may, for example, be routed into the storage region
from one
side only, e.g. to avoid tangling of the stored lengths. Ordinarily, when the
fibres
enter the storage region from only one side, they may subsequently be removed
without the need to remove any of the other stored fibres. Alternatively,
optical fibres
may be routed through the storage region from one side to the other across its
width.
In some preferred embodiments of the invention, the or each optical fibre
storage region has at least one support located at the point of entry/exit of
an optical
fibre into the storage region, the support being azranged so that an optical
fibre
entering/exiting the storage region may be routed around it.
In certain preferred embodiments, the supports (e.g. elongate support
members) increase in length from one side to the other side of the stack of
interconnection modules. This has the advantage that it may improve the ease
of
installation and/or removat of stored optical fibre lengths into or out of the
storage
region_ The supports preferably decrease in length away from a side of the
region
from which the fibres enter the region (see, for example, Figure 2 of the
drawings).
The or each stack of interconnection modules preferably has a front and a back
which are each transverse to its width (the stack is preferably substantially
rectangular
or square in plan view), for example with the front arranged to be readily
accessible,
and the back arranged to be less readily accessible, in use. The supports of
the or each
storage region are preferably mounted on a structural member of the
distribution
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system located at or near the back of the stack of interconnection modules. In
embodiments in which the or each storage region comprises) a module, the
structural
member preferably comprises part of the module, e.g. a back plate or frame of
the
G
module. Otherwise, the structural. member may, for example, comprise a frame
or the
like) of the distribution system, e.g. upon which the interconnection modules
are
mounted. In preferred embodiments, the support members (e.g. elongate members)
extend closer to the front of the stack of interconnection modules as their
length
increases from one side to the other side of the stack.
The invention will now be described, by way of example, with reference to the
accompanying drawings, of which:
Figure 1 illustrates, schematically, an optical fibre distribution system
according to the invention;
Figure 2 illustrates, schematically, an optical fibre storage region
according to the invention; and
Figure 3 illustrates, schematically, how a spare length of optical fibre is
stored in a storage region of a distribution system according to
the invention; and
Figure 4 illustrates, schematically, an alternative way of storing a length
of optical fibre in another storage region of a distribution
system according to the invention.
Figure 1 illustrates, schematically, an optical fibre distribution system 1
according to the invention. The system comprises two stacks (other numbers of
stacks
are, of course, possible) of optical fibre interconnection modules 3, and
ducting 5
around the stacks through which cables and/or fibres may be routed. In each
stack is
an optical fibre storage region 7. Illustrated schematically in each storage
region 7 are
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a plurality of supports 9 which are mutually spaced-apart
across the width of their respective stack. The storage
region 7 illustrated in the left-hand stack (as drawn) has a
single series of supports, whereas the storage region 7
illustrated in the right-hand stack has two series of
supports. Ruggedized optical fibres 11 (e. g. pigtails)
which extend between respective interconnection modules 3
are routed through the side ducts and into their respective
storage region 7 through the closest side thereof. The
optical fibres 3 are hooked around the appropriate
supports) 9 so that the spare or slack fibre is taken up.
Figure 2 illustrates, schematically, an optical
fibre storage region 7. The storage region 7 includes a
series of elongate support members 9 extending from the back
of the region in a direction substantially perpendicular to
the width of the stack. The support members 9 are mutually
spaced-apart across the width of the storage region, and
each one is curved in cross-section so that an optical fibre
9 hooked around it is not bent at a radius below its normal
operation minimum bend radius. The elongate support members
decrease in length from the side of the storage region
through which the fibres enter. This facilitates
installation and removal of the fibres, particularly those
fibres for which the greatest spare length is stored in the
storage region.
Figure 3 illustrates three steps in the connection
of an optical fibre and the storage of a spare length
thereof, in an optical fibre distribution system according
to the invention. In step 1, opposite ends of an optical
fibre 11 (e.g. a ruggedized optical fibre) are connected in
two different interconnection modules (although they could
be connected in the same interconnection module). This
leaves a spare (slack) length 13 of the optical fibre which
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needs to be stored. In step 2 the spare length 13 is routed
into an optical fibre storage region 7 which is situated in
a stack of interconnection modules 3. More specifically
this is achieved by bending a middle portion of the optical
fibre and inserting this bend 15 into the optical fibre
storage region 7. In step 3 the spare length of optical
fibre is routed around an appropriate support 9 which is
selected from the series of available supports to provide
the correct storage length required to take up that spare
(slack) length of optical fibre, more specifically this is
achieved by hooking the bend 15 over the front end of the
appropriate support 9.
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Figure 4 illustrates, schematically, another storage region 7 of a
distribution
system according to the invention. In this storage region, there are supports
9 located
in (some or all of) its corners. These corner supports may guide optical
fibres 11
where they extend into the storage region. As shown in a dashed line, optical
fibres
may extend through the storage region from one side to the other, i.e. across
the entire
width of the storage region.
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