WO2015062645A1

WO2015062645A1 - Installation tool for an optical conductor storage unit and installation method

Info

Publication number: WO2015062645A1
Application number: PCT/EP2013/072677
Authority: WO
Inventors: Phil WEDGBROW; Guillaume VAUTRIN; Ian Dewi Lang
Original assignee: Prysmian S.P.A.
Priority date: 2013-10-30
Filing date: 2013-10-30
Publication date: 2015-05-07
Also published as: EP3063576A1

Abstract

It is disclosed an installation tool for an optical conductor storage unit comprising a storage area for storing at least one loop of said optical conductor, wherein said installation tool comprises a body with an axis and a winding surface for winding said optical conductor, wherein said body comprises a first end configured to be arranged close to said optical conductor storage unit and an opposite second end, and wherein a circumference of a section created by intersection of the winding surface and a plane perpendicular to the axis of the installation tool decreases substantially monotonically from said second end to said first end.

Description

INSTALLATION TOOL FOR AN OPTICAL CONDUCTOR STORAGE UNIT

AND INSTALLATION METHOD

BACKGROUND

The present invention relates to the field of optical networks. In particular, the present invention relates to an installation tool for improving installation of an optical fiber and/or an optical cable in a proper storage such as an optical termination box, an optical cable enclosure or the like. The present invention also relates to an assembly comprising a storage unit for an optical conductor and an installation tool. Furthermore, the present invention relates to a method of installing a length of an optical fiber and/or an optical cable in a proper storage such as an optical termination box, an optical cable enclosure or the like.

PRIOR ART

While the present invention is not limited to a particular storage for optical fibers, optical cables and/or optical components, the present description mainly concentrates on optical termination boxes for clarity reasons.

FTTH (Fiber To The Home) network is an optical access network providing a number of end users with communication services, e.g. with services requiring data transmission at a rate of some hundreds of Mbit/s or more.

Typically, FTTH network comprises a distribution cabinet located in the basement of the building where the end users reside and an optical cable (that is usually termed "in-line cable" or "riser cable") exiting the distribution cabinet. Typically, the in-line cable vertically runs through the building from the basement up to all the building floors.

At each floor of the building, one or more optical cables (usually termed "drop cables") may branch off from the in-line cable. The optical connection between the in-line cable and the one or more drop cables is typically made within a so-called optical transition box. Accordingly, each drop cable has an end optically connected to the in-line cable within the optical transition box. The opposite end of the drop cable is connectorized, i.e. at least one optical fiber of the drop cable is connected to a respective optical connector. The connectorized end of the drop cable is typically housed in an optical termination box located in the apartment of an end user. The optical termination box has openings allowing the end user to easily access the 5 optical connectors and connect to them one or more end user equipments (e.g. an Optical Network Termination like a set-top-box, etc.) for accessing the communication services provided by the FTTH network.

US 2009/0202213 A1 discloses a routing device for use in optical systems for routing and distributing optical fibres within optical networks, optical i o hardware, and optical joints thereof.

US 6,810,194 discloses an assembly for use in connecting optical fibers. The assembly includes a housing for optical fiber joints and a fiber routing device associated with the housing. The housing has a first inlet for receiving optical fibers from a primary side of an optical fiber network and a second

15 inlet for receiving optical fibers from a customer side of an optical fiber network. The fiber routing device has an outlet for feeding fibers from the customer side of the optical fiber network into the second inlet and two inlets for receiving the customer-side optical fibers for feeding to its outlet.

US 8,086,084 discloses a splice tray including a splice region and a fiber

20 management region to facilitate splicing together two or more fibers. A cover may be pivotally coupled to the splice tray. The splice tray may be pivotally coupled to a second splice trays by coupling the splice tray to the cover of the second splice tray using an attachment assembly to form a splice tray arrangement. An attachment assembly may include one or more protrusions

25 on the cover of the first splice tray that fit within openings and/or channels defined in the second splice tray or vice versa.

US 6,330,390 discloses a device for winding an optical fiber. The device includes a mandrel that is connected to a brace. In an operative mode, the brace engages a stabilizer and the stabilizer is fastened in a releasable

30 manner to an optical fiber storage assembly. The stabilizer can be fastened in a releasable manner to a spool, a hub, or a tray.

US 6,343,761 discloses a device for separating a first fiber portion from a second fiber portion of a fiber. The device includes a separator that can define at least one inner bearing surface adapted to restrain the first fiber portion from straightening when coiled within the separator.

SUMMARY OF THE INVENTION

An optical termination box may generally comprise a base, a cover and, optionally, a splice tray between the base and the cover. The splice tray may be hinged to the base and the cover may also be hinged to the base.

A length of spare optical conductor (typically, optical fiber) is properly arranged in a storage area on the splice tray. Such spare optical fiber can have a length in a range between 1 m to 4 m. Such arrangement generally comprises one or more loops of optical fibers loosely retained on the spice tray.

Retaining means, possibly in the form of securing tabs, are provided for avoiding that the loop(s) of optical fibers may leave the splice tray. In some known optical termination boxes, such securing tabs project substantially parallel to the floor of the splice tray. Therefore, a storage space is provided for the length of optical fiber. Such storage space is delimited in one direction by the floor of the splice tray and by the tabs and in the other direction by an outer surface of a central mandrel and by an inner lateral surface running around at least part of splice tray perimeter.

Gaps or slots are provided in the securing tabs for passing the optical fibers through the tabs so that the optical fibers remain, while loosely, retained on the splice tray in the storage space.

The Applicant has realized that introducing an optical conductor through the gaps or slots of the tabs requires dexterity of an assembly worker. The introduction is also time consuming and the risk is run of damaging the optical conductor if it is not properly managed.

In view of the above, the Applicant has tackled the problem of providing a tool for improving the step of installing optical conductors into storage units, e.g. improving the installation of an optical fiber into a splice tray or the installation of an optical cable into an optical cable enclosure. In particular, the Applicant has tackled the problem of providing a tool which is able to reduce the dexterity necessary for an assembly worker to install an optical conductor into a storage unit.

In addition, the Applicant has tackled the problem of providing a tool which is able to reduce the time for installing an optical conductor in a storage unit. Still in addition, the Applicant has tackled the problem of providing a tool which is able to reduce the risks of damages during installation of an optical conductor in a storage unit.

The Applicant has realized that wrapping an optical conductor around a cylindrical surface with sufficient tension to hold it to the surface and then attempting to move it axial ly along that surface can damage the optical conductor. Such wrapping of optical conductors would likewise require the cylindrical surface to have a radius generating some minimum bend radius at the optical conductor.

The Applicant has found that the above problems may be solved by providing an installation tool and installation method wherein an optical conductor is simultaneously delivered into a storage space of a storage unit as it is being wound around the winding surface(s) of the tool. The method may deliver the optical conductor directly to an inner hub or annular surface of the storage space of the storage unit, or deliver the optical conductor directly to an inner surface or surfaces in the storage space defined by portions of the tool itself. The tool comprises winding surface(s) which allow the optical conductor to be simultaneously and easily delivered into the storage space of the storage unit as it is being wound around the winding surface(s).

Preferably, at least a portion of the winding surface(s) of the tool may have a coefficient of static friction with the outermost layer of an optical fiber less than or equal to about 0.46, e.g. less than or equal to about 0.25 per the test data and makes an angle with the axis of the tool of ≥ about 7.5 degrees, e.g. ≥ about 1 2 degrees.

Preferably, at least a portion of the winding surface(s) of the tool has a surface roughness as measured by a Mitutoyo SJ400 Surface Roughness Tester, of < about 4.5 μιη, e.g. < about 0.8 μιη per the test data. More preferably, the whole winding surface(s) of the tool has a surface roughness as measured by a Mitutoyo SJ400 Surface Roughness Tester, of < about 4.5 μιη, e.g. < about 0.8 μιη per the test data.

Preferably, the axial height of the winding surface(s) of the tool may be≥ about 50% of the height of the tool.

Preferably at least a portion of the winding surface(s) of the tool may have a radius which is =<75% of the flexibility radius of the optical conductor. When the winding tension is released from the optical conductor, the conductor will thus have a tendency to release itself from those parts of the winding surface with a radius below 75% of the flexibility radius and the conductor will drop into the storage space.

Integral, permanently attached, or semi-permanently attached portions of the tool (i.e. portions which do not remain with the storage unit during storage of the optical conductor), may extend into the storage space of the storage unit, in addition to or instead of the winding surface(s). These portions may include, e.g. centering feet or locating lugs for positioning the tool onto the storage unit, which do not contact the bottom surface of the storage space, thus allowing delivery of the optical conductor directly to an inner hub or annular surface of the storage space of the storage unit. These portions may include, e.g. rounded locating lugs and/or e.g. annular radii for limiting the inward contraction of the conductor coil due to tension applied during winding, which do contact the bottom surface of the storage space, thus allowing delivery of the optical conductor directly to an inner surface or surfaces in the storage space defined by the tool itself, such as surface(s) closer to the exterior storage surfaces of the storage unit.

Optionally, the tool may releasable attach to the storage unit to avoid tipping, e.g. via an interference fit between features of the storage unit and features of the tool such as locating lugs.

According to a first aspect, the present invention provides an installation tool for an optical conductor storage unit comprising a storage area for storing at least one loop of said optical conductor, wherein said installation tool comprises a body with an axis and a winding surface for winding said optical conductor, wherein said body comprises a first end configured to be arranged close to said optical conductor storage unit and an opposite second end, and wherein a circumference of a section created by intersection of the winding surface and a plane perpendicular to the axis of the installation tool decreases substantially monotonically from said second end to said first end.

In examples of the present invention, at least a portion of the winding surface provides an angle with said axis of the installation tool equal to or higher than about 7.5 degrees.

In examples of the present invention, a cross section in said plane perpendicular to said axis comprises at least three edges or lobes projecting outwardly.

In examples of the present invention, said body is a frustum, such as a truncated pyramid or a truncated cone.

The winding surface may comprise a portion of an outer surface of said body. In alternative examples, the winding surface comprises a portion of an inner surface of said body.

In examples of the present invention, the body comprises means for properly positioning the tool onto said storage unit. Such means could comprise any of centering feet or locating lugs at the first end of said body.

According to a second aspect, the present invention provides an assembly comprising an installation tool as the above tool and an optical conductor storage unit wherein said optical conductor storage unit comprises a splice tray.

According to a third aspect, the present invention provides a method of installing an optical conductor in a storage area of an optical conductor storage unit, the method comprising: providing an installation tool as above, arranging said installation tool on a storage unit with the first end of the tool in proximity of said optical conductor storage unit, winding an optical conductor on the winding surface of said installation tool, wherein the winding surface is configured for forming loops of optical conductor and causing said loops of optical conductor to access the storage area of said optical conductor storage unit.

In examples of the present invention, arranging said installation tool on the storage unit comprises arranging said installation tool in a predetermined position.

In examples of the present invention, the step of removing the tool when a proper length of optical conductor has been moved from the winding surface of the tool to the storage area.

In examples of the present invention, when the winding tension is released from the optical conductor, the conductor will thus have a tendency to release itself from those parts of the winding surface with a radius below 75% of the flexibility radius so that the optical conductor will drop into the storage space.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become fully clear by reading the following detailed description, to be read by referring to the accompanying drawings, wherein:

- Figure 1 shows a tool according to one example of the invention arranged on a splice tray of an optical termination box;

- Figure 2 is a view of the optical termination box, without cover, of Figure 1 with optical fiber loops arranged loose in a storage space;

- Figures 3A and 3B are two different views of the tool according to one example of the invention;

- Figures 4A, 4B and 4C show respective sections of installation tool, corresponding winding surfaces and corresponding circumferences defined by the winding surfaces;

- Figure 5 shows a tool according to another example of the invention arranged on an optical cable enclosure while optical cable loops are formed;

- Figure 6 shows the tool of Figure 5 with optical cable loops formed around the tool ; and

- Figure 7 shows the cable enclosure with optical cable loops arranged loose in a storage space. DESCRIPTION OF EXAMPLES

For the purposes of the present description and claims, the term "winding surface" will indicate a surface of an installation tool. In particular, the winding surface comprises a contact surface between an optical conductor and an installation tool while the optical conductor is wound around an outer surface of the installation tool so as to form one or more loops. Such a winding surface is used during installation to guide an optical conductor downward toward a storage space of a storage unit. Such surface could be, for example, a portion of the (or the whole) surface of an inverted, truncated, right circular cone, the rounded corners and perhaps sides of an inverted, truncated, annular, trapezoidal pyramid, or the outer surfaces of multiple, outwardly angled, cylindrical rods attached at a base. The winding surface may actually be a covering, e.g. a tape.

For the purposes of the present description and claims, the term "winding surface" could indicate a continuous single surface. Alternatively, according to the present invention, the term "winding surface" could indicate plural discrete surfaces. Therefore, unless specifically indicated, the term "winding surface" will include both the singular (single continuous surface) and the plural (a plurality of discrete surfaces, even not connected one to the others). The term "winding surface" will also include, as it will become more clear from the following description, a surface made of two or more separate segments (or thin elongate surfaces), with each of said segments being a part of the outer surface of the installation tool. This is for instance the case when the outer surface of the installation tool comprises rather sharp corners or properly rounded corners. In that case, each of said segments comprises the points of the outermost ends of the corners. In fact, when an optical conductor is wound around the outer surface of an installation tool having outer surface corners (either rather sharp or rounded), the optical conductor will touch the outer surface of the tool at discrete points or along short lines. For each corner, the contact points will form a segment. In case the contact between the optical conductor and the tool outer surface results in a short line, for each corner the short lines will form a thin elongate surface.

For the purposes of the present description and claims, the circumference defined by the winding surface is the circumference of a section created by intersection of the winding surface and a plane perpendicular to the axis of the installation tool. This circumference typically decreases monotonically in the direction towards the storage unit when the tool is in use.

For the purposes of the present description and claims, an optical conductor will include any of an optical fiber and an optical cable.

For the purposes of the present description and claims, an optical fiber is a flexible optical transparent fiber through which light can be transmitted, comprising a core and a cladding made of glass, surrounded by one or more layers of protective coating preferably made of UV curable urethane acrylate.

For the purposes of the present description and claims, an optical cable is a structure comprising one or more optical fibers surrounded by a sheath of polymer material.

For the purposes of the present description and claims, the term "flexibility radius" is the minimum radius that 1 meter length of optical conductor is exhibiting under gravity force when clamped in one end in horizontal direction.

Figure 1 shows a tool 1 00 according to a first example of the invention arranged on a splice tray 202 of an optical termination box 200. Before describing the tool 100 and its operation, a brief description of an optical termination box 200 is given with reference mainly to Figure 2.

Indeed, Figure 2 shows an optical termination box 200 with some loops of an optical conductor 300, typically an optical fiber. The cover of the optical termination box, which is generally hinged to the base 201 , is not shown for not hiding the splice tray 202 and the optical fiber loops 300.

The base 201 comprises a bottom 201 a and four sidewalls 201 b to 201 e. The bottom 201 a is substantially preferably rectangular. The sidewalls are preferably substantially perpendicular to the bottom 201 a. The bottom has a first surface facing the cover (not shown) and the splice tray 202 and a second surface opposite to the first surface. The bottom 201 a is positioned so that its first surface forms an open compartment together with the four sidewalls 201 b to 201 e.

The base length may be about 1 10 mm, while the base width is about 90 mm and the base thickness is about 25 mm.

The base 201 is preferably made of a single piece of injection moulded thermoplastic material. More preferably, the base 201 is made from an ABS (Acrylonitrile Butadiene Styrene) polymer.

The splice tray 202 has preferably a substantially rectangular shape with rounded corners. Further, the splice tray 202 may comprise a floor and a fiber winding central element or mandrel 203. The mandrel 203 has a cylindrical body whose radius is preferably higher than the above mentioned predefined minimum bending radius. The mandrel 203 further comprises at least one fiber passageway 204 that obliquely cuts its cylindrical body.

The splice tray 202 may further comprise fiber guiding elements 205 and fiber guiding channels 206 that run close to the periphery of the splice tray 202. Both the fiber guiding elements and the fiber guiding channel may have straight portions and/or curved portions. The curved portions have the above mentioned predefined minimum bending radius.

The splice tray further comprises retaining tabs 21 0, 220 projecting substantially parallel to the splice tray floor. In the splice tray of Figure 2 there are provided four diagonal tabs 210 and two midline tabs 220.

Each of the diagonal tabs 210 comprises a central portion 21 1 connected to the periphery of the central mandrel 203 and a periphery portion 21 2 connected to the periphery wall of the splice tray 202. Both the tab central portion 21 1 and the tab periphery portion 21 2 are arranged cantilever and have a respective free end. Between the free ends of the tab central portion 21 1 and of the tab periphery portion 212 a gap 213 is provided. The gap 21 3 could be in the range of few millimeters, typically between 1 .5 mm and 5 mm, preferably about 2 mm. Preferably, the gap 213 of the diagonal tabs runs substantially parallel to the short side of the rectangular splice tray 201 . The purpose of the gap 21 3 will be better clarified below. As said above, there are provided two midline tabs 220 projecting from the peripheral wall of the splice tray 201 . A gap 223 is formed because the midline tabs 220 do not touch the central mandrel 203. The free end of the midline tabs 220 is preferably rounded.

Preferably, the splice tray 202 is made of a single piece of injection moulded thermoplastic material. More preferably, the splice tray is made from an ABS polymer.

The installation tool 1 00 according to a first example of the present invention is shown in Figure 1 in use. Figures 3A and 3B show such installation tool 100 not in use. The installation tool 1 00 and storage unit (optical termination box) 200 together, possibly with a length of optical conductor 300, form an assembly 400. Both the installation tool 100 alone and the assembly 400 are within the scope of protection of the present invention.

The installation tool 100 according to the first example comprises a pot- shaped body 1 01 . Preferably, the pot-shaped body 101 comprises a closed bottom 102 and lateral walls 1 03 projecting upwardly from the bottom 102. Preferably, the pot-shaped body 101 is hollow so that an empty space 1 05 is provided within the pot-shaped body 101 .

The bottom 1 02 of the pot-shaped body 101 has a shape and size compatible with the shape and size of the spice tray 202. More in particular, the shape and size of the pot-shape body 1 01 are such that when it is arranged on the splice tray 200, the gaps 21 3, 223 are not covered by the bottom 102. More preferably, the shape and size of the pot-shape body 101 are such that when it is arranged on the splice tray 202, the outer periphery of the bottom 102 substantially overlaps the central portion 21 1 of the diagonal tab 21 0 and aligns with its free end.

In one example, the bottom of the pot-shaped body 1 01 is about rectangular: the short side is from about 35 mm to about 45 mm, preferably about 41 mm; the long side is from about 55 to about 65 mm, preferably about 58 mm.

Preferably, centering members 1 05 are provided for properly and precisely arranging the pot-shaped body 101 with respect to the splice tray 202. In one example, shown in Figure 3B, the centering members are in the form of two facing feet 105. The feet can have isosceles trapezium shape with the short base made by a slightly curved line. The diameter of the slightly curved line could be about 40 mm. The centering feet could be about 4-5 mm high.

According to examples, the pot-shaped body 101 could be about 40 to 60 mm high, preferably about 50 mm.

Preferably, the size of the pot-shaped body 1 01 at the open top thereof is larger than the size of the bottom. The short size can be about 60 mm and the long side can be about 79 mm. Preferably, the shape of the pot-shaped body 1 01 is a truncated pyramid, having its greater base on the top and its smaller base close to the splice tray 202. Therefore, the pot-shaped body 1 01 tapers downwardly (it should be understood that the pot-shaped body is shown upside down in Figure 3B for showing the feet 105). The corners 103a between adjacent walls are rounded with a radius of some millimeters, for instance 5-6 mm. The base of the truncated pyramid could be a rectangle as in the attached drawings 1 -4, but it could also be a square, triangle, pentagram, hexagram, or octagon. Because the optical conductor only contacts the truncated pyramid on the rounded corners, there is less contact surface that facilitates the dropping of the conductor in the storage space.

In general terms, the body 1 01 has a frustum shape. For the purposes of the present application, a frustum is the portion of a solid (such as a cone or pyramid) that lies between two parallel planes cutting it. Preferably, it is a right frustum with axis X perpendicular to the basis.

In addition to the above examples, the tool could have a cross-section like a clover with three outwardly projecting petals, leafs, or lobes a cross-section like a four-leaf clover with three outwardly projecting petals, leafs or lobes or a cross-section with a higher number of outwardly projecting leafs. Preferably, the number of projecting lobes does not exceed 8.

The pot-shaped body 101 comprises a winding and guiding surface (also simply termed "winding surface" or "guiding surface"). In the example of Figures 1 and 3, the winding surface comprises at least a part of the outer wall surface of the truncated pyramid pot-shaped body. The winding surface of the first example is substantially made of the discrete rounded surfaces of the rounded corners 105a. It should be noticed that, in such example, the winding surface is substantially made of discrete surfaces which are connected through parts of the tool outer surface which are not in contact with the optical conductor when the optical conductor is wound around it.

As said above, in other examples, the body 101 can assume different shapes (for instance, cone truncated shape) but the winding surface may be still defined by the whole outer surface of the body or by a part thereof. In further examples, the winding surface may be the whole inner wall surface of the body or a part thereof. However, in case the winding surface is the inner wall surface, the bottom of the body should be open so that the optical conductor can drop down.

Preferably, the winding surface makes an angle with the axis of the tool of ≥ about 7.5 degrees, e.g.≥ about 12 degrees.

While the pot-shaped body 101 has been shown as a solid body, it can be provided also as a frame design. For instance, the winding surface could be provided by outer surfaces of multiple, outwardly angled, rods attached at a base. Profitably, the rods could have a cylindrical cross-section or an elliptical cross-section.

In further examples (not shown), the pot-shaped body 1 01 may comprise two mating semi-bodies.

The winding surface should be smooth. Preferably, at least a portion of the winding surface may have a coefficient of static friction with an outermost layer of an optical fiber of < about 0.46, e.g. < about 0.25. the static friction can measured by incline plane method which is disclosed by Wikipedia at www.en.wikipedia.org/wiki/inclined_plane#Analysis or at any corresponding page.

The tool 100 can be made of any metal or plastic material such as aluminum, steel, nylon, glass filled nylon or the like. In order to provide a smooth surface, the tool can be at least partially lined or covered with a low friction material, possibly in the form of a tape. Preferably at least a portion of the winding surface of the tool has a surface roughness, Ra, as measured by a Mitutoyo SJ400 Surface Roughness Tester, of < about 4.5 μιη, e.g. < about 0.8 μιη per the test data.

Figures 4A, 4B and 4C show respective perimeters of installation tool 100, 5 corresponding winding surfaces S and corresponding winding circumferences C defined by the winding surfaces. More in detail, each figure shows the perimeter of the pot-shaped body 101 of the first example. It may not correspond to a cross section.

According to the above definition, the winding surface S comprises at least i o a part of the surface of the rounded corners between adjacent faces. In principle, the winding surface could not be a continuous surface but it could be formed by four discrete segments, a segment for each of the rounded corners. Such segment is the line of contact points between an optical conductor wound around the pot-shaped body and the pot-shaped body 101 .

15 The contact between an optical conductor wound around the pot-shaped body and the pot-shaped body 1 01 could take place also along a thin elongate surface. Therefore, in such case, the winding surface is still not a continuous surface but it is formed by four discrete thin and elongate surfaces, an elongate surface for each of the rounded corners. In other

20 examples, the number of discrete thin and elongate surfaces could be 3, 5, 6, 7 or 8, depending on the shape of the pyramid base.

Figures 4A, 4B and 4C also show the winding circumference C, namely the circumference defined by the winding surface. Such a circumference is the circumference of a section created by intersection of the winding surface S

25 and a plane perpendicular to the axis of the assembly tool. This circumference typically decreases monotonically in the direction of contact between the tool and the storage unit. The various Figures 4 show the monotonic decrease of the outer section of the tool and the corresponding monotonic decrease of the winding circumference C.

30 The Applicant has realized that the invention provides the best performance when the installation tool is fixed to the optical storage unit. As said above, the fixing can be provided by an interference fit between the storage unit (possibly a splice tray) and the downwardly projecting feet of the winding tool. The splice tray flexibility ensures that the tool is gripped, therefore causing retention between the two parts.

Alternatively or in addition, splice trays could be designed with features that improve the above grip. Such features include one or more of barbs, limited interference molding pips, limited interference molding lines, a screwing arrangement between tab and tool, an aperture in the tool which houses, in an overlapping arrangement, a tab of the spice tray and a window which encapsulates a tab of the spice tray.

The method according to the present invention comprises arranging an installation tool 100 on a storage unit at a proper position and winding an optical conductor 300 on a winding surface S of said installation tool 100, wherein the winding surface S is configured for forming loops of optical conductor 300 and causing said loops of optical conductor to access a storage area of the storage unit 200. The storage unit 200 can be as the above described storage unit. Therefore, the optical conductor is caused to enter the storage area by passing through gaps 213, 223 of the tabs.

Thanks to the cone truncated (or the like) shape of the tool 100, the optical conductor 300 wound on the winding surface S of the tool 100 is caused to drop downwardly and to go through the proper gaps 21 3, 223.

Figure 5 shows a tool 1 00 according to another example of the invention arranged on a cable enclosure 200 while optical cable loops are formed. The tool 1 00 and the cable enclosure 300 together form an assembly 400. Figure 6 shows the tool 100 of Figure 5 with loops of optical cable 300 formed around the tool 100 and dropped downwardly due to conical shape of the tool 1 00. Figure 7 shows the cable enclosure 200 with optical cable loops arranged loose in the storage space 250 of the storage unit 200.

With reference to Figure 7, a description of the cable enclosure 200 will be given. The same reference numbers of the first example will be used as much as possible. The cable enclosure 200 comprises a planar base provided with channels 206 for optical cables 300. The cable enclosure 200 comprises a circular mandrel 203 and four L shaped arms 230. Each of the L shaped arms 230 is connected to the planar base 201 a, projects upwardly substantially vertically (231 ) and curves by about 90 degrees towards the central mandrel with a substantially horizontal tab 232. The free end of the tab 232 is preferably shaped in a way that follows the circumference of the mandrel 203 with an arc of circumference. Each tab 232 is separated from the mandrel 203 by a gap 233. The outer lateral surface of the central mandrel 203, the L shaped arms 230 and a portion of the planar base 201 a substantially define a storage area 250 for loops of optical cable 300.

The circular mandrel 203 has preferably a slightly conical shape, reducing its circumference from the planar base 201 a to the free end of the circular mandrel 203.

Similarly to the splice tray of the first example, there is the problem of improving the steps of assembly a length of optical conductor (in this example, an optical cable) 300 in the optical enclosure.

According to the present invention there is provided an installation tool 1 00, properly mating with a portion of the cable enclosure 200. Preferably, the installation tool 100 is designed for mating with the circular mandrel 203 which, as said above, has a conical shape. The installation tool 100 is fitted to the mandrel 203 and maintained in the precise position by interference or other appropriate means. Such appropriate means could include, for instance, a bayonet key fitting means or a twist fitting means which are known for a man skilled in the art.

The installation tool 100 comprises a tubular body 101 with an outer winding surface 103. Preferably, such tubular body 1 01 is hollow. Preferably, such tubular body 101 has a inner shape and size mating with the circular mandrel 203.

Preferably, the outer winding surface (which could be a discrete surface or a continuous one) is in the form of a cone truncated surface tapering downwardly. Preferably, the winding surface makes an angle with the axis of the tool of ≥ about 7.5 degrees, e.g.≥ about 12 degrees. The Applicant has performed some tests and has realized that when the angle is less than 7.5 degrees the optical conductor may not drop down into the storage space. On the other hand, when the angle is above 1 2 degrees the upper part of winding surface may be too large so that the conductor may not pass through the gaps 213.

While the tubular body has been shown as a hollow body, it can be a solid body or it can be provided also with a frame design.

In further examples (not shown), the tubular shaped body may comprise two mating semi-bodies.

The winding surface should be smooth. Preferably, at least a portion of the winding surface may have a coefficient of static friction with an outermost layer of an optical fiber of < about 0.46, e.g. < about 0.25. the static friction can be measured by incline plane method which is disclosed by Wikipedia at www.en.wikipedia.org/wiki/inclined_plane#Analysis or at any corresponding page.

The tool 100 can be made of any metal or plastic material such as aluminum, steel, nylon, glass filled nylon or the like. In order to provide a smooth surface, the tool can be at least partially lined or covered with a low friction material, possibly in the form of a tape.

Preferably, at least a portion of the winding surface of the tool has a surface roughness, Ra, as measured by a Mitutoyo SJ400 Surface Roughness Tester, of < about 4.5 μιη, e.g. < about 0.8 μιη per the test data.

The method according to the present invention comprises arranging an installation tool 100 on a storage unit 200 at a proper position and winding an optical conductor 300 on a winding surface of said installation tool 100, wherein the winding surface is configured for forming loops of optical conductor 300 and causing said loops of optical conductor to access a storage area of the storage unit. The storage unit can be the above described cable enclosure. Therefore, the optical conductor is caused to enter the storage area by passing through gaps of the tabs.

Thanks to the cone truncated (or the like) shape of the tool, the optical conductor wound on the winding surface of the tool is caused to drop downwardly and to go through the proper gaps.

Claims

An installation tool (1 00) for an optical conductor storage unit (200) comprising a storage area (202) for storing at least one loop of said optical conductor (300),

wherein said installation tool (100) comprises a body (101 ) with an axis (X) and a winding surface (103, 103a, S) for winding said optical conductor (300),

wherein said body (101 ) comprises a first end (102) configured to be arranged close to said optical conductor storage unit (200) and an opposite second end, and

wherein a circumference (C) of a section created by intersection of the winding surface (103, 103a, S) and a plane perpendicular to the axis (X) of the installation tool (1 00) decreases substantially monotonically from said second end to said first end (102).

The installation tool (100) of claim 1 , wherein at least a portion of the winding surface (103, 103a, S) provides an angle with said axis (X) of the installation tool (100) equal to or higher than about 7.5 degrees.

The installation tool (100) of claim 1 or 2, wherein a cross section in said plane perpendicular to said axis (X) comprises at least three edges or lobes projecting outwardly.

The installation tool (100) of any of claims 1 , 2 or 3, wherein said body (101 ) is a frustum.

The installation tool (1 00) of claim 4, wherein said body is a truncated pyramid.

The installation tool (100) of claim 4, wherein said body (1 01 ) is a truncated cone.

The installation tool (100) of any of claims 1 to 6, wherein said winding surface (103, 1 03a, S) comprises a portion of an outer surface of said body (1 01 ).

8. The installation tool (100) of any of claims 1 to 6, wherein said winding surface (103, 1 03a, S) comprises a portion of an inner surface of said body (1 01 ).

9. The installation tool (100) of any of claims 1 to 8, wherein said body (101 ) comprises means (105) for properly positioning the tool (100) onto said storage unit (200).

1 0. The installation tool (100) of claim 9, wherein said positioning means (105) comprises any of centering feet or locating lugs at the first end (102) of said body (101 ).

1 1 . An assembly (400) comprising an installation tool (100) according to any of claims 1 to 10 and an optical conductor storage unit (200) wherein said optical conductor storage unit comprises a splice tray.

1 2. A method for installing an optical conductor (300) in a storage area of an optical conductor storage unit (200), the method comprising:

providing an installation tool (1 00) according to any of claims 1 to 10, arranging said installation tool (1 00) on a storage unit with the first end (1 02) of the tool in proximity of said optical conductor storage unit (200),

winding an optical conductor (300) on the winding surface (1 03, 103a, S) of said installation tool (1 00),

wherein the winding surface (103, 103a, S) is configured for forming loops of optical conductor (300) and causing said loops of optical conductor to access the storage area (250) of said optical conductor storage unit (200).

1 3. The method according to claim 12, wherein arranging said installation tool (100) on the storage unit (200) comprises arranging said installation tool in a predetermined position.

14. The method according to any of claims 12 to 1 3, further comprising the step of removing the tool (1 00) when a proper length of optical conductor (300) has been moved from the winding surface (103, 103a, S) of the tool to the storage area (205).

1 5. The method according to any of claims 1 2 to 14, wherein when the winding tension is released from the optical conductor, the conductor will thus have a tendency to release itself from those parts of the winding surface with a radius below 75% of the flexibility radius so that the optical conductor will drop into the storage space.