Optical waveguides – Accessories – Splice box and surplus fiber storage/trays/organizers/ carriers
Reexamination Certificate
1998-09-17
2001-07-31
Font, Frank G. (Department: 2877)
Optical waveguides
Accessories
Splice box and surplus fiber storage/trays/organizers/ carriers
C385S136000, C385S137000
Reexamination Certificate
active
06269212
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the sector of packaging for optical devices and in particular relates to a method for performing fixing inside a container for optical connection components.
DESCRIPTION OF THE RELATED ART
For the purposes of the present patent application an optical connection component is understood as being a component suitable for connecting optical fibres together, for example: an optical coupler, an optical isolator, an optical divider or other passive optical devices. More generally, an optical connection component is defined as being any optical component in which there is at least one optical fibre carrying the optical signal in the component itself and at least one optical fibre emerging from it.
Passive optical networks, referred to as PONs, are networks which have arranged in them several units allowing the subdivision and distribution of a certain number of optical channels into a multiple thereof using a plurality of the said passive optical devices. The latter, inside the said units, are organized in turn inside boards, conventionally known as trays, which contain them and on which they are fixed.
The structure of the units which contain the trays or boards varies depending on the type of design, but fundamentally said units have a certain number of trays mounted on a single support.
The tray or board or container which houses the optical connection device is made, depending on the design, of plastic or metallic material and in general comprises a base, on which the said components are arranged, and a lid; the base and the lid are locked together by means of suitable closing means.
Moreover, this board may also have inside it a mechanism for wrapping or accommodating in a suitable manner the sections of excess fibre which are connected to the component inside it; in fact, the optical components may be curved only up to a certain minimum radius of curvature, otherwise signal attenuation or even damage to the fibre structure occur. Therefore, in some cases it is advisable to keep inside the said trays some sections of excess fibre which are arranged so that the signal inside the fibre is not subject to excessive attenuation or the structure of the fibre itself is not damaged, in addition to allowing the operations involving welding of the fibres themselves to be easily performed.
Among the given optical connection components, the junctions between sections of optical fibres are performed commonly using special apparatus which performs intimate bonding of the ends of the two fibres by means of butt welding, so as to minimize the signal attenuations due to the connections themselves; each welding point thus provided is encapsulated in a protective packaging. Said welding points in this way are protected and forming a type of optical connection component provided with a protective packaging. Then, said junctions are inserted into the various trays in accordance with a suitable logic for optimization of the spaces inside them.
As regards planar waveguide optical components, these are usually encapsulated in silicone rubber or in an equivalent elastomeric material so as to ensure adequate protection against both mechanical and environmental stresses. The component with the silicone packaging is then inserted into the actual package which has the function of rigidly supporting the component itself.
In both cases described above, the components inside their packages are inserted inside the trays by means of silicone bonding agents or adhesives. Then the trays are closed and fixed onto the appropriate supports of the various units inside the passive optical networks (PONs).
The Applicant has ascertained that the assembly operation for the components inside the trays is sometimes difficult, since the latter do not have large spaces inside them for insertion of these packages, the volume of which is often considerable. Moreover, in view of their rigidity, handling them is nevertheless complex during insertion. Finally, fixing them inside the tray, by means of said silicone bonding agents or adhesives, may not satisfy the requirements of reliability over time as a result of the action of external agents which could modify the characteristics thereof.
U.S. Pat. No. 4,373,776 describes a protection unit for optical components such as junctions between optical fibres and optical attenuators inside which a plurality of trays is fixed, by means of hinges, to the centre of the base of the unit itself. These trays are in the form of thin boxes and are arranged, parallel to one another, transversely on the base of the unit and have inside them the said junctions between optical fibres and optical attenuators. The sections of fibres emerging from each tray are channelled into two guides arranged longitudinally on both sides of the base of the unit.
Each tray has inside it a fastening support for the said components comprising a strip of elastomeric material which has a plurality of transverse recesses formed on its surface inside which the components themselves are inserted by means of pressure. Following insertion of the components, a closing element covers the trays in the zone occupied by the strip of material which retains the components themselves, helping further to fix them in the tray.
This strip of elastomeric material may be made by means of extrusion or by means of fusion and preferably is composed of expanded rubber.
U.S. Pat. No. 5,519,804 describes a tray inside which a device for retaining optical connection components, in particular for junctions between optical fibres, is removably inserted. This device comprises a layer of elastomeric material in which U-shaped recesses containing the said junctions are formed. The tray also has inside it a device for wrapping the sections of excess fibre emerging from the various connectors arranged in the tray.
BRIEF SUMMARY OF THE INVENTION
According to the present invention it has been found that, by manufacturing a packaging for covering an optical connection component from an elastomeric material, such as silicone rubber for example and in a shape geometrically suitable for inserting it and binding it by means of interlocking engagement into a container, it is possible to avoid using an actual rigid package for the component itself. In fact, the latter is inserted with its rubber covering inside the trays and suitably fixed inside. Assembly of the tray and the components inside it is facilitated and the packaging of elastomeric material provides the components inside it with the necessary protection from mechanical and environmental stresses.
According to a first aspect thereof, the present invention relates to a method for performing fixing inside a container for optical connection components, characterized in that it comprises the following steps:
providing a protective packaging made of elastomeric material encapsulating at least one optical connection component;
inserting said packaging containing said at least one component inside said container;
closing the container.
In particular, this step of providing a protective packaging made of elastomeric material encapsulating at least one optical connection component comprises:
inserting an optical connection component into a mould of suitable shape for subsequent positioning of said packaging in the container;
filling the mould with the material forming is the packaging in the fluid state;
cross-linking the material forming the packaging with the component inside;
extracting the packaging itself from the mould.
In particular, said step of inserting said packaging containing said at least one component inside said container comprises:
binding by means of interlocking engagement the packaging containing the component into the container;
Preferably the operation of filling the mould is performed by means of injection moulding.
In particular, said elastomeric material forming the packaging is a resin with a cross-linking temperature lower than 80° C., an operating temperature range of between −40° C. and +85° C. and a Shore hardn
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Font Frank G.
Nguyen Sang H.
Pirelli Cavi E Sistemi S.p.A.
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