Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
1997-04-29
2001-01-09
Ngo, Hung N. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C385S083000
Reexamination Certificate
active
06173098
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a production process for an opto-mechanical connector and to the connector itself.
STATE OF THE ART
In order to reduce the total cost for connecting optical fibers, multifibre connectors are used. The advantage of these is that the time-consuming and therewith costly mounting and supplementary work stages can be performed on several fibers at once.
One of the best known embodiments of multifibre connectors is the Japanese so-called MT-connector. This is based upon a precision part made of extruded thermosetting plastic in which the fibers are mounted (glued).
In another embodiment of multifibre connectors, an MT-compatible optical connector is extruded directly onto the fibers, see Swedish Patent Application No. 9301858-8. The fibers as well as guide pins are placed and fixed in V-shaped grooves in the cavity of the mould, after which the extrusion takes place. This method means that the gluing operation disappears, which rationalises the production and is expected to lower the cost for it.
In order to bring about the low damping which is aimed for, for example in a fiber connection, extremely dimension and fitting tight tolerances (better than 1 &mgr;m) are required. This is naturally associated with great difficulties and costs when using traditional machining methods such as milling and sparking in order to achieve the required precision in the mould. But even when this has been achieved there still remain problems. The fibers can be positioned incorrectly in the grooves if the grooves or the fibers are contaminated with e.g. left-overs from the casting. This can occur when the thermoplastic contains a large quantity of filler (approx. 70% by weight) consisting of quartz grains (with a diameter up to 50 &mgr;m), which can get into the V-grooves. Careful cleaning of the moulds and inspection after each extrusion cycle are therefore necessary, which leads to higher manufacturing costs.
A solution is to use small precision parts, so-called fixtures, as micro-mechanical supporting elements. The precision parts can be manufactured in e.g. silicon, whereby several of these can be obtained from a silicon disc, which can give a low manufacturing cost. The precision parts position fibers and guide pins in relation to each other and are moulded into the connector. This means that the precision requirement on the moulding cavity is reduced considerably.
European Patent Application No. 0 642 043 A1 shows an optical connector which comprises a precision part with a lid, which is moulded into the connector. The precision part has V-grooves for fibers and guide pins. The connector has an opening so that parts of the V-grooves for the fibers are exposed. The fibers can be watched through this opening when they are introduced into the connector and fixed when they are positioned in a predetermined place.
DISCLOSURE OF THE INVENTION
The object of the present invention is to obtain an optical connector, especially for fiber ribbons, which can be quickly and easily connected and which gives a very low damping. The connector shall have high mechanical precision and furthermore be simple and cheap to manufacture.
This is achieved by using a precision part as a micro-mechanical supporting element. The precision part is manufactured with grooves for fibers and guide pins. A lid is fastened on the precision part and the fibers and guide pins are positioned in the respective grooves, after which the encapsulating takes place.
The precision part or fixture is manufactured with straight and parallel grooves running on the upper side of the fixture from a first fixture side to a second fixture side, and which grooves are partially intended for optical fibers and partially for guide pins. A lid is fastened above the fixture, for example by anodic bonding. Fiber ends from, for example, a fiber ribbon cable are introduced into the grooves intended for the fibers from the first fixture side so that the fibre ends extend out through the second fixture side. Guide pins are introduced into the grooves intended for the guide pins. They can stick out through both the first and the second fixture side.
The structure obtained (fixture, lid, fibre ends and guide pins) is positioned in a mould cavity, whereafter the structure is completely or partially surrounded by a capsule, especially one made of plastic. The fibre ends can then be polished.
If the mould cavity is equipped with means so that the second side of the fixture is surrounded by plastic, any necessary polishing is made simpler because it is easier to polish a combination of fibers and plastic than fibers and fixture material. The means can also be so shaped (for example with bevellings) that the impressions from it form marks which make it possible during polishing to match the distance to the second side of the fixture.
An advantage of the present invention is that the precision requirements on the mould cavity are reduced considerably when micro-mechanical supporting elements are used.
Furthermore, the risk of contamination in the grooves is eliminated. This gives a more rational manufacturing.
Another advantage is that, if the connector is extruded or pressed directly onto the fibers and fixtures, the fibre does not need to be glued which simplifies and reduces the cost of the manufacturing.
Yet another advantage of the invention is that the moulded-in fixture functions as an anchor in the plastic and facilitates the fastening of the fibers.
Furthermore, any necessary polishing will be more simple if the second side of the fixture is surrounded by plastic, and consequently only a combination of fibers and plastic need to be polished. By using means which give an impression with markings, the distance to the second side of the fixture can be matched during polishing.
REFERENCES:
patent: 4950048 (1990-08-01), Kakii et al.
patent: 5351328 (1994-09-01), Kakii et al.
patent: 5441397 (1995-08-01), Eriksen et al.
patent: 5664039 (1997-09-01), Crinderslev et al.
patent: 5764833 (1998-06-01), Kakii et al.
patent: 0642043A1 (1995-03-01), None
patent: 2 256 286 (1992-12-01), None
patent: 62-276513 (1987-12-01), None
patent: WO96/13068 (1996-05-01), None
International-Type Search Report -National Application No. 9601703-3 Search Request No. SE 96/00513 -Mar. 5, 1997.
Patent Abstracts of Japan, vol. 12, No. 163, P-703, abstract of JP, A , 62-276513 (Sumitomo Electric Ind Ltd), Dec. 1, 1987.
Elderstig Håkan
Engstrand Jan-Åke
Eriksen Paul
Larsson Olle
Lindstrom Bengt
Burns Doane Swecker & Mathis L.L.P.
Ngo Hung N.
Telefonaktiebolaget LM Ericsson
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