Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
2000-04-07
2002-05-28
Sircus, Brian (Department: 2839)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C385S070000, C439S271000
Reexamination Certificate
active
06394662
ABSTRACT:
This invention relates to an optical fibre connector arrangement.
A known connector element receives at one end a sheathed optical fibre cable, and the individual optical fibres are separated out within the connector element. Each of the individual optical fibres is terminated with a ferrule at the cut end. The ferrules butt against an expanded beam lens arrangement which enables the optical signals to bridge the gap between coupled connector elements.
It is known to provide an end face of the connector with a transparent window, and ferrules at the end of the individual fibres are positioned internally adjacent the window.
This window provides protection for the lens assemblies associated with the ferrules, and provides an easily cleanable surface. Conventionally, the window is arranged as an insert which is provided in a bezel component. A seal is first located in a recess of the bezel, and the window insert is then inserted over the seal. The bezel assembly is then screwed into a recess in the end face of the connector element with the window insert clamped against the end face of the connector element. This assembly operation is delicate and may be particularly difficult in a remote site and in adverse conditions. Thus, maintenance may be difficult.
The ferrules are typically carried by a ferrule carrier which retains the sheathed fibre cable at one end and an individual ferrule or ferrules at the other end. A problem with existing ferrule carriers for connector elements is that the during assembly of the connector element, the individual fibre or fibres are fed into the opening for the sheathed fibre cable, and then pushed along the ferrule carrier. If the ferrules at the end of the fibres catch any obstruction or else miss ferrule openings provided for them, the fibres may be caused to buckle, are difficult to extract and may become damaged. The assembly of the connector element therefore may result in damage of the fibres, which may or worse may not be detected.
It is also known to use hermaphroditic couplings, so that identical connector elements may be coupled together. It is known for such connector elements to be provided with O-ring seals at their end faces. When two identical connector elements are mated together, the seals are pressed against each other to provide a protected space which prevents dirt or moisture interfering with the optical path between the connector elements. Conventionally, the O-ring seals are glued into a recess in the end face of the connector element. However, it has been found that the rubber-to-rubber contact between the seals can result in the seals becoming detached more readily than experienced in a rubber-to-metal seal environment. To replace the seals is then difficult, because adhesive is required. The connector elements may be situated in remote locations, so it is desirable for maintenance to be as easy as possible.
According to a first aspect of the invention, there is provided an optical fibre connector element comprising a connector body which receives an optical fibre, the optical fibre terminating with a ferrule, the connector body having an end face which is provided with a transparent window, the ferrule being positioned internally adjacent the window, in which when two identical such connector elements are mated to connect optically the optical fibres the ferrules behind the windows are aligned, wherein the window is provided by an insert which is inserted into a recess in the end face, the insert comprising:
a moulded plastics carrier having an opening for the window and a set of openings for fixing screws;
a seal component which is overmoulded over the carrier and which lines the opening for the window and extends over the fixing screw openings;
a window component which is located in the window opening; and
a set of fixing screws, wherein the seal component is for retaining the window component and the fixing screws in place to define a pre-assembled insert.
The invention in this first aspect provides a single carrier component which includes an integral seal component for the window. This seal enables the window and the screws to be held in place. Therefore, the insert may be assembled as a single component, so that all that is required on site to replace a damaged window is to undo the screws of the damaged insert, and do up the screws of the new pre-assembled window insert.
Preferably, the base is lined with the seal component such that when the window is initially placed in the opening it stands proud of the surface of the carrier. This enables the final position of the window to be determined by the components of the connector element, so that the window can be guaranteed to be perpendicular to the direction of propagation of the optical signals, which is desired for the window to have minimum effect on the signals.
The end face preferably further comprises a seal surrounding the insert, the seals of each connector butting against each other to provide a seal when two identical such connector elements are mated to connect optically the optical fibres. The windows are thus protected from damage and interference by moisture and particles.
According to a second aspect of the present invention, there is provided an optical fibre connector element comprising a connector body which receives an optical fibre, the body having an end face which is provided with an O-ring seal, in which when two identical such connector elements are mated to connect optically the optical fibres, the O-ring seals of each connector butt against each other to provide a seal, and wherein the O-ring seal is provided in a channel in the end face of body, the channel having opposed side walls with at least a portion of at least one of the side walls being tapered thereby enabling the O-ring seal to be retained frictionally in the channel.
The frictional engagement may be arranged to retain the seal more securely than the glued arrangement of the prior art. Furthermore, the replacement of the seal is facilitated.
Preferably, the optical fibre terminates with a ferrule, and the end face of the body is provided with a transparent window, the O-ring seal being disposed around the window and the ferrule being positioned internally adjacent the window. The seals thus provide protection for the windows, through which the optical signals pass.
According to a third aspect of the invention, there is provided an optical fibre connector element comprising:
a connector body which receives a sheathed optical fibre, the optical fibre terminating with a ferrule having a width greater than the width of the optical fibre;
a ferrule carrier provided within the body, the sheathed optical fibre being retained in a sheath opening at one end of the ferrule carrier and the optical fibre ferrule being located in a ferrule opening at the opposite end of the ferrule carrier,
wherein a channel is provided between the sheath opening and the ferrule opening which acts as a guide passage for the optical fibre, and wherein the channel is provided with a guide ramp for directing the optical fibre radially out of the ferrule carrier, the guide ramp being provided with a slot having a width less that the width of the ferrule and greater than the width of the optical fibre.
The guide ramp ensures that the individual fibre or fibres are directed out of the ferrule carrier by guiding the ferrule at the end of the fibre, so that they are safe from damage. The slot enables the fibre then to be slid into place with the fibre located in the slot. This operation does not require significant bending of the fibre or fibres.
The ferrule openings are preferably provided at the end of a radial passage in an end face of the carrier, so that the ferrules may also be slid sideways into the ferrule openings.
In all aspects, the connector body may be provided with coupling means to enable two identical such connector elements to be mated to connect optically the optical fibres, for example a hermaphroditic bayonet fitting.
REFERENCES:
patent: 3990779 (1976-11-01), McCartney
patent: 4213464 (1980-0
ITT Manufacturing Enterprises Inc.
Prasad Chandrika
Sircus Brian
Turner Roger C.
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