Optical waveguides – Accessories
Reexamination Certificate
2002-12-20
2004-09-07
Patel, Tulsidas C. (Department: 2839)
Optical waveguides
Accessories
Reexamination Certificate
active
06788868
ABSTRACT:
FIELD OF THE INVENTION
This invention relates, generally, to communication networks and, more particularly, to providing maintenance access to modules at network nodes.
BACKGROUND
As broadband networks continue to move from the experimental realm to the order of the day for network and service providers, the competition-driven need for providers to reduce costs of implementation increases proportionally. Community Antenna Television (“CATV”) has traditionally relied on metallic coaxial (“coax”) cabling to deliver video signals. Increasingly, optical fiber networks are used to transport analog and digital information signals from a provider to subscribers. Connection is typically made to the network with a drop cable between the subscriber's premise equipment and a node mounted near the subscriber, the mounting method typically being strand mounted or pedestal mounted. In fiber to the home systems, the drop cable as well as the network side fiber cable typically connect to modules within the module. Even in fiber to the curb systems where coaxial cable is used to connect to the subscriber's premises, the network side module in the node may connect to the network fiber optic cable.
At the node, fiber optic cable or cables are connected to optic fiber connectors within the node. Damage to the fiber optic cable connectors may result from lax cleaning and maintenance practices, or when new additional modules are added or replaced within a node housing when subscribers are added or defective modules are replaced. In a fiber communication system, cleanliness in critically important in providing the best system performance possible. Dust and other contamination at the interface of the fiber cores (fiber core and core of module optical interface) causes performance degradation.
Accordingly, the connector interface must be as free as possible of contamination. As dirty fiber connectors are a common source of light loss at a node's optical module interface, cleaning of node connectors is an important maintenance activity to ensure that the changing and maintenance of a module or modules within a node does not lead to contaminate entry into the node and to migration to the optical connector. In cleaning module connectors, some typical items used include lint-free alcohol pads, alcohol saturated swabs, compressed air directed toward the connector and inspection a magnifying glass to inspect the connector ferrules.
To clean a connector that is inside a module, it is possible to remove the module from the node. However, this is undesirable because of the time cost incurred to disconnect optical and electrical cabling connected to the module and unscrewing the module from the node housing. Thus, it is desirable to have the module remain installed in the node housing. Some attempted solutions have included designing an optical module with a removable cover so that the module can remain installed in the housing while cleaning maintenance can be performed with the cover removed.
While the removable cover may provide access to the connectors, the number of fasteners that secure a cover to the rest of the module be high enough such that the time is consumed by maintenance personnel in removing the cover plate and reinstalling the cover. Not only is the time required high, based on the number of fasteners, but the screws, or similar fasteners, are often small, requiring time-consuming patience by maintenance personnel while removing, and trying to start each fastener into its corresponding hole following maintenance, while the module is still installed hanging from a aerial strand. Thus, there is a need for a module design that allows access to an optical connector enclosed therein for cleaning thereof without the need for either removing the module or removing an entire module side cover.
In addition, when a module is removed or replaced for maintenance purposes, an omega-shaped lifting ring is often inserted into holes in the module top corresponding to each leg of the ring. If the ring is inserted too far into the module, damage, including electrically shorting internal components, may occur. Thus, there is a need for a lifting mechanism that facilitates the lifting of the module from the node housing without potentially causing damage to internal components of the module.
SUMMARY
An objective of the invention is provide a movable window cover to facilitate removal of an optical connector from an optical fiber module. A rectangular window cover having a rectangular notch in a corner intended to be proximate the center of the module slides in a channel and is held the channel by an overhang of a cover that covers the side of the module. Thus, the notch forms two sides of a rectangular opening, the base of the module and the overlap of the side cover forming the other two.
A slot in the window cover allows a screw to pass there through and into corresponding threads on the other side of the cover formed into the base. When the screw is tightened against the window cover, the window cover is secured in place such that the optical connector may be secured to the module by flexible retaining clips affixed to opposing sides of the connector. To prevent withdrawal of the connector from the module, one of the retaining clips bears against one side of a shoulder formed into the base and the other bears against a first side of the window cover along an edge of the notch that is parallel to the shoulder. Ears on the opposing sides of the connector corresponding to the clips limit travel of the connector inward to the module. Such a connector is known in the art and is described herein for purposes of describing the cooperation of the various parts of the invention described more fully elsewhere herein. A removal tab at an end of the window cover opposite the notch may be used by personnel to slide the window cover along a guide channel, and when tightened against the window cover, may be used to remove, or insert, the module into the node housing in which it is used.
Generally described is an optical fiber module comprising a base for locating components internal to the module, the base defining a window and a movable means coupled to the base for covering the window. The movable means defining an opening for receiving an optical connector. The module may define an open side and have a removable means for covering the open side.
The window covering means may be slidably coupled to the base and may further comprise a means for fastening the window covering means to the base in a closed position. The fastening means may include a threaded screw or a spring loaded retaining clip.
The base may include a stop shoulder at a side of the widow proximate the center of the module for engaging, in cooperation with the window covering means, the connector to prevent its movement into the module. The window covering means may also include a removal tab at an end distal to the center of the module when the window cover means in a closed position.
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patent: 6003775 (1999-12-01), Ackley
patent: 6208796 (2001-03-01), Williams Vigliaturo
patent: 6533616 (2003-03-01), Johnsen et al.
patent: 6595423 (2003-07-01), Cho et al.
Eichenlaub, Jr. Frank F.
McLain Dennis
Patel Tulsidas C.
Scientific-Atlanta, Inc.
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