Electricity: conductors and insulators – Boxes and housings
Reexamination Certificate
2001-01-22
2003-01-07
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Boxes and housings
C174S135000, C174S058000, C385S134000
Reexamination Certificate
active
06504094
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of equipment enclosures and more particularly, to an apparatus for mounting such equipment enclosures and for protecting cables which are connected to equipment housed therein. By way of example, the invention may be applied to the mounting of telecommunications equipment having fiber optic cables connected thereto.
BACKGROUND OF THE INVENTION
Electronic equipment conventionally comprises an enclosure such as a box-shaped housing containing electronic circuitry. In some instances, the front of such a housing is open so as to provide access to shelves, each of which may be configured with receiving stations for holding electronic circuitry units in a side-by-side relationship. Housings of this nature are prevalent in telecommunications equipment applications. When installed into such housings, one or more of these electronic circuitry units may be connected to a communications network using fiber optic cable. The fiber optic cable carries communication signals to and from the electronic equipment. Typically, each front vertical edge of the housing has a mounting flange that is generally perpendicular to the sides of the housing. The mounting flanges may be used to attach the equipment to a support structure therefor, such as vertical rack, as is well-known to those versed in this art. The rack has two parallel, vertical members which are spaced apart by a distance slightly greater than the width of the housing and each vertical member is typically secured to the floor. The vertical members each provide a mounting surface to which the mounting flanges of the equipment housing may be removably attached. In compliance with the Electronic Industries Association (“EIA”) standards, set out in EIA document ANSI/EIA-310-D1992, rack members are typically spaced to correspond to standard housing widths. Standard widths used for housing are typically 19 inches, 23 inches, and 30 inches. (These standards are similar to those of the European Telecommunications Standards Institute (“ETSI”), as disclosed in ETSI document ETS 300 119-2.) Several racks may be lined up side by side and organized into parallel rows known in this art as equipment line-ups. Each row is separated from the other by a predetermined distance which provides access to the front and back of the electronic equipment so that the equipment may be serviced.
Alternatively, the mounting flanges may be secured to an adapter which is attached in turn to the vertical rack. The latter mounting arrangement is known to those skilled in the art as mid-mounting, and the adapter in question is termed a mid-mount adapter. Generally, the mid-mount adapter provides a web which is generally oriented perpendicular to the mounting flanges of the equipment housing. The mid-mount adapter thereby allows for the equipment in question to be mounted to the rack such that the front face or front surfaces of the equipment housing are spaced apart from the front surface of the rack. Thus, the vertically disposed mounting flanges of the equipment housing will be horizontally offset from the corresponding mounting surfaces therefor which are found on the rack.
Mid-mount adapters are employed for the rack mounting of electronic equipment in order to conform with ETA standards. Newton Instrument Company of Butner, N.C. manufactures a typical standards-compliant adapter (Newton part numbers 21386401 to 21386408) for mounting the housing to the rack. The Newton adapter comprises a planar metal web that is five inches wide, with parallel, symmetrical flanges traversing the longitudinal edges of the web. The cross-section of the adapter is generally U-shaped with the flanges being perpendicular to the plane of the web. The flanges are provided with a plurality of screw holes therethrough. The screw holes correspond to screw holes located in the mounting surface of each vertical member of the rack and in the mounting flanges of the equipment housing. Screws are inserted through the holes in the flanges of the adapter into the corresponding screw holes provided in the rack and in the flanges of the housing. The rack is thus located at or about the mid-section of each side of the housing. This mid-mounting arrangement provides service personnel with access to both the front and rear of the housing when the housing is arranged in equipment line-ups. A disadvantage of this arrangement is that the flange along the front vertical edge of the housing or that of the mid-mount adapter itself protrudes and may at times accidentally catch on equipment or clothing of repair personnel. It has also been known for repair personnel to collide with these protruding edges of the housing or adapter in certain prior art mid-mount adapters.
In a typical installation, the fiber optic cable protrudes from the front of the housing at or near its point of connection with the electronic circuitry unit. The protruding cable hangs vertically over a portion of the front surface of the housing. In a lower portion of the housing, the cable is partially wrapped around a protrusion in the front surface of the housing, as is known to those in this art. The protrusion has a curved surface which the cable follows, causing the cable to be drawn horizontally across the front surface of the housing. At the point at which the cable reaches a vertical edge of the housing, the cable is partially wrapped around the mounting flange and is run either up the side of the housing into a ceiling or down the side of the housing into a sub-floor cable raceway system.
When certain of the known mid-mount adapters are deployed in the foregoing installations, the cables will typically be exposed to potential damage or mechanical disruption at the sides and front of the equipment housing. Moreover, these unprotected cables may hang loosely from the front of the housing. In this arrangement the cable is often caught on the clothing and equipment of maintenance personnel when they service the electronic equipment contained within the housing. When the cable catches, it may also disconnect, which may lead to increased maintenance costs. If slack in the cable is reduced, problems may also arise because the cable must then be wrapped tightly around the mounting flange of the equipment housing or adapter flange. This causes the cable to bend unduly, often forming a bend radius of less than one inch. If the fiber optic cable is bent with a radius of less than one inch then a Bellcore industry standard for bend radius pertaining to fiber optic cable is not satisfied. This standard, set out in Bellcore Generic Requirements document GR-78-Core, at paragraph R5-34[170], states that “[s]ingle optical fiber cables shall not be bent to a radius of less than one inch at any stage during manufacturing or field deployment.” A bend radius of less than one inch in the cable may cause fiber fracture which causes a loss of the signal being carried by the cable. If fiber fracture occurs, the cable must be replaced. Users of the communication signal carried by the damaged cable also may lose revenue for the time that they are unable to use the fiber optic cable.
In other known installations, the cable is guided alongside the equipment housing by an extruded plastic three-sided conduit, or cable management system, with a rectangular cross-section. The conduit's opposing sides are formed by a plurality of narrow resilient fingers. The remaining side is comprised of a continuous web. The resilient fingers protrude in the same direction from the longitudinal edges of the web and are perpendicular to the web. The conduit is vertically attached to the rack and the cable is wrapped between two or more narrow fingers to hold it in place as it traverses the conduit into either the ceiling or sub-floor, as previously described. The cable system may alternatively be configured to have a second three-sided conduit. In this alternative configuration, a second set of resilient fingers protrude perpendicularly from the longitudinal edges of the web but
Bundza Nicholas A.
Cecire Yoan
Woo Raymond
Alcatel Canada Inc.
Blake Cassels & Graydon LLP
Estrada Angel R.
Reichard Dean A.
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