Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-08-24
2003-03-25
Huson, Gregory L. (Department: 3751)
Metal working
Method of mechanical manufacture
Electrical device making
C029S762000, C029S764000, C081S009410, C140S106000, C007S107000, C007S158000
Reexamination Certificate
active
06536103
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to coaxial cable connectors and more particularly to a tool for preparing the end of a coaxial cable for attachment to a male coaxial cable connector.
2. Prior Art
The extended frequency spectrum currently used in cable TV and satellite signal distribution cables, ranging from 5-2000 MHz, together with the present spectrum saturation of airborn signals, have required the industry to increase coaxial cable shielding to reduce radiation of in-cable signals and ingress of unwanted airborn signals. The FCC has created stringent requirements for Cable TV (CATV) connectors, with penalties for Cable TV systems that exceed allowable radiation levels. For this reason, coaxial cable shielding braids have increased from 40% coverage to quad-shielding types consisting of two layers of metallic foil and two layers of 60% braided coverage. Due to economic constraints, the braid materials used for grounded shielding has changed from a mesh comprising soft copper wires to a larger mesh comprised of 0.006-inch rigid aluminum wire.
In the past, when RF shielding was not critical, the coaxial cable connectors, specifically, F-type connectors, only required the braid of the coaxial cable to be cut off prior to insertion into the connector and crimping. The present state-of-the-art connectors are designed to provide a high level of shielding and thus require the shielding braid to be “prepared” prior to insertion into the connector. In order to attach an end of a coaxial cable to a coaxial cable connector, the end of the coaxial cable must first be prepared. During preparation of an end of the coaxial cable, an insulative outer jacket on the cable is first stripped back to expose a layer of braided shielding concentrically overlying a dielectric layer and an electrically conductive central conductor. The end of the cable is also stripped such that the end of the central conductor projects beyond the exposed end of the dielectric layer. The exposed layer of braided shielding is then separated from the underlying dielectric layer, then flared and folded back over the insulating outer jacket adjacent thereto. When the foregoing steps have been completed, the end of the coaxial cable is “prepared”, and is ready to be inserted within the axial bore of a coaxial cable connector for attachment thereto.
When the prepared end of the coaxial cable is advanced into the axial bore of a male coaxial cable connector, a sharp cylindrical shank coaxially disposed within the axial bore intercepts the prepared end and separates the braided shielding and insulating jacket from the dielectric layer of the coaxial cable and becomes interposed therebetween. Advancement of the cable into the connector bore continues in this manner until the exposed central conductor of the cable emerges from the opposing end of the connector's axial bore. In general, the amount of force required to advance the prepared end of a coaxial cable into the connector bore is proportional to the length of the cylindrical shank portion of the connector and the “profile” of an annular barb disposed on the shank. The annular barb is wedge-shaped, and not only forces the braiding and jacket radially outward (i.e., away from the concentrically underlying dielectric layer) when the cable is advanced through the bore, but also serves to anchor the cable to the connector following compression or crimping.
Most of the coaxial cable used for CATV applications has an outer jacket having an outer diameter of less than ⅜ inch. The layer of grounded shielding underlying the jacket is comprised of a plurality of sharp, 0.006 inch diameter strands of aluminum wire, the braid being substantially sturdier than the relatively soft copper wire comprising the mesh braid used on older coaxial cables, which had a soft, fine cloth-like braid that did not puncture the finger. As stated above, in order to prepare the end of the cable for attachment to a connector, the exposed portion of the grounded shielding (braid) must be separated from the underlying dielectric layer and folded back to overlie the adjacent portion of jacket. Lacking a suitable tool, the installer must separate and fold back the grounded shielding with his/her fingers. The cut ends of the wire comprising the grounded shielding of modern coaxial cables are capable of puncturing the skin of the finger. Thus, the cumulative damage to the installer's fingertips, caused by peeling back the grounded shielding on hundreds of cables each day, can be substantial. It would be desirable to have a tool that can separate and fold back the grounded shielding layer of a coaxial cable in preparation for attachment of the cable to a male connector.
SUMMARY
It is a first object of the invention to provide a tool operable for separating and folding back an exposed portion of the grounded shielding layer of a coaxial cable to overlie an adjacent portion of the cable jacket in preparation for attachment of the cable to a male coaxial cable connector.
It is a further object of the invention to provide means enabling a coaxial cable installer to protect his/her fingertips from being accidentally punctured by the cut ends of wires comprising the grounded shielding of a coaxial cable during the preparation of the end of a coaxial cable for attachment to a male coaxial cable connector.
It is a further object of the invention to provide a tool for coaxial cable installation that meets the above stated objectives and is, in addition, portable and inexpensive.
It is yet a further object of the invention to provide a coaxial cable connector installation tool that may be used for flaring and folding the braided shielding on the coaxial cable in preparation for attachment to a coaxial cable connector and which tool further includes means operable for supporting and presenting a male coaxial cable connector for inserting the prepared end of the coaxial cable thereinto for attachment thereto.
The features of the invention believed to be novel are set forth with particularity in the appended claims. However the invention itself, both as to organization and method of operation, together with further objects and advantages thereof may be best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:
REFERENCES:
patent: 3970355 (1976-07-01), Pitschi
patent: 4345375 (1982-08-01), Hayward
patent: 4746305 (1988-05-01), Nomura
patent: 5295864 (1994-03-01), Birch et al.
patent: 5595219 (1997-01-01), Deuel et al.
patent: 6314779 (2001-11-01), Kesinger
Holland Michael
Min-Hua Yeh
Holland Electronics, LLC
Huson Gregory L.
Le Huyen
Petit Michael G.
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