Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1998-07-15
2001-05-01
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
Reexamination Certificate
active
06225555
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to electromagnetic interference (EMI)radio frequency interference (RFI) shielding devices, and more specifically, to a unitary locking EMI/RFI shielding strip.
2. Brief Description of the Related Art
Various types of EMI/RFI shielding devices are known for reducing the transmission of EMI and RFI. Among the known devices are gaskets or strips of a resiliently deformable material which are secured to an openable access panel, door, drawer, or the like (hereinafter “door”), to block the transmission of EMI/RFI through the small clearance between the door and the adjacent structure which forms the opening into and out of which the door is movable. Such strips are useful for shielding openings of housings for electronic components which are highly sensitive to the adverse effects of EMI/RFI.
Such known devices are typically made of one of several materials which have the combined functions of acting as an EMI/RFI shield, and which are resiliently deformable so that they can be compressed between the door when closed, and will spring back to art uncompressed configuration when the door is moved out of the opening.
Prior shielding strips, although providing an adequate level of shielding for the electronic devices, are often difficult to install on an electronics housing and are often not secured to a mounting surface to withstand the forces generated in use without detaching from the surface. For example, one prior strip utilizes a track which is riveted to the mounting surface of the housing, the shielding strip then being slid onto the riveted track to hold the strip in place. Although providing a secure mount for the shielding strip, the riveted track involves a relatively complicated installation procedure, involving several steps, and is therefore labor intensive. Furthermore, a shielding strip which requires a riveted track is relatively expensive, because it requires extra parts (a track and rivets), and added labor to install. The riveted track is also somewhat prone to misinstallation, because installation requires alignment of a rivet with holes in the track.
Another prior shielding strip utilizes an adhesive layer on a portion of the shielding strip which is intended to be mounted on the electronics housing. Although being relatively simple to install, adhesive shielding strips also suffer from particular deficiencies. Specifically, adhesive tends to not be as strong as the riveted track shielding strips, discussed above. If a stronger adhesive is used, the probability of mismounting the adhesive shielding strip increases, requiring destruction of the adhesive shielding strip in order to properly place an adhesive shielding strip on a mounting surface.
Yet another prior shielding strip utilizes one or two long, continuous slots cut into the mounting surface, into which portions of the shielding strip are inserted. If two slots are provided, then the shielding strip is partially expanded, and the entire length of the shielding strip is partially inserted into the slots. The shielding strip is not locked in place, however, and is prone to displacement out of the slots. While providing a good level of shielding when the slots are properly machined, the requirement that precisely machined slots be formed in the mounting surface makes this type of shielding strip more expensive, labor intensive, prone to mismounting, and leads to a heightened potential for EMI/RFI leakage though the slot and past the strip if the slots are machined too wide or long.
There therefore remains a need in the art to provide an inexpensive shielding strip which is easily installed on a mounting surface, which does not require precision machining of the mounting surface, and which locks the shielding strip in place.
SUMMARY OF THE INVENTION
According to a first exemplary embodiment of the invention, a shielding and/or grounding strip comprises a strip of material, the strip including at least one finger extending from the strip generally in a first direction, at least one snap lock extending from the strip generally in a second direction different from the first direction, the snap lock including at least one leg including at least one locking member extending at an angle from the at least one leg, wherein when the at least one leg is positioned in a hole through a mounting surface, the at least one finger is positioned on a first side of the mounting surface and the at least one locking member is positioned on a second side of the mounting surface opposite the first side of the mounting surface.
According to a second exemplary embodiment of the invention, a method of mounting a strip onto a mounting surface which is provided with an opening therein, the strip including a top portion, a finger extending from the top portion in a first direction, and a snap lock including a leg extending in a second direction different from the first direction, comprises the steps of inserting at least a portion of the leg into the hole, deflecting a locking portion of the leg away from an edge of the hole, and pushing the locking portion past the hole such that the locking portion snaps back in a direction toward and past the edge of the hole.
Still other objects, features, and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of embodiments constructed in accordance therewith, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5004866 (1991-04-01), Cooke et al.
patent: 5204496 (1993-04-01), Boulay et al.
patent: 5250751 (1993-10-01), Yamaguchi
patent: 5404276 (1995-04-01), Hansson et al.
patent: 5569877 (1996-10-01), Yumi
Instrument Specialties Catalog, “RF Shielding Selection: A Guide to Interference Control,” CAT-91, 1991.
BrushWellman Engineering Materials Brochure, “Guide to Beryllium Copper,” pp. 4 and 10, Apr. 1992.
Instrument Specialties Catalog, “Engineering Design and Shielding Product Selection Guide,” pp. 62, 64 and 65, Apr. 1998.
Instrument Specialties Catalog, “Product Design and Shielding Selection Guide,” pp. 59-66, Sep. 1994.
Burns Doane Swecker & Mathis L.L.P.
Instrument Specialties Company, Inc.
Ngo Hung V
Reichard Dean A.
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