Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1999-03-01
2001-02-27
Kincaid, Kristine (Department: 2831)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S034000, C361S816000, C361S752000
Reexamination Certificate
active
06194655
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to shielding devices for minimizing electromagnetic interference and, more particularly, is concerned with an enclosure and an assembly employing the enclosure and opposing covers interfitted with releasable attachment means defined on opposite upper and lower portions of the enclosure which provide for effective shielding of circuit board components against electromagnetic interference.
2. Description of the Prior Art
Electronic components found in various types of transmitters, receivers, computers and other electronic devices emit or are susceptible to electromagnetic radiation. It is therefore desirable to shield circuit components to reduce undesirable electromagnetic interference (EMI) and/or susceptibility effects with the use of conductive shields that reflect or dissipate electromagnetic charges and fields. Such shields are generally grounded to allow electrical charges and fields to be dissipated without disrupting the operation of the electronic components enclosed within the shield.
Various types of shielding devices for electronic components mounted on printed circuit boards have been proposed in the prior art. Representative examples of such shielding devices are those disclosed in U.S. Pat. No. 4,754,101 to Stickney et al., U.S. Pat. No. 4,841,414 to Hibino et al., U.S. Pat. No. 5,014,160 to McCoy, Jr., U.S. Pat. No. 5,043,848 to Rogers et al., U.S. Pat. No. 5,095,177 to Johnson, U.S. Pat. No. 5,160,807 to Fry et al., U.S. Pat. No. 5,175,395 to Moore, U.S. Pat. No. 5,354,951 to Lange, Sr. et al., Japan Pat. No. 62,595 to Tsunoda and German Pat. No. 3,736,833 to Bardon. These shielding devices frequently include a base frame which is mounted to a printed circuit board and surrounds circuit board components and a cover which fits over and connects with the base frame and encloses the printed circuit board components.
Various difficulties may be encountered with respect to providing a satisfactory connection of the cover to the base frame. The connection must secure the cover to the base frame in a reliable manner which prevents dislodgement due to shock and vibration. At the same time, the connection must permit easy removal of the cover for periodic visual inspection of the components enclosed by the shield.
The one shielding assembly disclosed in U.S. Pat. No. 5,354,951 to Lange, Sr. et al., and assigned to the assignee of the present invention, has a connection configuration which has been found to be highly satisfactory in releasably securing a top cover to an enclosure of the shielding assembly. The enclosure of the shielding assembly of this patent includes a plurality of interconnected walls for surrounding an electronic component on a circuit board, a plurality of mounting pins attached to lower portions of the walls for attachment to the circuit board, and a plurality of outer and inner tabs formed in upper portions of the walls for releasably mounting the top cover thereto. The tabs are disposed in a spaced, alternating and offset relationship to one another along the upper portions of the walls so as to create an annular channel between the outer and inner tabs extending along the upper portions of the walls. The top cover has side portions which are removably insertable into the annular channel of the upper portions of the walls of the assembly and into a frictional fitting relation therewith to thereby removably mount the top cover over the enclosure and provide an effective electromagnetic interference shield for the electronic component.
It has been perceived by the inventors herein that a continuing need still exists for improvements in the design of shielding devices for circuit board components that will adapt such devices for use in other applications.
SUMMARY OF THE INVENTION
The present invention provides a circuit board component shielding enclosure and assembly designed to satisfy the aforementioned need. The shielding assembly of the present invention employs an enclosure of the present invention and a pair of top and bottom covers which frictionally interfit with releasable attachment arrangements formed on upper and lower portions of the enclosure so as to accomplish effective EMI shielding of components while allowing the covers to be easily fitted to the enclosure and removed from the enclosure for component accessibility. The upper and lower releasable attachment arrangements preferably are substantially mirror images of one another and thereby secure the top and bottom covers on the enclosure by employing substantially equivalent forces.
Accordingly, the present invention is directed to an EMI shielding enclosure which comprises: (a) a plurality of interconnected walls made of electrically conductive material and being arranged in a polygonal configuration to surround an electronic component on a substrate, each of the walls having an upper portion and a lower portion extending in opposite directions; (b) an upper releasable attachment arrangement formed in the upper portions of the respective walls and adapted for engagement with a top cover when in a first orientation; and (c) a lower releasable attachment arrangement formed in the lower portions of the respective walls and adapted for engagement with a bottom cover when in a second orientation being the inverse of the first orientation of the top cover, the upper and lower releasable attachment arrangements being substantially mirror images of one another.
Further, the upper releasable attachment arrangement includes an upper plurality of outer and inner tabs disposed in spaced, alternating and offset relationship with respect to one another along the upper portions of the walls so as to create an upper annular channel between the upper outer and inner tabs extending along the upper portions of the walls, the upper annular channel being open from above so as to adapt the upper annular channel to receive a downward extending edge of the top cover in the upper annular channel in engagement between the upper outer and inner tabs. The lower releasable attachment arrangement includes a lower plurality of outer and inner tabs disposed in spaced, alternating and offset relationship with respect to one another along the lower portions of the walls so as to create a lower annular channel between the lower outer and inner tabs extending along the lower portions of the walls, the lower annular channel being open from below so as to adapt the lower annular channel to receive an upward extending edge of the bottom cover in the lower annular channel in engagement between the lower outer and inner tabs.
More particularly, each of the walls is substantially planar and has a middle portion between the upper and lower portions. The upper and lower outer tabs in the respective upper and lower portions of each of the walls are integrally connected with the middle portion of the wall and extend substantially in a common plane with the middle portion of the wall. The upper outer tabs have upper ends and the lower outer tabs have lower ends which are flared so as to extend outwardly beyond the common plane of the wall. The upper and lower inner tabs in the respective upper and lower portions of each of the walls are also integrally connected to the middle portion of the wall and disposed in an inwardly offset fashion from the upper and lower outer tabs and extend inwardly and in opposite directions from the middle portion of the wall. The upper inner tabs have upper ends and the lower inner tabs have lower ends which are flared so as to extend inwardly beyond the upper and lower inner tabs.
The present invention is also directed to an EMI shielding assembly which comprises: (a) the above-defined enclosure; and (b) the aforementioned top and bottom covers. The top and bottom covers preferably are substantially identical in configuration to one another. Each of the top and bottom covers is made of electrically conductive material and has a main portion and a plurality of side portions attached to and extending ou
Clements Deborah L.
Lange Louise M.
Lange, II William A.
Lange, Sr. William A.
Flanagan John K.
Flanagan John R.
Flanagan & Flanagan
Kincaid Kristine
Leader Tech, Inc.
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