The transferrable EMI gasket assembly utilizes a carrier with a pair of arms, each attached to a back panel by a hinged connection and extending in the same direction to overlie one another. The conductive, deformable gasket material is attached to the carrier and positioned adjacent the back panel. The assembly is collapsed for installation with the back panel overlying one of the arms hinged thereto to present a reduced height. The assembly is placed in the operative position by moving one arm relative to the other to pivot the carrier back panel to a near right angle position with respect to the carrier arms. In the operative position, the gasket material is compressed and deformed against the confronting surfaces to effect the EMI seal while the biasing force of the compressed gasket material, in the preferred embodiment, secures the carrier arms together.

FIELD OF THE INVENTION

This invention relates to gaskets and more particularly to a gasket assembly for suppressing electromagnetic interference (EMI) which may be easily installed and removed.

BACKGROUND OF THE INVENTION

Enclosures or cabinets for electronic equipment are commonly fabricated of metal to provide a supporting enclosure which also forms a continuous grounded conductive surface that affords electromagnetic compatibility (EMC) compliance. It is also occasionally necessary to interrupt the continuous conductive enclosure surface. One example is the mounting of storage devices in electronic equipment which must be accessible from the enclosure exterior for the insertion and removal of storage media such as disk drives or tape drives used in information handling devices. Although the devices mounted at the cabinet opening are enclosed in metal or otherwise conductive housings to preclude EMI problems, spaces can exist between adjoining devices which must be sealed for EMC purposes,

The EMI gasket between adjacent components must provide a continuous seal against both confronting component surfaces and make an adequate contact to ground any charges intercepted by the gasket. In addition, the gasket assembly must be easy to install or remove to accommodate servicing the electronic equipment. Since devices installed at the enclosure cabinet opening may occasionally be removed for service or replacement, the gasket assembly must be capable of easy removal and reinstallation without compromising the gasket function.

A problem often arises wherein the compressive force of the gasket against the confronting surface which is effective to form an adequate seal is greater than the force that is acceptable for assembly and disassembly. Assembly and disassembly must be enabled without compromising optimum design force and required sealing effectiveness.

SUMMARY OF THE INVENTION

The EMI gasket assembly of the present invention includes a carrier attached to a strip of flexible, conductive gasket material. The carrier is formed of a rigid back panel to which upper and lower rigid arms are connected by hinge portions. The carrier may be formed of a single piece of plastic with integral hinge portions connecting the arms to the back panel or may comprise separate parts which are connected by tape or other means to achieve the hinged connection. The hinged carrier enables the gasket assembly to have a collapsed condition for installation and an operative and locked condition with the margins of the gasket material compressed against the confronting surfaces.

The gasket assembly is installed in the opening between two devices with the gasket material laying back, generally parallel with the arm members. In this condition the assembly can easily be inserted into the space between adjoining devices. When inserted to the desired position, the upper arm of the gasket assembly is moved forward and locked beneath a lip formed at the margin of the lower arm securing the upper arm to the lower arm. This process cams the carrier back panel and the gasket secured thereto toward a vertical position which urges the marginal surfaces of the gasket material against the confronting device surfaces with a compressive force sufficient to electrically seal the area between the devices and prevent EMI emissions. The gasket assembly is designed with the relative lengths of the upper and lower arms so related as to allow the upper arm to be moved to a locked position without the back panel reaching a vertical position with respect to the lower arm. Thus, the gasket material is not only compressed against the device surfaces, but also provides the biasing force to retain the upper arm in the locked position in the groove beneath the lip formed on the lower arm. The gasket assembly can then be moved to the final position with the end tabs formed on the carrier lower arm engaging the enclosure frame to limit the distance of penetration of the gasket assembly into the space between the devices.

To remove the gasket assembly from the installed position, a hole in the upper arm is engaged to slide the upper arm back, releasing the edge from the lower arm lip and thereafter moving the upper arm forward to rotate the back panel to the position generally parallel to the lower arm which collapses the carrier, decompresses the gasket material and permits easy removal of the assembly.

DETAILED DESCRIPTION

Referring toFIG. 1, the EMI gasket assembly10includes a carrier12which has a back panel14and a pair of arms, upper arm15and lower arm16that are attached to back panel14by hinged connections18. Carrier12, in a preferred embodiment, is formed as a single part of molded plastic with back panel14and upper and lower arms15and16being substantially rigid and the hinged connections18formed by a reduced thickness, molded hinge or living hinge portions. Alternatively, the back panel and arms could be formed as separate pieces which are connected by tape or other appropriate means to create the hinged connections.

Lower arm16includes an end wall20and a lip21which forms a groove22capable of receiving the marginal edge24of upper arm15when the gasket assembly10is placed in the operative condition. The lip is interrupted at the center and a recess25is formed in the lower arm to facilitate installation and removal of the gasket assembly. The upper arm15has an opening26adjacent the edge27remote from the back panel14and aligned with the lower arm recess25which enables a tool to install the upper arm marginal edge24in the lower arm groove22as the gasket assembly is installed and to remove the upper arm marginal edge from the lower arm groove22to allow the gasket assembly to be collapsed and removed from the installed location. Lower arm end wall20has projecting stop tabs23at each end which project beyond the length of the gasket assembly10which can function to position or limit the distance the gasket assembly is inserted, during installation, as the stop tabs engage cooperating structure presented by the enclosure with which the gasket assembly is used.

The EMI shielding is effected by a flexible strip30of conductive material which is attached to the rear surface of the back panel14along a midportion of major surface32. The flexible strip must provide a continuous conductive surface and also possess sufficient stiffness and elasticity to form an EMI seal with the surfaces against which it is deformed and compressed in the operative position. The elasticity also provides the biasing force to urge upper arm edge24into lower arm groove22and maintain the gasket assembly in the installed position between generally parallel confronting surfaces. The flexible strip30may take many forms from a conductive strip which includes metal particles to a composition of a strip of flexible plastic with a conductive coating. A preferred embodiment used to implement the invention is a strip of foam plastic which has a covering of woven nickel fabric.

Referring toFIGS. 2,3, and4,FIG. 2shows a side elevation of the gasket assembly10ofFIG. 1. Upper arm15and lower arm16extend from back panel14to which they are connected by reduced thickness hinge portions18and the conductive flexible strip30is adhered to back panel14.FIG. 3shows the gasket assembly10collapsed with the back panel14folded back against the lower arm16, reducing the height of the assembly for easy insertion between adjoining components which create the space requiring sealing for EMC. With the gasket assembly10in the collapsed condition ofFIG. 3, the upper arm15extends beyond the lip21at the edge of lower arm16. The gasket assembly10, in the collapsed condition, may be inserted between adjoining components. InFIG. 4, adjoining components34and35are shown with an intervening space that must be sealed to prevent EMI. The gasket assembly10is positioned between components34and35in the collapsed condition ofFIG. 3With the gasket assembly10positioned in the space between adjoining components34and35, which is to be sealed, the upper arm is moved relative to the lower arm to the position whereat the edge24is beyond the lower arm lip and allowed to be captured in the groove22under the lip21as shown inFIG. 4.

The flexible strip30, in the installed position, is deformed or compressed to approximately 60% of the undeformed width or a 40% compression. When compressed or deformed, the flexible strip30has a marginal edge surface38sealed against the lower surface of upper component34and a marginal edge surface37sealed against the upper surface of lower component35to effect the EMI seal to the space between adjoining components34and35.

The flexible strip30also provides the biasing force the retain the upper arm edge24in the captured position in groove22beneath the lip21. To provide a continuous biasing force it is required that the angle A between back panel14and lower arm16be an acute angle approaching a right angle. The length of upper arm15is related to the length of lower arm16to prevent the angle A from exceeding 90 degrees as the gasket assembly is placed in the operative condition by moving the upper arm edge over lip21to a position of capture thereunder.

A second embodiment of the invention is illustrated inFIGS. 5,6and7. Using the carrier12of the preferred embodiment, the gasket material includes compressible strips40and41of foam material covered by a conductive fabric44which also extends between the foam strips and over the back panel14of carrier12to create a continuous conductive surface.FIG. 6, similar toFIG. 3, shows the assembly collapsed to a reduced height for insertion between confronting device surfaces that define a space requiring an EMI seal. In the operative condition ofFIG. 7, the carrier is adjusted to the position wherein the upper arm marginal edge is captured in the groove22beneath lip21. In this operative position, the upper and lower foam strips40and41are respectively compressed against the lower surface46of upper component47and the upper surface48of lower component49.

FIG. 8illustrates a gasket assembly50, similar to that ofFIG. 1, which employs a modified carrier51. Carrier51includes almost identical upper and lower arms53and54, both having a hinge connection to back panel56. The gasket58, formed as a strip of deformable, resilient5material, is adhered to the rear wall surface of back panel56. Each of the arms53and54have a central opening60adjacent the arm edge remote from the back panel56. The gasket assembly50is collapsed for installation (similar toFIG. 3) by extending the upper arm40forward to cause the back panel56to overlie the lower arm41. The assembly is placed in the operating position by moving the upper arm40relative to the lower arm41to align the openings60. To retain the assembly in the operative position, a pin, bolt or other releasable fastener is inserted through the aligned openings60to maintain the relative position of the arms with respect to one another. For purposes of illustration, the releasable fastener is shown as a grooved pin61and clip62, but any fastener structure could be utilized which can easily be connected and disconnected. When the gasket assembly50is used in an environment requiring frequent installation and removal, the carrier arms can be secured by a common twist tie inserted through the openings60and about the adjacent arm edges to secure the arms and removal can be effected by simply cutting the tie. Another releasable fastener for frequent installation and removal of the gasket assembly is the use of aligned hook and loop fastener portions attached to the confronting carrier arm surfaces using a carrier such as that shown inFIG. 8.