Magnetic gasket for shielding against electromagnetic radiation

• US 4,820,885 A
• Filed: 09/25/1987
• Issued: 04/11/1989
• Est. Priority Date: 09/25/1987
• Status: Expired due to Term

• Current Assignee: Tom E. Lindsay
• Original Assignee: Tom E. Lindsay
• Inventors: Lindsay, Tom E
• Primary Examiner(s): Grimley, A. T.
• Assistant Examiner(s): TONE, DAVID
• Application Number:
  US07/100,930
• Time in Patent Office: 564 Days
• Field of Search: 174/35 GC, 219/10.55 D, 361/424, 49/478
• US Class Current: 174/353
• CPC Class Codes: H05K 9/0015 Gaskets or seals

Abstract

An electromagnetic interference (EMI) shielding gasket for use with removable and hinged panels of enclosures of electronic equipment, where it is necessary to limit the escape or entrance of electromagnetic radiation through a gap between the panel and enclosure. The gasket includes an elongated metal strip having a clip for easy attachment to the panel or enclosure. The strip carries flexible, electrically conductive sheet material that provides the shield. The sheet material is attached to the strip in a manner to provide a cavity therebetween along their length. A free floating elongated magnet is positioned within the cavity so that it urges the conductive sheet material against an edge of a mating piece of the enclosure by magnetic attraction. The structure conforms to surfaces with significant variations, thereby providing an effective shield, and also assists in maintaining the panel closed against the enclosure.

Claims

1. A structure for shielding against electromagnetic energy penetration around edges of an enclosure opening when covered by a removeable or hinged panel, comprising:

an elongated, electrically conductive, rigid strip adapted to be held adjacent to an edge of the enclosure opening by one of said panel or said enclosure,

flexible, non-magnetic, electrically conductive sheet material carried by said strip along its length in a manner to provide an elongated enclosed space between them, and

an elongated, flexible magnet contained in said enclosed space in a manner to be free floating therein and unattached to either the strip or the sheet material.

2. The structure of claim 1 which further includes means for causing said magnet to have a greater magnetic attraction in a direction away from said strip than in a direction toward said strip.

3. The structure of claim 2 wherein said magnet attraction causing means comprises a non-magnetic insert carried by said strip in said enclosed space between said strip and said magnet.

4. The structure of claim 1 wherein said sheet material is a woven or knitted fabric.

5. A structure for shielding against electromagnetic energy penetration around edges of an enclosure opening when covered by a removeable or hinged panel, comprising:

an elongated, electrically conductive, rigid strip adapted to be held adjacent an edge of the enclosure opening by one of said panel or said enclosure,

a non-magnetic insert attached to said strip,

flexible, non-magnetic, electrically conductive sheet material held between the strip and insert in a manner to provide a cavity that extends along a length of the structure, and

an elongated, flexible magnet contained in said cavity in a manner to be free floating therein and unattached to any of the strip, insert or sheet material,

thereby allowing the magnet to move away from the rigid piece as the other of said panel or an edge adjacent said enclosure opening comes close to said strip.

6. The structure of claim 5 wherein said insert is made of plastic.

7. The structure of claim 5 wherein said sheet material is a woven or knitted fabric.

8. The structure of claim 5 wherein said insert includes a slot opening in a direction away from said strip, said slot having a width slightly larger than that of the magnet, thereby to guide a path of movement of the magnet within said cavity.

9. The structure of claim 8 wherein said slot has a height that is related to a thickness of the magnet and the interior dimensions of said cavity such that movement of the magnet is constrained to remain in said slot.

10. The structure of claim 5 wherein said sheet material is held by frictional compression between sides of said insert and edges of said strip.

11. The structure of claim 5 wherein said strip additionally includes a clip adapted to attach the structure to the enclosure edge, said clip including at least one tine provided to cut through any insulative coating on said enclosure.

12. The structure of claim 5 wherein said insert includes at least one opening extending along its length adjacent said strip, and further wherein said structure comprises at least one cap at an end of said enlongated structure, said cap having at least one stud inserted into said at least one insert opening, whereby an end of the structure is sealed to prevent the free floating magnet from moving longitudinally out of said cavity.